Why Gravity is NOT a Force

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The General Theory of Relativity tells us gravity is not a force, gravitational fields don't exist. Objects tend to move on straight paths through curved spacetime. Thanks to Caséta by Lutron for sponsoring this video. Find out more at: www.lutron.com/veritasium

Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his JPvid channel: ve42.co/gfl or his books: ve42.co/GFLbooks

Amazing VFX, compositing, and editing by Jonny Hyman
2D animations by Ivàn Tello
Filmed by Steven Warren and Raquel Nuno
Special thanks to Petr Lebedev for reviews and script consultation
Music by Jonny Hyman and from Epidemic Sound epidemicsound.com

Rocket made by Goodnight and Co.
Screen images in rocket by Geoff Barrett

Slow motion rocket exhaust footage from Joe Barnard at BPS.Space









コメント数 46 773
Veritasium 年 前
Here's a question I've seen a lot in comments: OK, I'm accelerating up but then shouldn't someone on the other side of the globe fall off? No, here's why: Either watch again from 8:28 or read what I've written below... Spacetime is curved - it curves the opposite direction on the other side of the Earth. Neither us on this side of the Earth nor they on the other side are changing our spacial coordinates - we're not moving up, they're not moving down - Earth isn't flying into one of us. BUT we both ARE accelerating. In curved spacetime you have to accelerate just to remain stationary. The traditional definition of acceleration is something changing its velocity. In general relativity you have to embrace a new definition of acceleration: it means deviating from a geodesic - not going on a straight line path through spacetime. Near the Earth a geodesic is a parabola so unless you're moving in a parabolic arc (like on a zero-g plane) you are accelerating. This definition is the same as the old one so if you're accelerating in deep space then your velocity is changing. *BUT*... if you are near a large mass you are in curved spacetime, now acceleration your velocity is changing. You can stay stationary relative to Earth's surface and still be accelerating. This is because your acceleration should be measured not relative to the Earth's surface but relative to free-falling objects - they are inertial observers. Imagine this - I'm in deep space and I make horizontal rows and rows of stationary golf balls. Then I hop in my rocket and accelerate up through them. Just think about what that looks like. Now my rocket is back on Earth just sitting there. I freeze time for a sec and make horizontal rows and rows of golf balls up into the atmosphere. Now unfreeze time. What do you see? If you just look at the golf balls and the rocket ship it looks the same as the situation in space where the golf balls were stationary and the rocket was accelerating. Einstein's point was the golf balls have the better claim as the "stationary" thing since their experience is just like the golf balls in deep space - no forces experienced. The rocket on Earth is just like the rocket in space. It feels a force and hence an acceleration.
Ju Don
Ju Don 8 ヶ月 前
But doesn't the fact that there's no such thing as stationary in our universe since everything in it is accelerating dispel that theory? I mean since absolutely everything and everyone is accelerating through space with the expansion of the universe what makes the free falling person or the person out in space's experience of being stationary more valid than mine?
Aditya Pereira
Aditya Pereira 9 ヶ月 前
I cant explain what I understood or how much I related to the information you shared.. It is however a spiritual experience when u find someone thinking alike for a rookie..
Keldren Raze
Keldren Raze 10 ヶ月 前
@Steve Wright honestly it doesn't exist.. it's just observing, measuring and predicting change. He only mentioned moving through time as a helix of motion to simulate the earth also orbiting the sun even as an object orbits the earth.. so adding the concept of "moving through time" would change the shape of the movement 3 dimensionally, it has no further significance in this instance.
The Action Lab
This video is a masterpiece. The best explanation of gravity on the internet currently.
Shriniwas Bhoite
Shriniwas Bhoite 18 日 前
Fiorintino Cogin
Fiorintino Cogin ヶ月 前
The lack thereof
1000 Subscribers CHALLENGE With NO Videos!
Case I --> An observer falling, see the person standing on ground accelerating upwards. Case II --> An observer standing on ground, see the person falling, accelerating downwards. Therefore, Observations are different when we see from different perspective. So, how can you tell which perspective is the correct one. We find the Newtonian physics true because we are standing on Earth. But as we expand in space, we should change our perspective
Ângelo Zanatta
Ângelo Zanatta 7 ヶ月 前
Explanation of what? 😂
Mingash-منقاش 7 ヶ月 前
The two great scientists meet. ⚡️🤝🔥
Diego Solis
Diego Solis ヶ月 前
What I find the most amazing about Newtonian physics, is that Newton was able to come up with so many simplifications for phenomena that are incredibly complex and plainly "crazy". That man made science possible for so many minds which then lead us into a world in which we have a deeper understanding of the universe and still his simplifications work beautifully in most cases. He came with approximations that measure the effect of the complexity, rather than the complexity itself. Ain't physics and math a couple of beautiful things? Sure they are!
Dorian Anreiter
Dorian Anreiter 8 日 前
Sir Isaac and I went to the same school. His name is still carved on a window surround in the library. he may have been a genius but he still graffiti-ed things!
Jim Mcneal
Jim Mcneal 28 日 前
And his first, second and third laws still hold true till this day
Diego Solis
Diego Solis ヶ月 前
@Dominik Patola Something like that. I've read somewhere that he saw it from his window and that made him question "why everything falls to the ground everywhere, even if the earth is round" So that's why he figured there had to be something always pulling you towards earth's center. And through his amazing mathematical skills he ended up coming up with his famous equations.
Dominik Patola
Dominik Patola ヶ月 前
@Diego Solis I think it fell on the ground instead of his head
Super.Chuck ヶ月 前
@Diego Solis His marketing manager probably said " Hey Newton, this is a bunch of mumbo jumbo, if we can hatch a STORY to tell everyone, the masses will PAY you to publish and repeat this STORY and they dont need to understand the underlying math.
UrogHai ヶ月 前
It's not that gravity doesn't exist, it's that it's a property of masses & spacetime. And we can treat it as a force for most purposes without causing issues.
Matthew 4 日 前
Could he not have simply said, “Gravity is not a force because it has no mass, which violates Newton’s second law, F=ma.” Yet, photons are affected by… I need to rewatch the video.
M K 5 日 前
@Dean Kyle This is the same as the other guy trying to tell us that electricity does not flow in wires or it's not a movement of electrons... But hey wanna believe it, go for it... If gravity does not exist then we'll need to re-write physics and whatever we were taught is totally wrong... Believe what thou wilt..
Dean Kyle
Dean Kyle 5 日 前
@M K did you not watch the video at all? That's like the first thing he covered in it. Actually watch the video and try to understand what he's saying before you comment
M K 5 日 前
@Dean Kyle OK so you jump from a 5 storey building and then tell me gravity does not exist when you reach the ground. Provided you're still alive, that is..
Dean Kyle
Dean Kyle 5 日 前
@M K not just that gravity isn't a force, gravity simply doesn't exist, so no need to rewrite the definitolion for something if the thing you are reqriting it for doesn't exist
Melody ヶ月 前
Every time someone points out that the stretchy fabric demo i always am mindblown that we just accepted without issue a explanation for gravity that requires gravity to work
Stephen Scharf
Stephen Scharf 14 日 前
There is no *fabric* to "spacetime". There is _nothing_ there.....and, with all due respect to Veritasium, gravity mediates it's effect through a field. Just as a magnet does (and there are no "virtual photons" mediating a magnetic field, either).
MobileRDS 27 日 前
Veritasium, thank you! I find not your presentation, but the fact being right on the spot. Also, making your presentations more accessible to public (not to mention for those not highly math addicted!), you're doing wonderful job of spreading the word of science!
Ananya Ravikumar
On a lighter note, this means that the apple didn’t fall on Newton’s head. He accelerated right into it.
Antonio Fumagalli
That's wrong: he actually was sitting under a pear
virupaksha walla
virupaksha walla ヶ月 前
They are all models reflecting the way our brains work. I like the infinite turtle one better.
virupaksha walla
virupaksha walla ヶ月 前
Apply could sue.
Super.Chuck ヶ月 前
​@THE LORD REY IO like the phrasing you used in some of the observations. But, and this is a BUT, Mass, has no weight WITHOUT Gravity. That is why everything falls at the same rate in a Vacuum. It's also why every object IN space (the space junk floating around we junked up ) stays in the same spot all the time. It's indispuatable there is a Gravatational Force. Something is defeinately happening. So they have used a bunch of poorly defined terms to try and make sense of it, I agree. But it's enough to get started discussing it. Look up the map of earth's gravity, it is not the same the world over, there are high and low spots. Your quote "DENSITY of MASS is what determines how much an object WEIGHS" No. The reason everything falls at the same rate..... is because Density of Mass has no meaning FOR Gravity. Total weight at it's basic element is only has a defined weight WITHIN Gravity, because of Gravity. An object of Lead (High Density), 3 feathers tied together and a quart of vanilla ice cream all FALL at the same speed. (in a vacuum so Air doesnt come into play) They only have WEIGHT because of Gravatational Force acting upon them. (It's cumbersome to write Gravatational Force all day so it's shortened to a simple term, Gravity)
Kamaboko Gonpachiro
uk y other peeps didnt come out like newton? cuz they sat under coconut trees.
