Why Gravity is NOT a Force

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Veritasium

Månad sedan

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 SVfrom 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
svfrom.info/round/ILl8ozWuxnFYXIe2svjHhg

Kommentarer
Veritasium
Veritasium Månad sedan
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.
John Mpjkken
John Mpjkken 10 timmar sedan
@wackoguywatch If you removed the earth, then wouldn't you have also removed the source of gravity? Then wouldn't the two men just float randomly in space where they jumped off?
Momchil Andonov
Momchil Andonov Dag sedan
So what about this video contradicting your claim that there are no gravitational waves? svfrom.info/history/video/mdOhl7Gyvat9aZE Oh by the way - you uploaded the other video as well!!!
K P
K P 2 dagar sedan
@Des Troya Try this instead: svfrom.info/history/video/p9Wwm4HOqLqSjsQ
K P
K P 2 dagar sedan
Try this instead: svfrom.info/history/video/p9Wwm4HOqLqSjsQ
SigFregacazzi
SigFregacazzi 4 dagar sedan
This video is mind-curving!
Skrillex The
Skrillex The Timme sedan
The feeble feigned alley relevantly tempt because thailand dfly fade amongst a relieved cappelletti. graceful, outrageous cocktail
Ubeogesh
Ubeogesh Timme sedan
9:28 aha!
Perfect!
Perfect! 4 timmar sedan
8:55 Just curious If "Gravity is not a force" Then there should be no "N" or reaction force as it is a consequence of the "Gravitational Force".
Narf Whals
Narf Whals 24 minuter sedan
N is the electromagnetic force from the atoms in the ground pushing against the atoms in your feet. That is not a consequence of gravitational force, but what keeps you from following your natural motion through the ground.
Jay Bear
Jay Bear 4 timmar sedan
This is incredibly. Completely destroyed my former understanding. But this makes 100x more sense. Mind blowing.
Ellis Tomago
Ellis Tomago 5 timmar sedan
You say gravity is not a force. But is it not a force that curves spacetime? Let's say you could instantly eliminate a large massive object like the sun. Wouldn't local spacetime bounce back to flat, and the earth go sailing off into the cold dark cosmos, away from all the other planets, which are sailing off on their own?
Andrew Novion
Andrew Novion 5 timmar sedan
Where are you coming from with your theories? If you are correct perhaps you would be the next Newton, Einstein, no, better,... with your theories. (They are your theories right? I didn't notice any other credits.) Truest point of the video... "Thus far... logistically impossible to test [really?] … but, What you believe will happen reveals what you truly think about the nature of gravity..." Is this the double slit experiment? You going Quantum on us? If so, I guess, whatever you say bro! (As long as enough people believe it?)
Narf Whals
Narf Whals 21 minut sedan
This is Einstein's General Relativity.
Andrew Novion
Andrew Novion 5 timmar sedan
You have an assumption that "light travels in a straight line". Why would light not be equally effected by everything else moving?
Andrew Novion
Andrew Novion Timme sedan
@Moazzam Hussain yeah... due to Gravity.
Moazzam Hussain
Moazzam Hussain Timme sedan
It does bend actually. Earth, the sun and stars etc bend light. Smaller objects on earth can do that too, but that deviation is too small to be detected. Google the word "gravitational lensing"
Andrew Novion
Andrew Novion 5 timmar sedan
Over the planet (unless the earth is flat?) when "I" am being accelerated up, and thereby feeling the "illusion" of gravity... would not the person on the other side of the earth feel the exact opposite?
Andrew Novion
Andrew Novion 5 timmar sedan
Hmmmm... a little bit of knowledge.... :(
Andrew Novion
Andrew Novion 5 timmar sedan
LoL, "bent sheet analogy... objects "like" to fall towards the center of the well due to gravitational force, but in reality there is no gravitational force..." (So, why do objects fall down? Perhaps, better question, hat's what we freaking call gravity! (Still just a theory though.) Sorry, please elaborate your replacement of the theory of gravity (Newton-ish) and relativity (Einstein-ish) and as one of the 4 forces felt at a distance (Magnetism, Gravity, Large force, Small Force [Atomically])... I honestly want to know, sounds like your a bit closer to the theory of everything...
