Combining Time Dilation from velocity and gravity

In summary, if a stationary observer is watching a spaceship travel near the speed of light and close to a massive black hole, the time dilation from the relative velocity and gravity of the massive object are significant. Assuming the ship is moving at 0.866c, for every hour that passes for the ship's astronauts, 2 hours pass for the stationary observer according to special relativity. Additionally, if the ship is close enough to the black hole, for every hour that passes for the ship's astronauts, 2 hours pass for the stationary observer according to general relativity. The combined effect is multiplicative, meaning that in 1 hour of the stationary observer's time, they would see stationary clocks at the ship's position tick 1
  • #1
edgepflow
688
1
Suppose a stationary observer was watching a spaceship travel near the speed of light and close to a massive black hope so that time dilation from the relative velocity and gravity of the massive object are significant.

Assume that the ship is moving at 0.866c so that for every hour that passes for the ship's astronauts, 2 hours pass for the for the stationary observer per special relativity.

Now also assume, that the ship is close enough to the black hole so that for every hour that passes for the ship's astronauts, 2 hours pass for the for the stationary observer per general relativity.

So the question is: what would be the combined effect?

P.S. I meant to post this in the Relativity Forum!
 
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  • #2
edgepflow said:
P.S. I meant to post this in the Relativity Forum!

Moved
 
  • #3
what would be the combined effect?
So in 1 hour of your time, you see stationary clocks at the ships position tick 1/2 hour.
They see the ship clock tick 1/4 hour - and so do you.
 
  • #4
Ich said:
So in 1 hour of your time, you see stationary clocks at the ships position tick 1/2 hour.
They see the ship clock tick 1/4 hour - and so do you.
Thanks for the reply Ich. It looks like the combination is multiplicative. I also noticed this under Similar Threads that discusses this.

https://www.physicsforums.com/showthread.php?t=299318
 

FAQ: Combining Time Dilation from velocity and gravity

How does time dilation from velocity and gravity combine?

Time dilation from velocity and gravity combine through the principle of relativity, which states that the laws of physics are the same for all observers in uniform motion. This means that time dilation from velocity and gravity can be thought of as two separate effects that occur simultaneously and independently of each other.

What is the formula for calculating combined time dilation?

The formula for calculating combined time dilation is t' = t / (1 - v^2/c^2)^(1/2), where t' is the dilated time, t is the original time, v is the velocity, and c is the speed of light. This formula takes into account time dilation from velocity and gravity by including the velocity term in the equation.

Does the strength of gravity affect time dilation from velocity?

Yes, the strength of gravity does affect time dilation from velocity. This is because gravity curves space-time, which means that objects in stronger gravitational fields will experience a greater curvature of space-time and therefore a greater time dilation effect.

How does time dilation from velocity differ from time dilation from gravity?

Time dilation from velocity and time dilation from gravity differ in their causes. Time dilation from velocity is a result of an object's motion through space, while time dilation from gravity is a result of an object's position in a gravitational field. Additionally, the effects of time dilation from velocity and gravity can be calculated separately and then combined using the formula mentioned above.

Can time dilation from velocity and gravity be observed in everyday life?

Yes, time dilation from velocity and gravity can be observed in everyday life. For example, astronauts on the International Space Station experience a slightly slower passage of time due to their high orbital velocity. Similarly, objects closer to massive bodies, such as a clock on Earth's surface compared to a clock on the top of a mountain, will also experience a slight difference in the passage of time due to gravity.

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