# If time stops for an object, does that object feel gravity?

As far as I understand The GTR, it is said that Mass bends space-time which causes gravity. So every Mass in this universe is flowing through space-time example earth is moving along with space-time and it is cycling around the sun because of the curvature created by the sun.

My question is if time is stopped for an object does that object still flow through space-time? For example consider - Hypothetically if I travel exactly same as light speed now my time is stopped, So i should not move along with space-time in fact I should not feel gravity. If I don't feel gravity then why photon is attracted to space-time warp since light's time is stopped?

Sorry if I got the whole idea of GTR as wrong, indeed if I am please guide me in right direction.

• Photons (and all zero mass particles) move at the speed of light. For these particles time "doesn't advance". Yet photons do 'feel' gravity (we know for sure that the sun deflects photons). So your reasoning is incorrect. – Johannes Jul 24 '13 at 13:00
• that's what my question is, if time is stopped why it is still moving through space-time curvature ? it shouldn't follow the curvature. – FosterZ Jul 24 '13 at 13:03
• The time a particle experience (its aging) is dependent on the path taken. A photon follows a path that yields zero aging. That happens to be a path that bends around heavy objects. – Johannes Jul 24 '13 at 13:08
• @FosterZ : The time $t$ is not stopping for a photon, it is its proper time $\tau$ which is stopping. You have the relation (in units $c=1$) $0 = d\tau^2= dt^2 - d \vec x^2$ – Trimok Jul 24 '13 at 17:46
• no it should not be down-voted, IMHO. The distinction between space time and everyday experience is not trivial. We experience time while traveling almost entirely through space. We experience an acceleration we call gravity that moves us over time through space. A photon is already maximally accelerated. So when one travels entirely through space at the speed of light one would not feel any acceleration and so would not experience gravity. TS not scientific to attribute a state of mind to a photon, but it can become an observable in spacetime along a worldline. – user12811 Jul 24 '13 at 21:38

## 2 Answers

that's what my question is, if time is stopped why it is still moving through space-time curvature ? it shouldn't follow the curvature

You're not "picturing" spacetime and world lines correctly. The world line of an object, even a massless object, is a path through spacetime; it is a locus of events that are the past, present, and future of the object.

If an object "stops" in spacetime, as you seem to be suggesting, it no longer exists.

• ok, so it is like spacetime path does not have stops, it does not matter if an object moves slow or faster than speed of light it will always go through the path of spacetime, is it correct ? – FosterZ Jul 24 '13 at 13:31

The speed of light wouldn't stop time but make it extremely slow. After u have traveled the distance light travels in a sec then you will pass 1 second in space time assuming you are still whole and have not turned into a photon which would break so many rules.

• No, this is not how special relativity works. In the reference frame of an object moving close to the speed of light (the reference frame of light does not exist), time passes much slower. – Martin Jun 28 '15 at 12:39