Andrew Novion
Andrew Novion 6 timmar sedan
His path appeared curved due to gravity, but it wasn't... he didnt notice his change in acceleration or course???!!!! Until you admit that he crashed into the planet! ... wtf?... two people traveling on a sphere get closer and closer together, due to gravity?!!? Um, no. To people traveling from different points to the same destination probably get closer to each other without the help of gravity... :( I thought you were gonna be smart and stuff...
Narf Whals
Narf Whals 18 minuter sedan
They get closer because the space is curved. Which is exactly what gravity is.
loveto playtu
loveto playtu 6 timmar sedan
My response to your question at the end @veritasium if a falling electrically charged particle emits radiation then every electron in every atom would emit radiation all the time. This implies it would lose energy or give us an infinite supply of energy as radiation. We know this does not happen. We do give off radiation or thermal radiation based on the amount of vibration or internal kinetic energy. Here perhaps is the clue. When atom vibrate then they are exerting a force on other. So what happens to the electrons now are they still in free fall ? I suppose they are but now as one atom comes close to another a collision may take place there fore ending a free fall. i.e. two electrons may collide. Bam, now the electrons are decelerating and again accelerate as they move away from each other. Now out comes the radiation. Hence higher the temperature more the collisions and more the radiation. Black body radiation explained. Einstein was right !!!!!
Vadercon
Vadercon 7 timmar sedan
So what is happening to a balloon filled with a lighter than air gas (Helium)? Is the balloon, with no meanns of propulsion, moving faster than teh speed of the Earth through space?
Vadercon
Vadercon 7 timmar sedan
So what is happeningSo what is happening to a balloon filled with a lighter than air gas (Helium)? Is the balloon, with no meanns of propulsion, moving faster than teh speed of the Earth through space?
Xeno Bardock
Xeno Bardock 9 timmar sedan
Gravity is gradual cancelling of force. The exact opposite of increasing of force.
ameer kofahi
ameer kofahi 13 timmar sedan
11:00 “My dear, here we must run as fast as we can, just to stay in place. And if you wish to go anywhere you must run twice as fast as that.” ― Lewis Carroll, Alice in Wonderland
Andrew RollOut
Andrew RollOut 15 timmar sedan
Gravity's not a force. As 12:21 shows - Gravity's just a habit ;-)
Steven Strittmatter
Steven Strittmatter 16 timmar sedan
If gravity is not a force, then what are gravitons?
mark Tomas
mark Tomas 17 timmar sedan
maybe earth is flat and flying up
savindacooray
savindacooray 18 timmar sedan
When u love math and science as a kid.. and turned an alcholic.. and still you enjoy veritasiam
Raz P
Raz P 20 timmar sedan
Loved that edit
srihari vaila
srihari vaila 20 timmar sedan
Nice video 7:20 This Rocket example which is in straight line motion acclerating in 1 direction with a=9.8m\s 2 creates weight force on the astronaut just like in earth . Now imagine earth in 3d To create weight force on all the objects which are their on the surface of the earth that is . To exist a=9.8m\s^2 on all the points on the earth surface . The earth must be accelerating in many directions . Nice video .
srihari vaila
srihari vaila 14 timmar sedan
@Narf Whals Ho I havent seen the pinned comment thanks for telling me . Got your point .
Narf Whals
Narf Whals 17 timmar sedan
It doesn't need to move, only to accelerate. He explains what it means to accelerate while standing still in the pinned comment.
FURYUNLEASHED
FURYUNLEASHED 21 timme sedan
But gravity is a force. It's the force that curves spacetime, as far as we know.
Narf Whals
Narf Whals 17 timmar sedan
Spacetime is not a material that you deform using a force, as far as we know. Objects do not exert a force on spacetime and spacetime does not exert a force on objects in it.
Cinematic Laboratory
Cinematic Laboratory 23 timmar sedan
I think gravity is a fabric.
Sod Almighty
Sod Almighty Dag sedan
Horseshit. "Feeling like you're not accelerating" =/= "not accelerating".
