How do we know the speed of light is constant?

In special relativity, the speed of light is constant when measured in any inertial frame. In general relativity, the appropriate generalisation is that the speed of light is constant in any freely falling reference frame (in a region small enough that tidal effects can be neglected).

What do you think might happen if an object travels faster than the speed of light?

Time Travel Special relativity states that nothing can go faster than the speed of light. If something were to exceed this limit, it would move backward in time, according to the theory.

How does the speed of light affect time?

Changes to time and distance Perhaps one of the most famous effects of special relativity is that for a human moving near the speed of light, time slows down. In this scenario, a person moving at near light speed would age more slowly. This effect is called time dilation.

Can we reach the speed of light?

We can never reach the speed of light. Or, more accurately, we can never reach the speed of light in a vacuum. That is, the ultimate cosmic speed limit, of 299,792,458 m/s is unattainable for massive particles, and simultaneously is the speed that all massless particles must travel at.

Do objects moving at nearly the speed of light look distorted?

Given that already since Olaf Römer’s observations of 1676 it has been known that light propagates at a finite speed, it would have been possible more than 300 years ago to conclude that objects moving at nearly the speed of light must look distorted. Surprisingly, no such conclusions have been drawn in the framework of classical physics.

What happens to light when it travels through empty space?

In empty space, the wave does not dissipate (grow smaller) no matter how far it travels, because the wave is not interacting with anything else. This is why light from distant stars can travel through space for billions of light-years and still reach us on earth.

Why can’t light travel faster than the speed of light?

Because the light travel times resulting from the finite speed of light have not been taken into account.

What is the shape of the sphere moving at 95\% speed of light?

Figure 2: A sphere (a) moving at 95\% of the speed of light is contracted to an ellipsoid (b) as a measurement of its shape would show. Looking at the moving sphere, one sees it with an exactly circular outline, but rotated (c).

https://www.youtube.com/watch?v=fth5ZxhMcTE