Pradeep Thomas
Pradeep Thomas 19 日 前
A year after rewatching this multiple times I should say this is really the best explanation out there on gravity. Thank you for making this video and explaining this concept. Relativity had always been beyond the reach of understanding for me, until now.
Jamie Hitt
Jamie Hitt ヶ月 前
It’s like being taught that it’s a flashlight… But then finding out that it truly is a darksucker.
Eugene Bunt
Eugene Bunt 2 日 前
Einstein explained gravity over one hundred years ago: He said it was warped space-time and told where to look for it, the bending of light in a gravitational field. He explained the bending of light was caused by space rising from the surface of the Sun, as space rises light coming from the background constellation passing close to the surface of the Sun, enters the rising space at a higher level on the far side, and as the space rises it exits lower on our side as it travels toward us making, the images of the stars appear as if they are at a wider angle away from the Sun (the gravitation lens effect). He also said time slows in the presence of mass, with rising space coming from the core of the Earth (our gravity source) we move farther, faster toward the gravity source than matter moves away from it. With matter moving toward the core, matter applies pressure on the core, anything put under pressure radiates heat (long-wave energy) in essence elongating the fabric of space vertically to the planet's surface which allows light to make longer jumps per second. Change in momentum lags behind the change in velocity. Matter does not pull on matter, we are decelerating on the planet's surface at the rate of acceleration that the core is expanding new space as the surface pressure is heating the core. Gravity is a change in uniform motion.
Kevin J
Kevin J ヶ月 前
Interesting that we've been unable to test the radiation of particles. I'd be interested in seeing a video on why the particles of Earth itself couldn't be tested. Aren't they accelerating and thus radiating? And if so, any device that measures 0 for their radiation would actually be measuring their radiation with bias, thus subsequently that same device put into space would become an inertial observer, and it would then measure all other particles also in that frame of reference as a negative radiation?
Wave 年 前
"Gravity is an illusion" flat earthers: "WRITE THAT DOWN WRITE THAT DOWN"
hiren Drall
hiren Drall 4 ヶ月 前
@Alex Wilson lol
Blidea 7 ヶ月 前
The fact that flat earthers' theory about the acceleration force moving us """"""up"""""" is actually right confuses me.
NYCFenrir 8 ヶ月 前
@Wave A flat earther legit reference this video to me and said gravity doesn't exist because it's apparent. Also said the earth is flat because the rocket is flat in the video.
dorkle 9 ヶ月 前
@Science Revolution ok what the hell I'm trying to get this comment out but yt keeps deleting it. I've been trying for an hour now
Science Revolution
Science Revolution 9 ヶ月 前
@dorkle station. Station.
stephentoons 2 ヶ月 前
Finally a good explanation. I never liked the balls on a rubber sheet analogy for gravity because it depends on gravity to work and so seemed circular. no pun intended.
John Walsom
John Walsom ヶ月 前
I never liked the explanation of gravity with gravity either, but was not yet aware of the space time thing. I told myself the "well" was in a fourth dimension of space....Time? Heck! Could space just be another spatial dimension i wonder?
Ben Zöchling
Ben Zöchling ヶ月 前
Just to test if I understood this correctly: Does that mean that Spacecrafts do a "Flyby" around a moon or planet, because that is actually the straightest line from one point to another through bend space?
George Youtube
George Youtube 22 日 前
It wants to travel in a straight line but gets deviated by gravity with a change in velocity. If that was the straight line trough bent space there would be conservation of momentum, no change in velocity, just change direction. The velocity change suggests it clearly does not follow a straight path
steveshadforth 26 日 前
No, they do it because the force of gravity exerted on them causes a deviation in the actual flight path.
Sourabh Tondale
Sourabh Tondale ヶ月 前
acceleration is the force.
Earthling-Z3R0 ヶ月 前
No. It's just a measure of gaining acceleration.
Aibak Agbariya
Aibak Agbariya 29 日 前
A good simulation would be Imagining the space time fabric as a pool of water , I am not a physicist but accelerating heavy round object inside a pool should bend the liquid in a relative radius to the object weight and speed(space time fabric ) ,which will cause geodesics in the pool (deviation of space time fabric) ,now by dropping a light weight object into our geodesics , we should have our heavy object pulling the other object closer to it until it hits it and turn into stationary state (synchronized speed ,with the light weight object sticking to the other) Please one more video of this topic like to get attention
Aniirudh Singh
Aniirudh Singh 10 日 前
Awesome Reperesentation....as always. I had a tiny query, which seems to have not been covered in the above video is that: If gravity as stated by you, is an Illusion, then why do we have low and high tides, which are cause by the combined gravitational forces of the moon. Please shed some light on that!
PicSci 7 日 前
True, explain
Morpheus 年 前
When mountain climbing, try not to become an inertial observer.
Yash Sahu
Yash Sahu 17 日 前
Wtf bro. I know I'll be laughing on this joke at random nights for years. XDXDXXD
Mohammad Reza
Mohammad Reza 28 日 前
swells plays
swells plays 29 日 前
ut user is almost morbius
Freackedman ヶ月 前
@sergeant recker the way you said it makes me feel threatened by 1631 people including you
nobody important
nobody important 16 日 前
In high school i always imagined the random kinetic energy in an object to be dragging it in every direction equally. Just a thousand vector lines popping off an object like the spines of a sea urchin. But if you smoosh a couple of those directions together, suddenly a lot of those directions are working together to overpower the rest. It just made more sense to me than energy from nowhere
wes333 ヶ月 前
The easiest way for me to imagine gravity, is to think of anything with mass as a drain that swallows space at the speed of gravity. The more mass you have squeezed together the stronger the effect. The closer you get to the drain the stronger the effect. If there is infinite space you can't suck it all down the drain. Or there may be a finite amount which would make me think there is something out there doing the opposite and emitting space. These things would behave in a way that they couldn't be close to anything they would be getting further away from everything all the time. So I imagine them being spread evenly more or less all through the universe. If that's the case everything else in the universe would also unless normal matter eats the stuff. If there is a balance between space eating normal matter and this other stuff, everything would be stable.
Grimmshred Sanguinus
isnt a black hole workin like this
Anish Jog
Anish Jog 4 日 前
1:57 The man in the rocket ship wouldn't detected Gravitational waves (assuming that there is no mass outside his spaceship perfect infinite vaccum) while the one failing of a roof would do. Could this be the experiment by which one can distinguish the two situations?
Freddy M.
Freddy M. 2 ヶ月 前
Incredible (well not anymore of course) my proffesor did a similiar transition from Newtonian physics to relativity yesterday. Rewatching this compared to when it first came out, I can really appreciate much more the topics addressed.
Wehrewulf X
Wehrewulf X ヶ月 前
Mike Tacos
Mike Tacos 11 ヶ月 前
At this point, Newton throws his apple at Einstein.
John Steed
John Steed 7 ヶ月 前
@Feynman Schwinger E_MC2 Thanks for your comments.
Guy The Incognito
Guy The Incognito 7 ヶ月 前
@Feynman Schwinger E_MC2 Thanks. You're welcome 😎👍
Feynman Schwinger E_MC2
@Guy The Incognito This is a fantastic summary 👏👏👏. Great job. (I just hope he/she understands what you wrote, they seem to have an axe to grind).
Feynman Schwinger E_MC2
@Guy The Incognito Fun fact, Einstein discovered most of the truly original concepts in quantum mechanics too: quantized the radiation field, specific heat of solids, wave-particle duality 13 years before De Broglie, intrinsic randomness with his trilogy of papers on Spontaneous and Stimulated Emission as codified in the Einstein A and B Coefficients, he, not Bose, discovered the Boson, he was the first to point out quantum entanglement and flesh out the reason why this was central to quantum mechanics deviation from classical mechanics even while the likes of Bohr, Heisenberg, Schrodinger etc failed to see it. I could go on and on. He's the most original scientific thinker of all time imo, and I'm not sure it's even close. In an era replete with generational geniuses, they considered him chief amongst them - which is why they insisted he sit in the very middle of the portraits they would shoot for the Solvay Conferences. The same way Einstein was inspired by Newton, Faraday and Maxwell, Heisenberg was inspired to become a physicist because of Einstein. He adored Newton, I suspect, because they were both after the same thing: they wanted to know the mind of God. Thanks for you commentary. Great stuff!
fluentpiffle ヶ月 前
"Gravity is caused by the mass-energy density of space. This mass-energy density of space is determined by the square of the Wave-Amplitude and is always positive (squares are always positive). The wave-velocity is inversely proportional to the mass-energy density of space, the higher the mass-energy density of space, the slower the Wave-Velocity. As Matter and its resultant mass-energy density of space are always positive, this causes a slowing of In-Waves as they travel through other matter/wave-motions, and it is this property of Space that causes the natural ‘Gravitational’ attraction of all bodies, and explains why Gravity is always attractive." (Geoff Haselhurst) "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion
Hugo 27 日 前
I've just watched your other great video on the speed of light and whether this is a constant speed in both / all directions. Can you please explain to me why the experiment mentioned in this video at circa 13:00 couldn't be used to determine if light was moving faster in one direction to another? I.e, by shining the light through the accelerating rocket ship from 2 opposite directions and seeing if the difference in where the light is measured inside the ship is equal (or not) on both sides. Excuse the wordy question but I have no science background, hope I've made sense.