Deep Space - Programming Tutorials
Deep Space - Programming Tutorials Dag sedan
You're really boiling my brain.
Peter Martinez
Peter Martinez Dag sedan
So a more accurate name for this video would be “gravity is not a force when your reference point is yourself”
Andy Hay.
Andy Hay. Dag sedan
yes the globe just floats in space because. Science is guess work, when people no longer die in trying stuff. Thats science. Magnets dudes.
Papercraft Shikhrrr
Papercraft Shikhrrr Dag sedan
Dislikes by flat earthers
Lav Rawat
Lav Rawat Dag sedan
Why we Feel to fall in opposite directions of force on a curve road while moving in a vehicle. 🤔
Lav Rawat
Lav Rawat Dag sedan
@Narf Whals thank you 🤘
Narf Whals
Narf Whals Dag sedan
When the car turns your body "wants" to keep moving in a straight line. So it falls into the outside. The force you feel is towards the inside.
Abdillah Sahib
Abdillah Sahib Dag sedan
So what the weight meter do? Why my weight different with other? If there is no gravitational force?
Narf Whals
Narf Whals Dag sedan
It measures how much force it takes to push you off your geodesic. That is related to your mass.
Adwaith Reddy
Adwaith Reddy Dag sedan
Do one thing tell the person on Mars to send his time and blast Mars at the same time (Assuming it takes 20 mins for light to travel from earth to mars and instantaneous for light to travel from mars to earth ) Earth send message at 12 :10 Mars recieves at 12 :30 but the person thinks it is at 12 :20 and send a message that the time is 12:20 and instantaneously blast Mars Now if earth saw mars in real time earth will see Mars blast at 12 :30 and earth will also receive a message that it is 12: 20 and hence proved that the previous assumption was correct that it takes 20mins for the light to go to mars and instantaneously comes back to earth
Ty_Braek
Ty_Braek Dag sedan
3:39 But why doesn’t the spaceman feel any change when getting pulled toward the planet? You said he is going faster which means acceleration. If you passed close to a planet wouldn’t you accelerate and the objects in the spaceship move as well?
Narf Whals
Narf Whals Dag sedan
What can he feel? Everything inside the spaceship is falling at the same rate. There is nothing any instrument could register without looking outside.
BIGBUNKYGO
BIGBUNKYGO Dag sedan
Hi I got stomach flu so I will not be live tonight and not tomorrow Sunday I should be good enough again to come back, but we'll see. If not I will give myself more time. I will stay in bed and rest. I know it's disappointing, but health is important and I hope you are all well. Stay healthy guys and take rest when your body indicates it. It might be hidden, so take your time to listen to your body. Rest could even be stopping 1 hour earlier today. It might not only save you from crashing at a crucial point, but also in the long run, it will improve your overall well being 🙏 I'll keep you updated here in the community posts ! Heleen
Evren Saygın
Evren Saygın Dag sedan
So.. you are moving on a geodesic because there is gravity?
Narf Whals
Narf Whals Dag sedan
You are moving along a geodesic because that's what objects do that have no forces on them. The geodesics get pointed towards earth because of spacetime curvature. Gravitational attraction is a result.
Shubhojit Das
Shubhojit Das Dag sedan
If gravity is not a force, then what about blackhole concept?
Narf Whals
Narf Whals Dag sedan
A black hole is a surface at which all geodesics point inward.
BenZ CGI
BenZ CGI Dag sedan
I'm not going to suicide i'm going to be an inertial observer
SUDHANSHU SHEKHAR
SUDHANSHU SHEKHAR 2 dagar sedan
What if we are currently in a blackhole?
Kamal Raj Sharma
Kamal Raj Sharma 2 dagar sedan
Dear sir, I just wonder sometimes that what would be the time difference between being on earth and being nearest possible to our galaxy's supermassive black hole.
מטיה
מטיה 2 dagar sedan
How does one accelerate at "10 Gs" if "Gs" in fact do not exist?
Edwin
Edwin 2 dagar sedan
Fun fact: A gyroscope's orientation remains constant relative to any inertial reference frames.
