# Equivalence principle, time and gravity

## Equivalence Principle

Einstein made the small observation that gravity in an inertial frame and acceleration in a non-inertial frame feel exactly the same.
So one could say that the effect of gravity on your body feels equivalent to the effect of an accellerating object pushing you away from the center of the earth, radially outwards. Being that you are standing on the ground, it’s the same effect we would observe if earth’s surface was accelerating away from the center of the earth, which, of course, it doesn’t… Or does it?

## Hyperspace?

To entertain this idea, we have to consider movement in a 4th dimension. Since we can not observe any hyper dimension using any physical apparatus, what can we do? The answer comes from a fictional book which was written 50 years before Einstein’s discoveries. The book was “Flatland”. In the flatland, there are 2-dimensional residents like the circle, triangle and square. These residents do not know that a third dimension exists. One day they see a dot appearing somewhere. Slowly this dot becomes larger and larger, until one day when it suddenly disappears. What appeared to the residents as a dot changing size was in fact a cone passing through the flatland. Flat-landers did not know the third dimension in which the movement was happening but they did observe this passage as a function of time.

## Black Holes, yet again

Near a black hole’s event horizon, the rate of elapse of time becomes zero that is clocks stop ticking. Now the question is: is gravity making clocks tick more slowly or is time dilation creating gravity or are both deeply intertwined?

## Rethinking acceleration

Imagine you are a stationary observer on the surface of the earth. In reality, you are not actually stationary because the earth is spinning. This spin is giving you a constant change of direction even though you are at a constant distance from the center of the earth (we are assuming earth to be a perfect sphere).

Wait! Is it this torque which is creating gravity? Close, but no. In fact, the truth is the complete opposite. This spinning motion actually tries to throw objects away from the earth (centrifugal force) not towards it and is very small compared to gravity (around 0.35% at the equator).

So what is causing gravity? Einstein said that the presence of massive bodies create curvatures in the fabric of space-time and that leads to gravity.

## Is time-dilation exclusive to accelerating frames?

Mystics in the deep states of meditation feel the same time dilation concept. Let’s just assume this to be true for now. A mystic is not sitting in an accelerated frame going from place A to place B. So what is causing this time dilation?

It is the consciousness at play here; as it moves from the physical realm to the non-physical realm, time slows down. Does consciousness not face the speed of light limitation? Maybe there is a deeper, yet-to-be-discovered concept whose projection in the physical space is speed?

## What is time anyway?

We talked so much about time but what it is in reality? Is it simply a state machine. Think of a realm in which nothing changes. Nothing gets created, nothing gets destroyed. In short, no state exists or changes. There is no need of time there.