Beyond Batcoif
Beyond Batcoif 19 日 前
If C is different in different directions, one wall of the ship is not where you observe it to be, because you are observing the different speed light from the opposing direction light. The experiment would show the same both directions for different reasons.
Neutronplant 25 日 前
The difference would simply be too small to notice or measure.
Justin B
Justin B 2 ヶ月 前
I'm still confused, when you said we are accelerating up on earth, first thing I thought was the earth would have to expand for that to be accurate, which you quickly called out. Love how you present this, and know what people will think. Will watch again.
Swedish Racing League - Mogg Fantastic
@Zudabaker Orbiting IS free fall. There is no difference. Satelites are in free fall towards the earth and just have enough sideways speed to miss all the time. Same with everything in orbit.
N Marbletoe
N Marbletoe ヶ月 前
@wtfduud yup, if the earth stopped moving in time it could be traveling at c relative to us, so it would disappear
wtfduud ヶ月 前
@M If the Earth stopped moving through time, it would disappear for us (if we continue moving through time without it).
M ヶ月 前
@Zudabaker So if theoretically Earth stopped moving (all types of movements), then the gravity would stop existing around it?
Zudabaker 2 ヶ月 前
Essentially because it is a mass in motion. So, since the earth rotates, and travels around the sun, and is a large mass, we're all constantly moving even when we are staying still. Up as in out, as in outwards from the earths crust. Since the earth is not only a large mass, and it is in motion, it bends space time relative to it's momentum. At least that's what I think is being suggested. Essentially, if the earth didn't have this momentum, it would either drift further away from the sun, and us along with it, or closer into the sun, and us along with it. But because of it's orbit, it constantly has perfect momentum. The sun builds incredible amounts of momentum, because it too is in orbit around the center of the galaxy. Making each planet, similar to a satilite, in flux between free fall, and and escape velocity. That is the force we are experiencing. Momentum. And we're just along for the ride. Same reason why sometimes stuff sticks to your windshield even though your driving fast but can whipe it off as soon as you get out of the car. We're essentially close enough to that distorted time space that we're along for the ride. Similar to being in a space ship. Only a space ship doesn't have that amount of mass and doesn't generate enough momentum to have people traveling on the outside of it, but bits of dust yes. On the inside, you experience the momentum, just like you don't experience the momentum of being inside a car unless you're accelerating, but if you get hit by one. Oh boy. Making each time you jump, an attempt to break from that momentum that earth has to distort space time in the way it does. What would be interesting to see, if it is momentum itself that is at work or that and other things. Like, if earth was not moving, at all. Would something still change it's course and run into it? And at what rate? How much does space time bend for mass alone? Or would something running into it give it momentum, even the smallest amount, and that would cause it to warp space time?
Martin Eizinger
Martin Eizinger 26 日 前
THANK YOU for critiquing the bent sheet experiment. I've always hated when people used this to demonstrate gravity.
pankaj mishra
pankaj mishra 24 日 前
over simplification and plain wrong analogy. a similar one has been used in elementary science books to explain uncertainty principle.
As long as I've known Derek he's consistently asked the difficult questions. This video challenged me, and taught me many things. I want to try the eclipse photo now. Impressed Eddington did it in 1919.
Steve Jones
Steve Jones 2 ヶ月 前
Eclipse is about 2 years away.. Still planning on doing this?! Make a video on your planning - I know there's a lot of us who would follow along and maybe try to do the experiment at the same time. Last eclipse, we went to Kentucky to watch.. Next time we're planning on going somewhere between Texas and Illinois.. DEFINITELY can't miss it!!
hiren Drall
hiren Drall 4 ヶ月 前
I still did not understand why we dont fall on the other side of the earth
Starlight 7 ヶ月 前
@Laith Ejeilat the word you're looking for is physicist, a physician is totally different from one who works on physics
RandomThings 10 ヶ月 前
In 1919, Whipple declared that comets were dirty snowballs. When they actualloy sent spacecraft to comets they found very little ice but lots of rock, rubble, plains, sand dunes and cliff faces. So they called them icy dirt balls. Hahahahahahahaha.
pedro de la calzada
Thank you Veritasium for helping to disable the very much confusing, though always used, example of the mass ball on a rubber sheet to visualize the space time curvature. Much better and intuitive is the model developed by Rickard Jonsson from Chalmers University by rolling the time on a circular polar coordinate. And even building a wooden model for illustration purposes !!!!. Must check it !!!!
5kom5 ヶ月 前
This is by far, the best explanation of gravity I have ever listened to. It’s so refreshing to hear a truth you didn’t know before.
Randy Martin
Randy Martin 4 日 前
Mind blown, the way that you explained the formula, and explained the interaction between acceleration and spacetime, how science fiction had the idea so long ago that if superman flew around the planet in reverse, he could go back in time
Paul Gutches
Paul Gutches ヶ月 前
If one could "fall forever" from that roof, would one suffer the same kinds of physical deterioration involving bone mass loss and red blood cell destruction seen in astronauts who experience weightlessness for extended periods?
Thraxus 26 日 前
@Paul Gutches Because all other factors are identical to what Astronaughts experience. Weightlessness is the only thing that Astronaughts experience regularly that regular humans on Earth do not
Dave Koch
Dave Koch 29 日 前
Yes, because it would be absolutely no different than an astronaut experiencing weightlessness. They are literally the same thing.
Dave Koch
Dave Koch 29 日 前
@Kuhluh Ok - just trying to get it straight in my mind. As I understand it, my explanation would be in line with general relativity.
Kuhluh ヶ月 前
@Dave Koch well, my explanation is for the classic way of thinking about it yours is for the one of the video
Dave Koch
Dave Koch ヶ月 前
@Kuhluh Is this true? Isn't orbit just an object travelling in a straight line through space time? Since the earth is bending space time that straight line is basically a circle (more of a spiral when you factor in time) around the earth?
Veritasium: *"gravity is just an illusion"* Flat Earthers: Our Time Has Come.
Nowhy 3 ヶ月 前
@mmldmm proof in science? Interesting...
mmldmm 3 ヶ月 前
if gravity is just an illusion why are they still looking for proof of the graviton?
Richard Singer
Richard Singer 4 ヶ月 前
@LewisPhillips name one of these multiple PhD holders and I will show you someone who bought multiple fake PhDs.
Sakis Sakissa
Sakis Sakissa 5 ヶ月 前
This guy is a liar "gravity does not exist" omg 🤣👏👏👏👏
R. Mayer
R. Mayer 2 ヶ月 前
Really good graphics, really good comparative explanation. Keep up the good work.
Tim Hill
Tim Hill 2 ヶ月 前
Thanks for this video. I had a discussion and disagreement with some people over the nature of gravitation. I called it an acceleration, while all the others in the discussion insisted it was a force. I sort of backed down, explaining that in the Navy, we always did our math by considering gravity to be an acceleration, and I pointed out that the units are the same whether it's a force or an acceleration. This quieted most of the disagreements down. But now I wish I could have shown them this video. But now I wonder why I just didn't tell them that Einstein redefined gravity to be just what I had affirmed, an acceleration. That would have redirected the discussion quite well.
N Marbletoe
N Marbletoe ヶ月 前
@Jordan Sure, I'm not saying what gravity "is." If you want to figure out what it DOES to a shell, you could use gravity as an acceleration = 9.8 m/ss. That will tell you the gravitational input to the trajectory. Or, you could use gravity as a force = Gm1m2/d^2 and then plug the answer into f=m1a, and get the same answer for a, 9.8 m/ss at sea level. This is all Newtonian as long as the Navy isn't using relativistic bombardment.
Jordan ヶ月 前
@N Marbletoe What you are describing does not make gravitation an acceleration. You are still treating it as a classical force by subjecting it to Newton's first law. It just so happens that since mass of the object is time invariant (for the purposes of most simple calculations) you can remove it from the momentum and gravitation sides of the equation. Will you get the correct answer in most large scale cases? Sure, but you are fundamentally misunderstanding what you are doing by cancelling the mass.
N Marbletoe
N Marbletoe ヶ月 前
@Jordan good point, the units are different, but the results are the same. in other words one can solve for the position of a shell over time by considering gravity as a force or an acceleration. different formulae, same result, since the mass cancels out when you apply f=ma ... to get the accel
Jordan ヶ月 前
Acceleration units : m/s^2, Force Units : Newtons (kg * m/s^2). Want to explain to me how those units are the same?
N Marbletoe
N Marbletoe 2 ヶ月 前
it causes things to move, therefore it's a force. but, you don't feel it unless other forces act against it, in which case you only feel the other forces, so it's not a force.