Ken Wolf
Ken Wolf 2 dagar sedan
been working hard on that very problem you raised at the end of the video; it's hard, but it's harder to resist the temptation of discovering a new law of physics (in attacking that problem).
Ken Wolf
Ken Wolf 20 timmar sedan
@Narf Whals nah, curvature is a local invariant of spacetime (a differential manifold endowed with a metric compatible connection); thus if the spacetime is curved, which means its Riemann-Christoffel tensor does not vanish, you can't transform it away. this problem is really beyond Rohrlich's expertise.
Narf Whals
Narf Whals 23 timmar sedan
@Ken Wolf In general relativity spacetime is always flat _locally_ . But the resolution qualifies for global curvature. "This manipulation is not a Lorentz transformation, because the two frames have a relative acceleration. Instead, the machinery of general relativity must be used."
Ken Wolf
Ken Wolf Dag sedan
@Narf Whals that's on flat (Minkowskian) spacetime; by the way, even in flat spacetime, the problem of electromagnetic radiation reaction is still unsolved.
Narf Whals
Narf Whals Dag sedan
en.wikipedia.org/wiki/Paradox_of_radiation_of_charged_particles_in_a_gravitational_field
Kasey Baack
Kasey Baack 2 dagar sedan
Good animations ❤
New Account
New Account 2 dagar sedan
Very confusing exponation waisted my time horrible. Make more eaire please if you really understand what you are talking about ?
Louis Lepage
Louis Lepage 2 dagar sedan
That's heavily thinking outside the box. Love it.
D Bradford
D Bradford 2 dagar sedan
What about weighing less at the equator? Is this part of the equation?
Kayla Skilling
Kayla Skilling 2 dagar sedan
The reason Einstein and others like him are geniuses is because they imagine things the rest of us need help to imagine.
We Like Boogers
We Like Boogers 2 dagar sedan
Einstein also said: If you can't explain it simply, you don't understand it.
Lonnie Ralston
Lonnie Ralston 2 dagar sedan
And that proves that taking the math to a final conclusion ends up with absurdity.
Michael Harto
Michael Harto 2 dagar sedan
"new way to visualize general relativity" helped me understand gravity a little bit more.
Shashi Bhushan Rana
Shashi Bhushan Rana 2 dagar sedan
One thing I am always confused of space-time is that, how the space is just like a plane, if we put some objects on it, it bends it downwards. In space how would we say which is downward direction ? How can all the objects in space lie on same plane ?
Narf Whals
Narf Whals 2 dagar sedan
That is why the stretched sheet analogy is terrible. Not only does it explain gravity by using gravity, it also gives the impression that space bends into some other space. It does not. Forget everything about that. Time and space bend into themselves and each other. By far the biggest reason for gravitational attraction is only time dilation around massive objects. svfrom.info/history/video/dpiJmqLXtsl7ssg
Man From The Moon
Man From The Moon 2 dagar sedan
That was amazing.
Adobe Reviews
Adobe Reviews 2 dagar sedan
This video is a masterpiece. The best explanation of gravity on the internet currently.
ayuxh
ayuxh 2 dagar sedan
from reddit 🖐
brupper E
brupper E 2 dagar sedan
I'm here from reddit
officialjkenn
officialjkenn 2 dagar sedan
bruh he really got bodied by an old man at 12:28 lmfaoo
Akash Advaith
Akash Advaith 2 dagar sedan
Then what about gravitational waves...? And why space-time is curved around masses.
Narf Whals
Narf Whals 2 dagar sedan
This theory predicted gravitational waves in the first place. They are waves of spacetime curvature.
Shawn Cabanes
Shawn Cabanes 2 dagar sedan
Question though, if gravity is a myth doesnt that mean that it should be easy get off the earth? Thinking that there is no force that bring you towards the the earth means that you should be able to “walk out” of earth by pushing the floor? Or am i getting this wrong? Since spacetime is curved in planets and you mean gravity is not there which means you can theoretically move away from the earth with little effort/force since there is no force counteracting gravity? Right?
