Undergrad Would Gravity Exist Without Inertia?

[Tiago]

Hello,

Let me explain my question. We know from GR, that gravity is just something (planet, light, etc) following a geodesic path through distorted spacetime. But that's just because everything is still in motion from the big bang, traveling at the speed of its own inertia.

So let's assume, just for the sake of argument, that EVERYTHING in the universe stopped moving. Impossible of course, but if that were to be true, planets and stars wouldn't just fall to each other because of gravity, right? Gravity wouldn't exist. We would probably stay in the ground, but feeling weightless, right? Gravity is not a force of attraction, just a distortion of our path through spacetime.

Is this correct?

Thanks

 

[russ_watters]

No, sorry, it is not correct. Since motion is only meaningful relatively, between two objects, the premise itself is wrong: you're already motionless with respect to the Earth, which doesn't impact your gravitational interaction.

 

[Dale]

Even if you stop moving through space you are still moving through time. Remember, GR is about curved spacetime, not just curved space.

 

[Hornbein]

Hello,

Let me explain my question. We know from GR, that gravity is just something (planet, light, etc) following a geodesic path through distorted spacetime. But that's just because everything is still in motion from the big bang, traveling at the speed of its own inertia.

So let's assume, just for the sake of argument, that EVERYTHING in the universe stopped moving. Impossible of course, but if that were to be true, planets and stars wouldn't just fall to each other because of gravity, right? Gravity wouldn't exist. We would probably stay in the ground, but feeling weightless, right? Gravity is not a force of attraction, just a distortion of our path through spacetime.

Is this correct?

Thanks

Hmmm. If everything stopped moving, I daresay there is no such thing as time. GR assumes time, so it does not apply in such a situation.

 

[Orodruin]

Hmmm. If everything stopped moving, I daresay there is no such thing as time. GR assumes time, so it does not apply in such a situation.

This is pure speculation and has absolutely nothing to do with real science. The correct answer has already been given. Please do not reply to post with speculation when you do not know the answer.

 

[Legolaz]

Times always tick(always exist) even if one could travel the speed of light. It is space that bends.

 

[Orodruin]

Times always tick(always exist) even if one could travel the speed of light. It is space that bends.

This is also not true. General relativity deals with curved space-time. Both space and time are involved in this. For any observer, elapsed time can always be computed by computing the proper time. In GR there is no such thing as a universal time.

Since this thread has started to attract responses with personal interpretations seemingly based on nothing but popularised science and the OP has been answered, I am closing it.