Dave Sulphate
Dave Sulphate ヶ月 前
While the video was great, please remember to say that things fall at the same rate "in a vacuum". Less educated people will find feathers, parachutes and helium/hydrogen balloons rather enigmatic. Seriously, a great video but the fact that most educators forget this really irritates me for some reason.
עולם הגיקים
Dude, you are amazing! I haven't watched a single video on this channel that didn't leave me completly shocked almost like Christopher Nolan does.
*Matthew Noneya*
*Matthew Noneya* 11 ヶ月 前
Mom: "son did you fall down?" Son: "No mom, you fell up!"
grindupBaker ヶ月 前
Mom: "son did you fall down?" Son: "No mom, the dratted Universe just fell up on me again !"
J Tyson
J Tyson ヶ月 前
Son: "No, I went into my inertial frame"
save earth
save earth 6 ヶ月 前
@Bunsenn that's what i said in the first place
Bunsenn 6 ヶ月 前
@save earth You didn’t fall down, you fell towards the center of the earth.
daniel howard
daniel howard 10 ヶ月 前
I am standing here looking down I see my feet and the ground. The ground is deff down. And happens to also be exactly where I was when I stopped falling. Unless I am upside down. I dont care what way I fell it freaking hurt
K F 20 日 前
Thanks for this video! One of your more accessible ones for sure. Just one caution--your spacesuit and helmet didn't fit together to seal you in. f you go for a space walk, this could be dangerous.
Wossen Getachew
Wossen Getachew 2 ヶ月 前
I have watched this video like 5times this may b his best work. Much respect for Derek 👍🏼
hansi's corner
hansi's corner ヶ月 前
I always saw our perception of gravity as an effect. Cool that a gut feeling is right.
shawkat hasan
shawkat hasan 3 日 前
Hi Derek, one quick question. To simulate gravity on a rocket, the rocket must be accelerated by some external force. However on earth there is no force working to create the pull of gravity because gravity is not a force, it’s just curvature of space time. In one scenario external force is present in the other scenario no external force involved. Can we conclude these 2 scenarios are identical ? Thanks
Narf Whals
Narf Whals 2 日 前
On earths surface there is a force on you. The international pressure of earth keeps the surface at a constant radius and it, in turn, pushes on you.
Props for the camera man who went through space to film this video
IMC00KIES 2 ヶ月 前
@The onion from Shrek he's just a kid calm down
LeWoucheBait 年 前
@JC_Boy What do you mean yeah yeah?
JC_Boy 年 前
@LeWoucheBait yeah yeah ". "
LeWoucheBait 年 前
@JC_Boy Yes I can, what are you talking about?
Ali ヶ月 前
I feel like the main reason we misinterpret gravity as a force is cause unconsciously we mistake it with the normal force of surface so many times
Valerie Pallaoro
Valerie Pallaoro ヶ月 前
It's called 'reification'. Where we take an explanation for a concept, and end up thinking it's real. I sometimes think that's why he exists, to get us out of this muddle.
Andrew Bennett
Andrew Bennett ヶ月 前
Omg, thank you! I've been saying this crap for many years and gotten a lot of negative feedback. After all, who am I, a nobody, to say gravity doesn't exist? Actually had one guy call me an idiot when I tried to explain that objects fall at the same rate. I even started to wonder if it was just pride convincing myself I was right about what was really just an assumption. Thanks for vindicating me!
David Mitchell
David Mitchell ヶ月 前
Just to be nit-picky, as someone who has sky dived, you don't feel weightless. You feel like you're slamming into air like when you stick your hand out a car window. The falling elevator example is better.
Eu29 Lex
Eu29 Lex ヶ月 前
You feel gravity when you skydive, what mushrooms are you on ? Lol. If you didn't feel gravity you would not see yourself falling. Also, I'll see how much you think gravity is not a force when you jump without a parachute and let it's power slam you into the earth.
Usopper ヶ月 前
Only due to air resistance, or else it is exactly as described. Falling elevator intuitively feels better because there is minimal air resistance, but both are one and the same.
Jeff Little
Jeff Little ヶ月 前
@Shiven [IITB] I think his point is that the air under you when you skydive is a weaker version of the floor pushing up on you when you are standing.
Shiven [IITB]
Shiven [IITB] ヶ月 前
I'm pretty sure that you don't experience a force due to gravity while sky diving, rather a drag due to air resistance that has nothing to do with gravity, so both examples are perfectly valid here.
Sam Ancor
Sam Ancor 15 日 前
The way to tell if space time curves or not around objects is to view the orientation of the rocket. When your space man is on his straight line through space time and curving towards the planet. Somebody observing the situation should see a visible rotation or change in orientation of the rocket pointing toward the planet as it gets closer. If gravity is a force however his orientation should remain the same when he is pulled into the planet causing him to crash into the planet side ways.
Nixon 4 日 前
That’s interesting, and I think, correct
Nolan Bie
Nolan Bie 年 前
The fact that you can make videos on topics that are so out of the ordinary, and most people would never be able understand it without years of education, into a short video that is free to watch and actually understandable is amazing
Max Odgaard
Max Odgaard 年 前
@Sky King not even the most famous astrophysicists can explain from where gravity origins, so I am amazed you understand it. Be humble and admit you dont either :)
Rishu Mallick
I based on the people watching,if they are interested then they will do what they need to do to understand the video but if they are here just because they just want some of their brain cells to die then they will leave. U am just 14 i will turn 15 in july,i am studying in my last year of junior high, i was completely able to understand the whole video but i am intrested in robotics. All i have left to say now is "everything is knowledge and we should take it". Thanks for reading,have a nice day👍🏻
Dushyant M
Dushyant M 年 前
You don't need years of education to get the basics of relativity. I read 'ABC of Relativity' by Bertrand Russell. Very beginner friendly book, very interesting and got me a good grasp of the basic concepts.
Bruh Broham
Bruh Broham 年 前
@Max Odgaard actually, this is my mom's account B)
Max Odgaard
Max Odgaard 年 前
@Bruh Broham stop using daddys youtube account.... and go do your homework..... yalla yalla
Paul Barker
Paul Barker 2 ヶ月 前
I always thought of gravity as the same kind of thing as magnetism. Magnetism acting on ferrous metals, and gravity acting on all mass. Is this not so? How are the two different, other than level of strength? Although magnetism doesn't act only on ferrous metals, does it? Otherwise electricity wouldn't be caused to flow in a copper or aluminum wire moving through a magnetic field, but it is. Probably electric current is caused to flow in any material moving through a magnetic field, in proportion to it's resistance, availability of valence electrons, etc. Just as we can now use magnetism to produce electric current, and use electric current to produce magnetism, I figure we will eventually figure out how to produce gravity.
N Marbletoe
N Marbletoe ヶ月 前
gravity acts on a line between the objects, while magnetism acts at 90 angle
Nick Isquick
Nick Isquick ヶ月 前
@veritasium So what I understood is in general relativity, any object that experiences force is accelerating because it is deviating from its geodasics. And objects always follow straight line path in space time and they are not experiencing any forces and they are in a state of weightlessness. From their inertial reference, everything is accelerating past them. So, when a person is falling down to earth is accelerating but from their inertial frame of reference it would look like everything else is accelerating past them. My question is how is gravity an illusion, is it because it is objects with mass stopping other objects from following a straight line path? And what is an example of deviation from geodasics. My bus of thought ends here.
Eu29 Lex
Eu29 Lex ヶ月 前
" strength or energy exerted or brought to bear : cause of motion or change"- Since gravity keeps things in motions and pushes them towards the other is still looks like it acts how a force is described. People saying "gravity is not a force" is the result of overthinking and not understanding what "force" means, which is no surprise there. Also, gravity is a motion towards the earth generated by mass, that's what a force is.
AL 2 ヶ月 前
Curved spacetime is caused by planets (or any object in space) displacing the fabric of space and causing this fabric to now be abundant and "squeezed" around said object. (We know space is a fabric because of gravitational waves. The waves have to travel throughsomething) Like a bowling ball thrown in a pool. The ball takes up the space the water once took up. The difference of an object in space is space is in a vacuum, and space is constantly expanding, expanding everywhere. Now that the fabric of space is in multiples around our planet (curved spacetime), multiples of a negative pressure that is constantly expanding, a sort of hole is created in space. If another object comes into contact with our planet's curved spacetime, it will now travel towards our planet. Multiples of a negative pressure in space is like having less wind resistance on earth. When an object is traveling through space it'll travel on the path with less resistance. Multiple negative pressures is less resistance than a negative pressure. Multiples of a negative pressure is also what stretches out so far across space, and is what causes objects to "attract" each other. Matter doesn't attract matter. It's the existence of matter that causes matter to attract. Take Oumuamua for example. It traveled an unimaginable distance from the sun. If "objects attract" why didn't Oumuamua collide head on with the sun? As for gravity on Earth, or any object in space, the constant expansion of the universe is what causes it. The experiment on the moon, dropping a hammer and feather at the same time, showed us that. The reason they travel at the same speed is because the universe is expanding at a steady speed. The more dense an object the more the object displaces the fabric of space. The more displacement if the fabric of space the stronger the gravity. Also, magnets attract because of the expansion of space. This expansion cant travel through dense objects. It travels around very dense objects. When dipoles are aligned in an object it causes what we call magnetism. Density = high magnetic permeability. BTW, the "tic tac" object (ufo on military video) is traveling outside of the expansion of space. It has found a way to be so dense that the fabric of space pass through it. The craft isn't affected by gravity or inertia. It is outside of space, similar to a black hole. That's why the tic tac video show the object as being blurry around it. That is curved spacetime. I just watched a video called "boiling water at room temperature". They simply put water in a sealed container and pulled a vacuum on the container. And the water boiled. Another word for boil is traveled. Because of the negative pressure the water, what water is made of, was able to travel throughout the container. Similar to what we see in space.