Narf Whals
Narf Whals 2 dagar sedan
You'd have to move against the curvature, which requires a force.
steven king
steven king 3 dagar sedan
Is Gravity a chemical composition which is located in the core of the Earth. Can't we discover those chemical properties that creates gravitational force, we could create artificial Gravity for future spaceships
rafael mendez
rafael mendez 3 dagar sedan
Easy boy
Mitchell Walther
Mitchell Walther 3 dagar sedan
I guess you could test this by measuring the distortion of the moons orbit between the earth's spacetime and the spacetime of the sun.
Mitchell Walther
Mitchell Walther 3 dagar sedan
If it matches the natural escape velocity of the moon from earths orbit then it proves him right. If it doesn't there are unknown forces at work.
vespers_
vespers_ 3 dagar sedan
Forgive my dumb question. if gravity is not a force and orbits are simply due to curved spacetime what keeps the planets in stable orbits?
vespers_
vespers_ 2 dagar sedan
@Narf Whals Thanks!
Narf Whals
Narf Whals 2 dagar sedan
Basically Newton's first law. The orbits are inertial motion. Unless a force acts on the planets, they have no reason to deviate from them.
Devin Loew
Devin Loew 3 dagar sedan
All this proved to me was just how much of a genius Einstein was...
lymphy12
lymphy12 3 dagar sedan
So if there wore no objects in space there would be no graviry as there in nothing to be attracted to?
Narf Whals
Narf Whals 3 dagar sedan
Sure, but that has always been the case. Where would a force of gravity come from in an empty universe? There is no electricity in an empty universe either.
Daehee Kim
Daehee Kim 3 dagar sedan
*SPLAT*
ZER LA
ZER LA 3 dagar sedan
This video makes me jump out of the roof
it's ok
it's ok 4 dagar sedan
If earth is pushing to us one side then who is pulling those of the otherside ? !!!!!!!!!!!
Narf Whals
Narf Whals 3 dagar sedan
Earth is pushing "outward" in all directions. He talks about this in the pinned comment.
Danny Fernandes
Danny Fernandes 4 dagar sedan
Hello Veritasium! First of all, let me say THANK YOU! This was a beautiful video and perhaps the best explanation of what Gravity really is. I had earlier seen quite a few explanations but I really couldn't get my head around it. Your animations, esp. that of the ISS moving in a helical path through spacetime really threw some light in my understanding. But I still have a few questions 1) If gravity is due to curvature of spacetime, then shouldn't the passengers in an aeroplane experience no gravity - just like the astronauts in the ISS? After all, the aeroplane's surface is not exerting any force on the passengers, and the aeroplane is also moving at constant velocity relative to the earth's surface so it is not accelerating. 2) In your video, if an astronaut is travelling through empty spacetime, i.e. in an inertial frame of reference and it comes across a planet, then the astronaut's space ship begins to accelerate and an external observer sees the space ship bend towards (i.e. accelerate) the planet. So shouldn't the astronaut and everything inside his space ship now start experiencing gravity as the space ship's floor is now accelerating towards the planet?
Narf Whals
Narf Whals 3 dagar sedan
1) The plane _is_ accelerating or it would fall and it exerts a force on the passengers just like earth's surface(which is also accelerating). 2) Spacetime is still "locally flat". From inside the spaceship the astronaut notices no change unless he looks outside because everything inside falls at the same rate. An accelerometer registers no acceleration if all its parts move the same. Everything inside the spaceship is in inertial motion until it hits the ground.
MoCo MoCo
MoCo MoCo 4 dagar sedan
I really wish I had the intelligence to understand this.
Narf Whals
Narf Whals 3 dagar sedan
I don't think it's about intelligence but about letting go of a lot of things you thought you knew. That can be _hard_ .
Cosmin Lucacel
Cosmin Lucacel 4 dagar sedan
And I thought I understood general relativity
Phillip Probst
Phillip Probst 4 dagar sedan
So, if Einstein determined that gravity is not a force at all but, rather, the observed effects of objects moving on "straight" paths through "curved" space-time, could it be said that if gravity is a force after all, it's not a force acting on massive objects like the earth or apples but, rather, a force acting on space-time itself? E.g., the earth's mass exerts a gravitational force on space-time which curves space-time in it's vicinity, causing objects to travel on curved paths (orbits) as they pass by. 🤔
Narf Whals
Narf Whals 4 dagar sedan
Spacetime is not a physical fabric you can exert a force on. It is only the relationship of distances and angles between objects. Just geometry. If it helps you visualize better you can think of it that way, but that is not what the theory says.
