General Relativity! Einstein's Equivalence Principle and the Curvature of Space-time | Doc Physics

Einstein had a knack for shaking things up. Accelerated reference frames are equivalent to gravitational fields, so a gravitational field can be viewed as acceleration, which leads to some really interesting gravitational effects on light. Light feels gravity.

[DocSchuster]

Thank you! Let's hope the USA kids step up the hard work!

[bwknowles]

I cant believe im understanding the gibberish you were speaking! I have finally studied enough about inertia and relativity to understand the language of this part of physics! Yay. Great vid too man it was awesome.

[subhasbagchi]

i liked this video...before man is awesome

[captaincomrade]

These videos are great for students. Even as a 9th grader i'm able to understand this despite only studying basic astronomy at school

[BTWPhysics]

The equivalence principle is actually wrong. I'm currently writing up a scientific paper showing undeniable proof.

[synapticmemoryseepage]

Excellent explanation and presentation!

[fisicaall]

So is it correct to say that mass objects are also attracted to light? Because of the equal forces of a gravitational field.

[GuyusSeralius]

I would think one could determine whether or not he or she were in a box resting within Earth's gravitational field or in a box being accelerated in space simply by dropping two objects. Drop the first from 1 meter high and the second from 2 meters high. In Earth's gravitational field, the first object should strike the floor in less time compared to the time it takes the second object to traverse a meter, since objects further apart have less attractive force. If you did the same within an accelerated box in space, both objects would traverse a meter in the same amount of time regardless of where they were released.

[MichaelHarrisIreland]

Its amazing but why is it considered there is some difference. I know if falling in a gravity field your legs would be pulled more than your head, not that you'd notice, unless you were 100 miles tall. I don't think falling in a gravity field is the same phenomenon as being accelerated down because one is pushing and the other pulling. I think there is no difference being accelerated up but falling back down in a gravity field as distinct from being accelerated down in space seems a different matter, (if you're hundred mile wide water balloon you would stretch towards the planet if being pulled but not so if accelerated) at least it seems to me. It's like to know more if possible, because I don't really believe that gravity pulls.

[professor]

I like the idea of free fall elevator !

[nikhafiz]

About the 2nd elevator with gravitational effect. The light should bend upward instead bending downward, because the elevator is accelarating down. Am i right?

[williambennett]

When this concept finally clicked for me I was so excited to explain my understanding to my old professor.
Hah! He said to me... Yeah it's relativity. Just so simple to him.
U should do a video explaining what world happen to a light particle if you shined a light when moving at the speed of light.

[syed_rezwan]

a huge fan of yours....your my new physics teacher....

[adosar]

Can you elaborate please a little more in 6:24?

[rfmvoers]

Thanks for this video. Thinking of the earth's gravity as a 'fictitious force',  one could imagine that the earth expands outward with a constant acceleration. But it's actually as if 3D space is 'falling' into the earth with a constant acceleration? Is that the same as the curvature of 4D space-time?

[gyrod]

The pressure of space tries to be everywhere, this pressure on stars, planets, etc. is gravity. The orbital paths around the Sun caused the bending of light. It's the shortest distance. When a supernova blows it has 2 opposing jets and a ring or 2 (D or F subshell). The jets (fliers, binary stars), the ring or two (planets and their orbits).

[gpcrawford]

Indeed they are equivalent except for a tidal effect given by a varying gravitational field . Gives us tides on earth spaghettification near black holes ( just don’t go near ). LOL . Can’t understand the underpinning mathematics differential geometry and all that who can! Even Einstein had to be taught it by his old uni nerdy classmate Marcel Grossman who also lent him his lecture notes so he could graduate and further found him a job at the Swiss patent office in Berne.

[atheistaetherist]

Every one of Einstein's gedankens is wrong. For example, re Einstein’s silly elevator/chest gedanken for supposed equivalence.

1. Hanging wts will hang parallel in accel, but will converge if in gravity.
2. Clocks will tick at same rate in accel, but will tick differently if at different altitudes if in gravity.
3. Photons crossing the room will all remain horizontal in accel, even tho the ray of light curves down, but photons will not remain horizontal in gravity, they will have a slope parallel to the curved traject if in gravity.

Re 3. Einstein’s elevator/chest gedanken for the equivalence of a curving ray of light in accel & in gravity ignores this lack of equivalence. If we apply Einstein’s gedanken to the bending of light passing a star then no photon passing a star would ever fall below the mid-line of the star. Hence there would never be a focus, hence there could never be a ring, or even a part-ring.

Every one of Einstein’s gedankens is wrong. His prediction of the doubled bending of light passing the Sun is a lucky guess. Likewise his prediction of rings. Likewise his prediction of Shapiro Delay. None of these are a legitimate prediction of any of his gedankens.

The only remnant of his GTR is the slowing of light near mass, confirmed by Shapiro Delay. We need to find the real cause of Shapiro Delay.

If i am kind i can give Einstein credit re the doubled bending of light passing the Sun. But we know that a mysterious half of it is due to Shapiro Delay (Dicke). Hence we need to find the cause of the other mysterious half (hint)(it is due to a psuedo-ballistic bending).

Re 2. I should add that all kinds of clocks must be affected differently by altitude & by velocity. Tests show that some atomic clocks behave nearnuff as per GTR. But we will find that GTR does not apply for most kinds of clocks, eg tuning fork & balance wheel clocks.

[Ptrckjsr]

he wrote Earf and i found that hilarious

[ryankeathley]

I don't get this argument. He says that an accelerated ref frame and a gravitational field are identical, hence gravity accelerates light. But at this point in my education, why can't I simply believe that this is an experiment that distinguishes accelerating frame vs gravity field.