AL ヶ月 前
@N’Diaye Ball I was high when I wrote it. I don't even remember writing it;) Just kidding, I'll get with you later today. Busy day currently...
SongLuigi 2 ヶ月 前
I want to strongly contradict the following sentence "The waves have to travel throughsomething". That was a common misconception for light as well!
Inverted_Realities 2 ヶ月 前
Ok, so what curves space, and stops time with a black hole, where there is no massive objects in space to displace space time ? The gravitational force perhaps ?
N’Diaye Ball
N’Diaye Ball 2 ヶ月 前
What you're saying here is awfully interesting, you got me hooked on the first 3 paragraphs. But then i started getting lost after the fourth paragraph, maybe i think it's because i had trouble understanding the "multiples of a negative pressure". Would you mind explaining it in a another way maybe ? I'd really love to have a grip on what you're saying here. Thank youuu
Raj Datta
Raj Datta 年 前
But the question is, why does space time curve around massive objects?
Valentino Nathan
Valentino Nathan 23 日 前
maybe matter is "anti-spacetime" ?
sìN 29 日 前
@Ch Tη thanks for the golden explanation man
Arihant ヶ月 前
Bro i really think asking "why" Is not a thing it is "how" We should think about
Robin P Clarke
Robin P Clarke ヶ月 前
@Zalidia They have "the greatest genius in history" on their side so QED as far as they are concerned. "Spacetime" is arguably another concoction like "dark matter" and "dark energy".
Mohan Bhojaraja
Mohan Bhojaraja ヶ月 前
Why is there something instead of nothing?
Matt Morris
Matt Morris 25 日 前
Man I come back to this video every couple months and I understand a little bit more and realize I don't understand a little bit more
Godchi1d Von Steuben
Gravity (here on Earth) is a combination of electron exchange between the Earth and objects on it, combined with the weight of the atmosphere on said objects. Weight generated by the same electron exchange occuring with the elements that make up our atmosphere. Suns, black holes, these things have tremendous mass. More mass, more atoms, more atoms, more electrons, more electrons exchanging with atoms surrounding said sun, or black hole. This exchange both draws elements in towards the sun, and allows larger clumps of elements headed towards the sun, to grab smaller clumps of elements, allowing planets to form. These objects are in rotation around the sun. The rotation is caused by the release, and return of ions from the sun. Ions escaping collide with ions returning, forcing them to move out of eachothers way. The direction they most commonly move out of the way creates a twist in the ionic convection, lending rotation to the sun, or black holes, gravitational pull. Now these clumps being pulled towards the sun, begin rotating, rather than being pulled straight in. You are in constant motion, your spatial coordinates are constantly changing, as the planet you are standing on is in rotation around the Sun. This prevents you from traveling a straight line through time space, as you are fixed something that is traveling in a circular motion. How are you fixed to it? By the same force drawing elemental matter towards the center of the sun, just as you are being drawn towards the center of the Earth, just all smaller bunches of matter drifting in space, are drawn towards the center of larger bunches of matter, allowing planets to form. If there were no gravity you would not get crushed at the bottom of the ocean. It's the fact that water is denser than atmosphere, ergo has more matter to exchange electrons with the Earth, generating more gravitational pull against the water, than against atmosphere, leading to your being crushed under the oceans weight, while maintaining your normal size/density on Earths surface. Thus explaining how mass and inertial mass can be identicalal, though the force to resist tham may vary.
Jake Mustian
Jake Mustian 18 日 前
The two situations feel different because of air resistance. You feel the acceleration of gravity because the felt wind is getting faster
Apollo Jetic
Apollo Jetic 2 ヶ月 前
Learn something new from every video I view. Amazing content! Thank you!!
Colton Smith
Colton Smith 年 前
So Newton actually rammed his head into that apple. Rude.
18MCE1024 Siddhant Kaskar
😂😂😂😂😂😂😂😂 legends
James Kenyon
James Kenyon 9 ヶ月 前
@Memerr Thanks, somebody clued me in awhile back and so I'm good. Bottom line is professor Dave couldn't debunk his way out of a wet paper bag.
Memerr 9 ヶ月 前
@James Kenyon lol But you don't use + to mention someone you use @
Artem D
Artem D 9 ヶ月 前
Earth is to blame here!
Huskie Huskerson
Huskie Huskerson 9 ヶ月 前
To apple? Are you insane?
Chris Foster
Chris Foster ヶ月 前
I have another question... If I were to be able to alter spacetime around me (maybe to lose or gain the "illusion" of gravity), would that same power allow me to alter time itself? Even reverse it or fastforward it? I mean not just to a nearby observer... I mean to the whole universe?
Maxime Bret
Maxime Bret 27 日 前
If you could alter spacetime around you, you would be able to make things move faster the more you bend around it. Let's say you decide to bend space time at a specific point (on a human for example), you would make this human age faster than you. For this specific person, it would look as everything around is going slower. (that would be a hell of an experience for that person by the way). This is why astronauts on space station age slower than you (and satellite have automatic clock adjustment). For them you are the one in a more bended space time. So yeah to answer your question, you could theoretically fast forward time around you. your power would be something like being able to concentrate a massive mass somewhere. However you cannot reverse time. That is currently impossible based on current knowledges. Disclaimer, I may not be 100% right with everything I said.
United States of America
13:40-13:50 Really puts into perspective how strong black holes are for them to be able to send light back in the direction it came. If your body were to go into a small one's event horizon (and be completely invulnerable somehow), it'd probably feel like being hit by truck weighing around 88,690,000,000,000,000,000,000,000,000 average American trucks combined, near light speed.
United States of America
Also, sorry if I got the number of trucks wrong. Ironically, I'm not good at math, despite loving physics. lol
Micah McWilliams
Micah McWilliams ヶ月 前
In addition to feeling "weightless" the observer would also have have visual cues, such as the stars shifting as he turned toward the planet. Unless the observer is "crashing" into a singularity, light would better reference for inertia than feeling weightless.
Swedish Racing League - Mogg Fantastic
Visual cues can't distinguish between you changing path or every one else changing path.
Vikramjit Singh
Vikramjit Singh ヶ月 前
I always had confusion on this topic before but this video is kind of a masterpiece. Salute Veritasium ...........
Shamsun Islam
Shamsun Islam 11 ヶ月 前
my physics teacher: Draw an arrow showing the direction of gravity. me: [draws nothing] my physics teacher: What video did you see this time?
Richard Moore
Richard Moore 6 ヶ月 前
@James Sutton You are missing the point. Locally the environments are equivalent. Any experiment you do on a sufficiently small scale will produce the same result in each inertial frame. If you expand the volume included in the experiment, then and only then will you see differences (tides and orbital mechanics are examples -- these are non-local phenomena).
brb 6 ヶ月 前
@Frank Krumnow so wrong what you say
This Guy
This Guy 8 ヶ月 前
@Yori Senpai gravity 100% exists lol what do you mean
Nguyen Nguyen Huy
Nguyen Nguyen Huy 9 ヶ月 前
@James Sutton Actually, the analogy doesn't say falling and acceleration looks the same and therefore they are the same. It says that they have the same effect that is certain and stops there, thought of an experiment in acceleration and derive it into a one in gravity, which is affected by the same effect as I said, and then came up with a conclusion. This kind of comparing apples and oranges is valid. You can say that apples and oranges are all trees or dogs or whatever, and all trees and all dogs have supplies of water or have abc ... , therefore there must be a lot of water in apples, and so do oranges or some other conclusion from things in effect of abc.
FishermanChannel 9 ヶ月 前
You should draw arrow down. While gravity has no force, it still curves spacetime and arrow represents general direction of curvature in given location.