Talhah Qureshi
Talhah Qureshi 4 dagar sedan
You thought I was a force But it was me DIO!
sonu jacob
sonu jacob 4 dagar sedan
After watching this i need to ask 3 questions. 1. how does Matter curve space time? 2. As the matter moves it must follow the curved space. but why cant the object stay still.why does it try to move in the curved space time? 3. what is the significance of space time if humans or other intelligent beings does not exist?
Narf Whals
Narf Whals 4 dagar sedan
1. That is what Einstein's Equations describe. In General Relativity there is no deeper "how" or "why". The relationship between spacetime's geometry and its content is fundamental. 2. There simply is no standing still in spacetime. Everything always has a velocity. If it is standing still in space it is moving at maximum velocity in time. Maybe you heard that "we are all moving at the speed of light" Because in spacetime our velocity vector _always_ has the magnitude c. It just gets turned between moving in space and moving in time. The more you move in space, the less you move in time. That is time dilation. 3. I don't understand the question, sorry.
NovaRanger
NovaRanger 4 dagar sedan
After seeing the video, So.. this is what it feels to be Mind f*cked (o.O)
gonira
gonira 4 dagar sedan
I get that what makes us fall is not a force per se, but the curvature of space-time around a massive object. BUT Isn't a "force" what causes this curvature?
Narf Whals
Narf Whals 4 dagar sedan
No. Spacetime isn't a physical substance you can exert a force on. Masses curving spacetime seems to be just a fundamental relationship.
RangQuid
RangQuid 5 dagar sedan
If the gravitational didn't exist, then why would the so-called "tidal force" show up when an object is in a strong gravitational field?
Mazeu
Mazeu 2 dagar sedan
@Narf Whals sry i missspelled previous question. There is one thing i want to know. When we send space probs to other planets we use gravitational whips. If there is only curved space inertia, that makes it look like acceleration. Why those object do not get back to original speed after they leave highly curved space when they come back out of it. Instead they actuly get greater velocity. Why?
Narf Whals
Narf Whals 2 dagar sedan
@Mazeu Inertia. Newton's first law says an object in motion will stay in that motion unless acted upon by a force. That is inertial motion. Inertial motion in flat spacetime is motion in what we know as a straight line. In curved spacetime a straight line is isn't what we think it is, so to us it looks inertial motion follows curves. Around earth, for example, straight lines are curved towards earth.
Mazeu
Mazeu 2 dagar sedan
@Narf Whals but what forces you to a certain point of the curvature then?
Narf Whals
Narf Whals 4 dagar sedan
Tidal forces happen when different parts of an object are on different geodesics. When you fall head first into a black hole, as you get closer your head will be on a different geodesic than your feet and try to move away from them. If the curvature is strong enough this can overcome the electromagnetic forces holding you together and you get "spaghettified".
aleksander Okonek
aleksander Okonek 5 dagar sedan
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.
Apurv Gandhi
Apurv Gandhi 5 dagar sedan
@veritasium - if gravity is an illusion, how do stars / black hole form. Have always heard that matter collapse under gravity force and stars are formed. Hope I am asking right question.
Narf Whals
Narf Whals 4 dagar sedan
Everything curves spacetime. Stars form from dust clouds in which little chunks curve spacetime to curve the geodesics of other chunks towards them. They form bigger chunks, which curve spacetime more and so on. Same with planets. Black holes form when the pressure inside a star is not enough to withstand the geodesic motion of the material. Like the earth accelerates you "up" the pressure inside a star accelerates the gas outwards. If the star dies and can't keep the pressure up all the material will fall inwards along the geodesics and increase the curvature close to the core. When the curvature is big enough that to move away from the star would require moving at the speed of light it is a black hole.
From Here
From Here 5 dagar sedan
I wonder if this has anything to do with what Impacts the creation of Wind.
MACH : Fist at light speed
MACH : Fist at light speed 5 dagar sedan
Extremely interesting subject! My another question is whether understanding the concept in this video will directly improve our everyday life. For example, will my boxing skill improve after understanding this gravity-acceleration thing? I don't know yet but I will try. Thank you so much Veritasium. ♡
Dávid Csonka
Dávid Csonka 5 dagar sedan
Derek. Here is a thought experiment for you: It is a hot summer day. You are sitting in a sailboat and you just steered it to running direction. Now this boat is really really good and efficient, so you are just travelling with the wind. Suddenly you feel uncomfortable... It is getting hot. Apparently at least. Why? Because you no longer *feel* the wind. For you, as an observer, who has a speed and acceleration of 0 relative to the wind, the wind does not exist. _Or does it......_
Akshat Jain
Akshat Jain 4 dagar sedan
Wow..
Lewis George-Cole
Lewis George-Cole 5 dagar sedan
If gravity does not exist then how is earth accelerating around the sun where is that energy coming from to accelerate the earth foward.
Narf Whals
Narf Whals 5 dagar sedan
The same way we fall to earth. Spacetime curvature. The earth follows a straight line through spacetime around the sun.
Alex T
Alex T 5 dagar sedan
Same is true in any field. Magnetic, electric, even floating on a river. If you're going downriver, you don't feel the force. But it's there. All a field is is an agreement that a particle, for some reason will act accordingly while in it.
Kirill Prymachov
Kirill Prymachov 5 dagar sedan
So, a question: If two bowling balls were floating in space at a distane from each other, completely stationary, and then the Earth appeared between them for several seconds and vanished again, would those balls continue moving towards each other after Earths disappearance or become stationary again? If they contined moving, then why? The Earth popping into existance didn't apply it's gravitational force to them because that force doesn't exist, it just bent space-time for a cuple of seconds, why would stationary objects continue moving then? Also why would they start moving in the first place? Their velocity was zero, so we can say they were moving along some line with a velocity of zero, Earth popping in would bend that line, but the velocity should still be zero, right? I'm not trying to disprove anything, just trying to understand it.
Narf Whals
Narf Whals 5 dagar sedan
There is no velocity zero in spacetime. If an object has no velocity in space then it has a lot of velocity in time and vice versa. Spacetime curvature turns the velocity in time into velocity in space. When the earth disappears it doesn't get turned back but the bowling balls continue on their paths.
8o8inSquares
8o8inSquares 5 dagar sedan
Does this change anything regarding magnetic force then?
Narf Whals
Narf Whals 4 dagar sedan
@8o8inSquares magnets act on moving charges, not just metal. Permanent magnets essentially have moving charges inside them. In the theory that treats electromagnetism with spacetime curvature charge is an additional dimension things move in. en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory
8o8inSquares
8o8inSquares 4 dagar sedan
@Narf Whals hmmmmmmm it's a bit questionable because magnets attract only metal, while spacetime curvature doesn't care about materials
Narf Whals
Narf Whals 5 dagar sedan
Considering that the magnetic force doesn't actually exist either, depends on what you mean. Special Relativity already explained the magnetic force as a relativistic effect of the motion of charges. But it is also possible to formulate electromagnetism in terms of spacetime curvature.
KnNY
KnNY 5 dagar sedan
So what about the people on the opposite side of the earth, why aren't they falling off?
Narf Whals
Narf Whals 5 dagar sedan
The earth's surface is accelerating outward in all directions _while standing still in space_ . He explains more about what that means in the pinned comment.
IDHWOF
IDHWOF 6 dagar sedan
wait if einstine theory was right and non moving charge is actually accelerating and radiating energy, FREE ENERGY????????
I am it
I am it 6 dagar sedan
ok one question arises for this explaination of gravity-- If earth is accelerating outwards at a rate of 9.8m/s2 then it would be expanding and we are having the same ratio of size of our with earth. which means we are expanding . Let take E as the rate at which we are expanding so as to remain same size ratio with earth. but for moon the acceleration is far much smaller than earth .so it would be expanding with acceleration much less than 9.8m/s2. Now if a person stay there he need very less expansion than earth. to remain same ratio of size with moon.so its expanding rate on moon = less than E. so if a person spends sometime on moon and come back to earth he would be much smaller than people on earth . And we know that it is not the truth!