Michelle Fitzpatrick
I truly hope you read this comment in its entirety as I am highly curious about this and have taken a special interest in these concepts recently. I have so many query’s lately and this video although fascinating and informative has only brought up more questions. If you have any tips on books or resources I can explore and absorb I would be eternally grateful! Currently deciding if I want to go back to college for physics/theoretical likely yet I’m old and completely new to these concepts. Sorry for the novella! By your explanation of force both the positive stationary charge and the falling negative charge would give off electricity, no? The positive because it inertia matches that of the earth or possibly it’s slower which is why it stays attached to the object it’s sitting on and the negative or falling ball because it inertia is present only that it is moving at a different rate from that of the earth until it touches the ground when it’s inertia matches that of the other ball and other objects with perceived gravitational pull attached to the earths surface. What I find confusing is how our measured weight is the same regardless of where we are on the earth’s surface. I suppose this could be explained away by a higher dimension in which we can not actually perceive the true shape of the earth or it’s surroundings in outer space but I don’t have enough knowledge yet on these topics so I could just be lacking in understanding. Curious however if you have an explanation for any of this. As far as the earth expanding which honestly makes the most sense in layman’s terms wouldn’t that mean that everything else in space is also expanding at the same rate as earth? If everything in space is moving in an ever expanding manor wouldn’t this be a legitimate explanation? On another note why do we not use the ocean for more research into these concepts? Water has to bend around objects moving through it in addition at the correct depth and mass of an object, things feel weightless or their inertia matches that of the water surrounding them, right? That being said unless a round object is expanding in all directions simultaneously, another object on its surface would have different effects depending upon the part of the surface it’s touching. For example, Some things fall off the back and others are stuck. This would be the same or similar in space as under water, would it not? Water from a faucet can bend as do bullets shot in a long range, airplanes etc… interesting and yet to date none of these theories seem to truly explain well enough for us to fully understand or completely prove/disprove. Knowledge should be ever changing and expanding yet we have been so specifically focused on the already presented concepts that to date no one has expressed any valid, in-depth and provable newness. I suppose there could be some unseen variable/s no one has yet considered. If everything in our lives and perceptions has variable why wouldn’t space/time also. Isn’t time just a perception anyway. A way we as humans explain the way we experience life and history… my mind is spinning 😵‍💫 Slightly off topic but what is the possibility that the golden ratio has the ability to aid us in the understanding of some or all of these concepts? To much to explain this question but I have faith that your level of education and higher thinking can put the pieces together for this inquiry. Thank you for sharing your knowledge and helping to keep me curious and passionate about learning! I truly appreciate you and your work! Off to continue my understanding of these concepts…
Michelle Fitzpatrick
@D-man cat good point about buoyancy force! Suppose I didn’t take that into account. Like I said I’m completely new to these concepts and essentially learning from a laymen’s perspective. 🤣 still highly intrigued and apprentice of your comment.
D-man cat
D-man cat 6 日 前
by his explination i dont think the falling one would give off anything. Im not 100% what you mean but depending on where on earth you are a scale would show slightly different numbers because the earth is not a perfect sphere nor is it uniformly dense. He explained why the earth isnt expending at 9:57 though i guess if everything is expending it wouldnt be noticable. Water also applys a force onto you called the buoyant force so its not the same as being weightless. If you ever try diving you can feel the water pushing you up.
Lee Trampleasure
Lee Trampleasure ヶ月 前
Doesn't the model of gravity as a force still 'work' for most dynamics/kinematics/energy experiments/problems in a physics class (or even discussion)? If we define a force as an interaction between two objects, than isn't the bending of space/time simply a definition of HOW these two object interact, but it's still an interaction.
Patrick Powers
Patrick Powers ヶ月 前
The simple comment on this is that if gravity was a force then every time we dropped anything or gravity affected things then the energy used would slow down the earth's rotation on its axis and in its orbit. That we do not see. Therefore gravity is not a force.
fluentpiffle ヶ月 前
The problem is that the nature of 'gravity' is linked to the nature of how existence itself operates, so there will always be a 'problem' until our understanding correlates with the actual nature of reality.. Fortunately, we live in times where this understanding is a possibility.. "Gravity is caused by the mass-energy density of space. This mass-energy density of space is determined by the square of the Wave-Amplitude and is always positive (squares are always positive). The wave-velocity is inversely proportional to the mass-energy density of space, the higher the mass-energy density of space, the slower the Wave-Velocity. As Matter and its resultant mass-energy density of space are always positive, this causes a slowing of In-Waves as they travel through other matter/wave-motions, and it is this property of Space that causes the natural ‘Gravitational’ attraction of all bodies, and explains why Gravity is always attractive." (Geoff Haselhurst) spaceandmotion "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science."
Kuhluh ヶ月 前
well, we ALWAYS simplify stuff engineers also don't go and calculate how every single particle of a machine interact with each other (even though it would maybe be more accurate) another example: we know a few million decimal places of Pi, but even the Jet Propulsion Laboratory uses less than 50, if I remember correctly
14:58 Can anyone explain "And General Relativity has passed *virtually every* test put to it..." Which tests were not passed? (And why do we keep using the word "gravity"?) "near a large mass you are in curved spacetime," How does time curve?
Pradyut Fogla
Pradyut Fogla ヶ月 前
Here spacetime is not a term defining "time in space" Just like colgate isn't a "gate".
Duncan Chouinard
Duncan Chouinard ヶ月 前
Genuinely I can't understand this in school, I'm a little older than highschool, but I feel like I can take a test after watching your videos and legit look like one of the smartest people. You're so easy to understand and I love the models. You may not believe in visual learning, but they never did that in school for me sooooo. Seeing the exaggerated beam of light when the rocket moves up, legit made me understand what you were saying.
Aahil Wani
Aahil Wani ヶ月 前
Everybody gangsta until school asks numericals
Aaron M. Lambert, Ph.D.
*As a Harvard Neuroscientist, here's another mind-bending gravity-related thought. When you rotate your head, you are NOT in control of the primary directionality of your eye movements under most circumstances.* Try this. Keep your head still and look at your finger while you shake your finger left and right; your finger will look blurry due to motion blur. Now, instead, keep your finger still and look at it while you simultaneously shake your head left and right, which will demonstrate - in this situation - that you are still able to maintain a stable image of your finger. This is because your gravitationally-influenced sense of your head in space - your vestibular system - has a hardwired reflex to move your eyes in the opposite direction of your rotational head movements. This vestibular-ocular reflex (VOR) ensures automatic dynamic stabilization of images during head movements. You are not consciously doing this, and you can not consciously override it. The VOR is truly a reflex and, interestingly, does not depend on vision. During head movements, you will still have a strong VOR if you are in the dark or if you have your eyes closed. Your VOR originates from your vestibular system, which is located in your inner ear right next to your cochlea - your organ of hearing. Your vestibular system for rotational head movements consists of a series of three fluid-filled semicircular canals that have little "hair" cells inside the canals. When your head moves up-down (pitch), left-right (yaw), or shoulder-to-shoulder (roll), fluid inside the corresponding semicircular canal flows. This head motion-induced flow bends the hair cells within the canal to ultimately send electrical impulses to your hindbrain. These electrical impulses - encoding head movement - then talk to parts of your brain controlling eye movements, which connect to your eye muscles to reflexively move your eyes in the opposite direction of your head movement. So be thankful that your sense of your head in space - your vestibular system - takes care of maintaining a stable image of the world even when your head bobs around as you walk. Otherwise, walking would be a blurry journey of craziness. Videos coming soon.
W0LF 21 日 前
CykeOk 年 前
So to sum it up... we humans have evolved a Steadicam in our heads, because if we hadn't, things would blur every time we move...? Nice.
Dmitriy 年 前
Yep, this is exactly why I hate motion blur in games. Cause usually they(devs) make it that everything is getting blurry with every move you take so even walking gives you motion sickness. And of course there is no focus on anything it just all blurs. Which normal people only experience when dead drunk.
Throefly 年 前
Nice. This explains handily why cameras with no image stabilization(either digital or optical) result in such shaky looking video, and by extension also why watching movies that substitute camera shake in for various special effects can be so frustrating to watch.
nunya biz
nunya biz 年 前
Mind blown
Killer Opus
Killer Opus ヶ月 前
I think Buoyancy already describes what the word GRAVITY tries to describe. Everything is trying to find balance in its available space and will stretch out or compact depending on the objects involved. Water fills it container as well as air. Density/Weight also plays a role in buoyancy just as you would say gravity is causing. The medium in which something is in, on or under will determine where the object ends up through buoyancy of the two objects or multiple objects are within. Heat/Cold - Temperature also finds balance. Temperature also changes the buoyancy of an object or medium.
Killer Opus
Killer Opus ヶ月 前
@Griffyn Productions XD
Griffyn Productions
Bro, are you a flat earther or something? This doesn't make a lick of sense.
Shadow CSM
Shadow CSM ヶ月 前
Derek, with the stretched sheet experiment, if there was no force being exerted on the object travelling along the geodesic line, what role does acceleration play? For instance, and I realise you said not to think of a "well", but if the object doesn't maintain sufficient countering force (via its engines), its orbit around the planet will decay and it will eventually crash into the planet (hence my simple understanding of the object sliding down the wall of the well). To break from the gravitational attraction of the planet (ie, to maintain its straightline path through space time along the geodesic), or to curve away from the planet, it has to exert a force greater than the gravitational attraction (ie, to climb the wall of the well). Or am I completely off? (This is what happens when you think year 12 physics and pure and applied mathematics is enough to answer all your questions on the nature of all things ...)
Seth N.