Narf Whals
Narf Whals 5 dagar sedan
The earth's surface is accelerating outward in all directions _while standing still in space_ . He explains more about what that means in the pinned comment.
anywhere from
anywhere from 6 dagar sedan
too abstract, not fully understand yet
Rose Fahmida
Rose Fahmida 6 dagar sedan
This video is a masterpiece. The best explanation of gravity on the internet currently.
Berserk Berserk
Berserk Berserk 6 dagar sedan
7:55 Veritasum calling you FAT !!!
Shawn chew
Shawn chew 6 dagar sedan
Am i not getting this? But why would i feel like he is proving flat earther right
haha huhu
haha huhu 7 dagar sedan
I'm not really buying the star path being deflected at a point since the light goes everywhere equally, the observed star should be observable of the other side of the sun or making a halo around the sun
Narf Whals
Narf Whals 5 dagar sedan
@haha huhu The einstein ring only happens when the lens is exactly between us and the star and at the right distance. Not all light is always bent exactly to us from all directions. The Eddington experiment simply was not at the correct angle. At the bottom of the article are several references to einstein rings that have been observed.
haha huhu
haha huhu 6 dagar sedan
@Narf Whals this Einstein ring seems not happening in during that time and This Eistein ring is explaining only when the phenomena is happening but not explain why at that time it only observed a single star
Narf Whals
Narf Whals 6 dagar sedan
That happens en.wikipedia.org/wiki/Einstein_ring But you need to be at the right angle to see it.
Its All Good Games
Its All Good Games 7 dagar sedan
kim jung un approves
Gary Dumpleton
Gary Dumpleton 7 dagar sedan
The blaring omissions in Einstein's equivance is space. Which we know is not empty. See vacuum energy. .positron electron generation. And many others. So in gravity space is moving. How fast is it moving. G x t. Where t is life of the earth. 4.2 billion years. That's fast. So if positron and electrons are generated from space why don't they have the momentum from space. If space is not moving why don't the particles collide with our momentum. Maybe the casimir effect holds the answer. The space that is around us and between atoms is contained by the matter surrounding it. Kind Regards Gary
Lucas Anonymous
Lucas Anonymous 7 dagar sedan
Gravity *applies* a force. Not a force itself. There is a big difference.
un named
un named 7 dagar sedan
air resistance cries in the background
Narf Whals
Narf Whals 6 dagar sedan
Always inconvenient. Always ignored... We feel you, air resistance. We feel you!
Sven van Veen
Sven van Veen 7 dagar sedan
I understand the part that when I'm falling I am actually in a intertial frame of reference and everything moves up so it looks like I'm falling. The thing I don't understand is how can the earth be accelerating up in every angle. Or does it mean that we are accelerating at the exact same speed as the value of curved space time so that means our spatial coordinates are not changing therefore we are staying at the same position on earth. But then again I am not fully understanding how the earth is pushing me up in every angle. I would appreciate if someone could explain this to me.
Sven van Veen
Sven van Veen 6 dagar sedan
@Narf Whals thanks for the reply! I will take a look at the pinned comment!
Narf Whals
Narf Whals 6 dagar sedan
Basically correct. In curved spacetime you have to accelerate to stand still in space. The earth accelerates "outward" while standing still. Falling objects don't accelerate so they move in space. The earth just gets in the way. He talks about this in the pinned comment.
Władca Wymiaru
Władca Wymiaru 7 dagar sedan
Gravity is a water, and we are it it, like a fish that do not realize the water exist. And WHY the pancace becomes flat when spinned? It because water and other things insice have VISCOSITY!!! This is why all work, galaxies, solar systems, planets...and this field believe me has HUGE power! Farther you are, then stronger is that field...
s r
s r 7 dagar sedan
Ahh,Derek! Does that mean that all middle and high school physics teachers should be changing their curricula?
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