Seth N. ヶ月 前
correct...going into those "curved sheet areas" around planets that represent space time dips and taking advantage of their ability to accelerate things is how we slingshot spacecraft in the solar system. If you skim the edge you will accelerate and yet not get caught in it
account old
account old ヶ月 前
Oh yeah, the Sagnac effect - used specifically on ring laser gyroscopes. Acceleration of the gyroscope induces a small phase shift on the laser, which is detected by an interferometer.
ssisnake ヶ月 前
I love the amount of time it takes for previous beliefs to be adjusted and corrected over time, it doesn't help that some of my highschool books were from 15-25 years before I entered highschool and I'm sure there are many places like that outdated information spread as true with no ill intent but wrong nonetheless.
Benjamin Tollison
Officer I can't walk in a straight line because we all walk in geodesics.
X Zero One Armour
X Zero One Armour 5 ヶ月 前
You get Promoted, Private
Leonardo Krügel
Leonardo Krügel 10 ヶ月 前
And then proceds to walk in a straight line through space-time
sts 11 ヶ月 前
@Brett Goldsmith Geodesics aren't straight lines to flat-earthers.
slicedpage ヶ月 前
sometimes the most complex conundrums are really just common sense. Thank you
Abhishek Verma
Abhishek Verma 13 日 前
As you explained in an accelerating frame light would deflect, would light still deflect for an observer floating in space far from any gravitational effect. Would a man in space (again far from gravitational effect), still be able to see light bending or deflecting from a very very far away heavenly object like blackhole cause if he is free falling then he is in an inertial frame???
Victor Contreras
Victor Contreras ヶ月 前
Really interesting as Physics always is. Seems that we are learning more about all this as time goes on. I used to hear about the "force of gravity" and now I understand that it is not a force! It makes sense to me⚠️
Toms Bondars
Toms Bondars ヶ月 前
​@fred flintstone It didn't. Did you watch the video?
Mario Paul
Mario Paul ヶ月 前
@fred flintstone you completely missed the point of the video, Mr. Flintstone.
fred flintstone
fred flintstone ヶ月 前
if it isnt a force why did the planet pull the rocket towards it. gravity is a force, strange as it seems but it is, and we can measure it to.
Ron Disanto
Ron Disanto ヶ月 前
You are an amazing person for making this video. Thank you
Sciencerely 年 前
As a stem cell researcher I've recently read about studies investigating why organisms need gravity to develop and would have great difficulties in spaceships. Early attempts of growing plants in spaceships failed since plants need gravity for their root development. However, even single cells need gravity for molecular processes. For example, the cytoskeleton (which help cells to maintain their shapes) and several protein families have been shown to be affected by the absence of gravity (it would actually be funny to make a video about that myself). Great video as always!
BD 10 ヶ月 前
It's mathematically proven that a large circular object to contain living quarters on a space ship can generate artificial gravity by simply spinning the object, like a spinning donut.
TechyBen 年 前
@AlbertaGeek Better semantics from me would be: The acceleration of particles and molecules in a cell use their accelerating non-rest reverence frame to push off the straight path resistance in a gravity well of curved spacetime. ;) There, no "force" in that example, but the cell is still using gravity to actually function.
TechyBen 年 前
@AlbertaGeek Oh I totally understand the video. If I bounce some balls on a trampoline, these are not a "force". You can however use those balls to likewise bounce some dice off them. As you say, it's semantics. So "gravity" provides something we can push off of, in the same way acceleration provides something to push against.
Gov Corp Watch
@AlbertaGeek so, you don't grasp how the conceptualization of physics is different, you just compare to the standard model and that's it. really?
AlbertaGeek 年 前
@Gov Corp Watch _"did you even read the energy wave website?"_ Yes, I did. That's why I said what I did.
bmbdr529 ヶ月 前
I'm still having trouble understanding how spaceships' slingshot maneuvers work when they pass close to planets. There should be no noticeable acceleration for the space traveler. Are they just taking a shortcut through space-time? Why are they faster after leaving the planet relative to the earth afterwards or are they not at all?
Ulaş Aldağ
Ulaş Aldağ 3 日 前
The maneuver of a ship around a planet only changes the trajectory of the velocity relative to the planet, without changing the actual value. Relative to the planet it slingshots around, it has still the same velocity just in another direction, so it actually doesn't accelerate. The magic happens when you look at it relative to the sun after the maneuver. The changed component of the velocity is now partly parallel to the velocity around the sun and therefore increaes the total velocity relative to the sun. Of course this scenario only works for acceleration, you could also use it for a braking maneuver by turning the velocity in the opposite direction.
John Walsom
John Walsom ヶ月 前
Exactly! I can never understand why you don't lose on the way out what you gained on the way in. Maybe it is just being used for the change of direction ie no net gain in velocity, just staying on the right track.
TacticusPrime ヶ月 前
The planets are also moving relative to the sun and to the Earth. The spacecraft gets close behind the planets, using the traveling warp of spacetime as a sort of tug to increase their own speed relative to the sun and the Earth. Like Marty McFly on his skateboard behind a truck.
Caspians Friend
Caspians Friend ヶ月 前
I was drawn in by the "Grand Day Out" like rocket (and excellent choice, IMO) but stayed for the mind bending explanation of spacetime! wow!
cocoweepah ヶ月 前
The secret of “gravitivity” is revealed by gyroscopes. And I hope rocket man has a 3-axis-compensating gyro on board instead of just rocket fins in the vacuum of space. Fins on the side of a rocket’s tube will only provide stable “guidance” in a gaseous atmosphere. They are useless in a space-vacuum. Even the inside movement-contacts of an astro-nut would send the rocket into wobbling, disorienting pitching, rolling and yawing from its original smooth, ‘linear’ trajectory within a gaseous atmosphere. I sorta learned the first childhood lessons of “the necessity of fins on amateur-rocket tubes” launched in the air (atmosphere). If misaligned the rocket tube will spin. If the fins are ripped off or missing the launched rocket tube will move in an unpredictable or ‘exciting’ (often dangerous) erratic, chaotic trajectory.
Patrick Houchins
Patrick Houchins ヶ月 前
Well it's a secondary force made from the combination of primary forces, speed + mass = gravity (+space density/energy but we don't include that now)
spacejunky 10 ヶ月 前
Trying to explain this to a friend is a crazy challenge. I've tried. I think it's more confusing, this is such a great explanation
Average Alien
Average Alien 7 ヶ月 前
@Jay D All that means is that it's an incomplete model that can't explain everything. The things it does explain, it explains perfectly well. Just like newtonian gravity explained many phenomena perfectly. But when it came to things like the orbit of Mercury, it couldn't account for that. Same goes for GR. It can't explain the rotation speeds of galaxies, or the singularity of a black hole.
Jay D
Jay D 7 ヶ月 前
@Average Alien however it cannot explain gravity at the quantum level, so you can’t completely accept the legitimacy of it
Juan Carlos Buenaventura
@CyberWolf Vsauce "Which way is down?" is a GREAT video. 👍 Veritasium, Vsauce and Kurtzgesagt (with all their differences) are examples of great quality and engaging educational content, made by motivated and talented people outside the traditional TV and editorial industries.
spacejunky 8 ヶ月 前
@Medicus yep which is why I rewatch the video
Medicus 8 ヶ月 前
If you can't explain it You didn't understand good enough Albert Einstein
jean claude bertoni
To quote a Physics teacher I had many years ago. "There is no such thing as gravity. The earth sucks!"
Tziona Minkin
Tziona Minkin 2 ヶ月 前
I legit got a headache but I think I understand the general theory of relativity now, thank Ve!
Kumod Singh
Kumod Singh 2 ヶ月 前
Actually the concepts of these videos were very fundamental even I knewed it but I enjoyed a lot in this video by learning some more fundamental concepts. Iam a 11th standard student and I love physics.
Pedro Norman
Pedro Norman ヶ月 前
I've never heard gravity described like this and the philosophical implications are tremendous.
So newton wasn’t observing the apple, the apple was observing him
ojas pk
ojas pk 11 ヶ月 前
Samir Mokadem
Samir Mokadem 11 ヶ月 前
​@hydrolito So, was there a reason at all why you though that your input would have any sort of value? I mean, since you apparently didn't bother to see the video these comments are in regards to before replying.
hydrolito 11 ヶ月 前
@Ehab Taha Apple exists how else would I eat them?
hydrolito 11 ヶ月 前
@Samir Mokadem I seriously doubt Issac Newton accelerated up, more logical the apple fell and hit him.
Silience 年 前
@jesse robinson Just because you don't understand it, does it mean that it is wrong. Personal incredulity... here's not smashing random words. All of this is proven, it has been proven by countless experiments. It's hard to understand I know, I've tried understanding it for years and im barely grasping the basics, it's not easy to accept that reality is not what it seems at first sight, defying all of your understanding of the world to arrive at the truth, it's not easy I know. But also don't deny everything that seems to defy your intuition.
Lord Tudraska
Lord Tudraska ヶ月 前
If we put a giant ring or band around the planet at 100km up, would it stay in place? Could we use it to spring objects into orbit without thrusters?
Edwin Michael
Edwin Michael 2 ヶ月 前
@wackoguywatch okay, I know it's been a year since you posted this comment... But here's what happens: when you instantly remove the surface underneath them after they jump over their respective surface, they're no longer under the gravitational field and are not getting accelerated - which basically means they are in an inertial state and are following the straight line path; but to us (from a different perspective like you said) they'll look like they're stationary masses in the outer space and there's no gravitational force or acceleration acting on them since there's no planet around them anymore. Well, I don't know if that response was comprehensive, but that's what I think would likely happen. And if I'm wrong about anything, please do let me know so we can all learn together.
George Ginsburg
George Ginsburg 2 ヶ月 前
I have a feeling that when people experience Vertigo, they’re actually sensing the acceleration through space/time. 😃
dav snow
dav snow ヶ月 前
At around the 17 minute mark, I had this really strange feeling of inertia enveloping my being. Lucky I could *feel it,* because there's no way I wanna *observe it.*
Cameron Thomas
Cameron Thomas 11 ヶ月 前
I’ve never understood the concept of bending space time around masses until this video. And now it makes sense how light gets trapped in black holes despite having essentially no mass
Gamer Dio
Gamer Dio 10 ヶ月 前
@RandomThings Interesting idea. May I ask, where's your degree? Facebook doesn't count, of course.
Gamer Dio
Gamer Dio 10 ヶ月 前
@Earl Lozano Photons do not have mass. The full equation is E² = (mc²)² + (pc)². Light has momentum, like all waves, but it doesn't have mass
Scott Rackley
Scott Rackley 10 ヶ月 前
@JWjustJW Incorrect
VanGilder Michael
Great explanation. Now do (anti-gravity). the two (mass) on each side of the equation, being the same. They cancel out. I had it all in my head, and it also took a huge amount of energy on the one side. I mean, huge (like a Tera-watt kinda huge). But it does work.
VanGilder Michael
​@Richard Palocsányi I really like your idea. First thing, Come to terms with yourself that "nobody", absolutely "nobody", is going to agree with you when your findings are in. And if you do a good enough, "dumbing it down" where people can understand. Then they will taunt you and try to change your mind. Don't change your stance. BUT, you are taking this the HARD way. DON'T set out to prove "gravity is not a force". That is not the right premise (although it would work, just a lot harder). Set out (what IS a force). And how (whatever definition you came up with) does not define gravity. (huh)? Then show how gravity is something the system came up with to explain away what their little eyeballs are viewing. And they make their imaginary definition ambiguous enough that people actually believe that horseshit. And then (the people) will not even peruse (anti-gravity). Because if the people could wield that one (their little plan would need to be changed). See your project is a LOT more than just the science side. Your proof is going to delve into the Kabbalah and (world domination) and so much more. Better not take it "TOO" far I guess. I did, I woke up dead in a hospital. yup I got a visit. So, all that is a good (outline) of all the BIG points that I chose. It went to big places. Just take what I got as a draft, and go with it. Dig down where you want hardest. Mine took a whole year. You are probably not want to spend that kind of time. Unless you are doing this for "you". And you have your entire life to spend. Go get em' tiger.
Richard Palocsányi
hello im trying to make a project to school about "Why Gravity is NOT a Force" but i cant find the quation he mention in his video so if you know were can i find could u tell me pls ty :)
David Schrecengost
Here is something I am really having trouble wrapping my head around. If there is no force pulling or pushing objects towards the ground, then why is there a need for a spaceship to reach escape velocity to get into outer space? I understand that a warped straight line can point you right back at the ground. What I don't understand is what is to prevent you from constanly correcting your path to escape the earth's atmosphere even though you are traveling at 5 miles an hour. It is after all only empty space/time you are traveling through. Since the only force you should be fighting is friction from the air. The the higher you go the easier it should get.
David Schrecengost
@MOPC Linguística The question is why does it need to travel at a specified escape velocity at all?
MOPC Linguística
the spaceship is not accelerateing to escape velocity, it's decelerating to it.
PoonDaddy99 ヶ月 前
growing up I had a theory that gravity on earth was caused by it's rotation on it's axis and it's movement through space via it's orbit around the sun. Of course I didn't have any proof and when I was told it was a force all it's own I just dropped the theory. Even if I'm wrong, your video has sparked interest in my original theory and the following question: if the earth stopped rotating and/or stopped moving through the solar system via it's solar orbit would we no longer be pulled to the ground and instead float upward?
XxAbdulMxX ヶ月 前
I don't think we would. As he showed in the video the rocket heading towards a large planet would still be pulled towards it because it curves space time. A good question would be, why does matter cause space time to curve and if gravity is an illusion, do the laws of gravity therefore apply in some part to space time vs matter
aarqa ヶ月 前
Great! I'll just let my physics professor know that gravity doesn't belong in a force diagram, I'm sure he'll _really_ go for that.
Narf Whals
Narf Whals ヶ月 前
Well if you really wanna excite him tell him that forces don't exist _at all_ and are just emergent effects from fundamental interactions.
Flame P
Flame P 年 前
As a Harvard Neuroscientist, here's another mind-bending gravity-related thought. When you rotate your head, you are NOT in control of the primary directionality of your eye movements under most circumstances. Try this. Keep your head still and look at your finger while you shake your finger left and right; your finger will look blurry due to motion blur. Now, instead, keep your finger still and look at it while you simultaneously shake your head left and right, which will demonstrate - in this situation - that you are still able to maintain a stable image of your finger. This is because your gravitationally-influenced sense of your head in space - your vestibular system - has a hardwired reflex to move your eyes in the opposite direction of your rotational head movements. This vestibular-ocular reflex (VOR) ensures automatic dynamic stabilization of images during head movements. You are not consciously doing this, and you can not consciously override it. The VOR is truly a reflex and, interestingly, does not depend on vision. During head movements, you will still have a strong VOR if you are in the dark or if you have your eyes closed. Your VOR originates from your vestibular system, which is located in your inner ear right next to your cochlea - your organ of hearing. Your vestibular system for rotational head movements consists of a series of three fluid-filled semicircular canals that have little "hair" cells inside the canals. When your head moves up-down (pitch), left-right (yaw), or shoulder-to-shoulder (roll), fluid inside the corresponding semicircular canal flows. This head motion-induced flow bends the hair cells within the canal to ultimately send electrical impulses to your hindbrain. These electrical impulses - encoding head movement - then talk to parts of your brain controlling eye movements, which connect to your eye muscles to reflexively move your eyes in the opposite direction of your head movement. So be thankful that your sense of your head in space - your vestibular system - takes care of maintaining a stable image of the world even when your head bobs around as you walk. Otherwise, walking would be a blurry journey of craziness. Videos coming soon.
Blake Schreurs
As a VR Researcher, this is extremely important for VR games (and even for some people playing games that don't rely on VR). The vestibular system often drives the ocular system, via the VOR, and the reverse is not true. However, as humans we are very (very) used to the two systems being in synch. If your vision system detects movement (especially in the peripheral vision) that the inner ear doesn't feel (say, from a roller coaster simulator or too much head bob in a game) OR if your inner ear detects motion that your visual system doesn't pick up (say, from a VR headset that reacts too slowly), a great many people will have feelings of vertigo or illness. Interestingly, where VOR is a pure reflex, the feelings of nausea are not, so some people never experience them, other people only have them under certain conditions, some people can get used to the disconnect, and some people get uncomfortable strongly and reliably enough that we're not sure if they ever could get used to the sensation. Many of these effects can also be cleanly mitigated by good hardware and careful selection of experiences (where the player's body is in full control of all forces acting on the body). (All of this, of course, assumes a healthy and typically wired body).
Chahat Singh
Chahat Singh 年 前
You got an element named after you?
Paul Regeer
Paul Regeer 年 前
No, there must be another explanation. Yours rings false.
Alfazulu FALCONPUNCH foxtrot
Wow. I just keep learning stuff from other peeps. Thanks
Florida Man
Florida Man 年 前
science is boring
Olle Olsson
Olle Olsson ヶ月 前
Great video, super interesting! To us, living in curved space time is normal cause that is all we've ever known (unless you fall of roofs a lot). All of our experiences and experiments are thus biased and we cant trust our judgement.
Dylan Evans
Dylan Evans 12 日 前
A lot of the analogies in this video appear to make sense at first blush, but the question that was in my mind the whole time was how this works for the mass on the *other* side of the object exerting force. If there space ship had another chamber on the bottom side, and there was another man in there standing the other way up then he would not also feel the 1G force pushing him down - he would instead find himself collapsed on the 'roof' of the rocket... In 'Earth' terms the analogy would seemingly see everyone on earth fly off into space whenever they were on the 'bottom' side of the earth moving through spacetime. I feel like maybe this was meant to be explained at 10:17 - but this is one point where we delve into a formula that does not help the average Joe understand the subject at all. Although Veritasium seems quite excited by the prospect of what he just explained - to me it made no sense at all.
Angus Uchiha
Angus Uchiha 14 日 前
i know this video is millions of years old. but i think about it pretty regularly. and thinking about it recently i came to a conclusion. namely: this doesn't mean Gravity isn't a force. this just means it's effects can be replicated using acceleration.
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