# Calculating Absolute Velocity at 50% the Speed of Light

• ThinkThrice
In summary: S7r5GeIfZas. But the takeaway is that you would not be able to measure the difference in the speed of light between different reflectors on the perimeter of the shell.
ThinkThrice
In the spirit of this forum I should first announce:
-generally, I have no idea what I'm talking about but look for you folks to enlighten me.

Question:
If I am traveling at a significant fraction of the speed of light and I wish to know my current absolute velocity can I use the speed of light in different directions?

If I'm moving at 50% the speed of light in some direction
and I build a spherical shell with reflectors facing the center of the shell
and I stand in the center of the shell and move with the shell with a stopwatch and shine a light at reflectors all around me in my shell
1 - would i measure differences in the speed of light between different reflectors on the perimeter of the shell?
2 - if that's possible couldn't I measure my absolute velocity and determine the direction I'm travelling?

There's no such thing as absolute velocity; velocity is relative. (More precisely, any velocity less than the velocity of light is relative.)

Thanks for the response - blows my mind!

ThinkThrice said:
1 - would i measure differences in the speed of light between different reflectors on the perimeter of the shell?
2 - if that's possible couldn't I measure my absolute velocity and determine the direction I'm travelling?

The answer to #1 is "no", and therefore #2 is not possible.

Any observer who is moving at a constant speed is entitled to think of himself as at rest and everyone else as moving in the opposite direction. This follows from Einstein's two postulates of special relativity, and is confirmed by an enormous amount of experimental evidence.

Einstein's Theory of Relativity is based on two principles and one of them says "No matter how fast you are moving, the speed of light always remains the same for you i.e. c".
For example, if you are traveling at the rate of 2*108 m/s, relative to earth, then essentially, the relative velocity between you and the light should be 1*108 m/s. But it doesn't happen, light always travel at c and you see the light waves passing you at the same speed as you are in rest.
So, measuring the difference in velocity between you and the light waves (relative velocity between you and light) doesn't make any sense because it is always constant and is always equal to c...

ThinkThrice said:
In the spirit of this forum I should first announce:
-generally, I have no idea what I'm talking about but look for you folks to enlighten me.

Question:
If I am traveling at a significant fraction of the speed of light and I wish to know my current absolute velocity can I use the speed of light in different directions?

If I'm moving at 50% the speed of light in some direction
and I build a spherical shell with reflectors facing the center of the shell
and I stand in the center of the shell and move with the shell with a stopwatch and shine a light at reflectors all around me in my shell
1 - would i measure differences in the speed of light between different reflectors on the perimeter of the shell?
2 - if that's possible couldn't I measure my absolute velocity and determine the direction I'm travelling?

Ha! You are following the thinking of some great men. That is exactly what people thought. That is why the Michelson-Morley experiment, where they bounced light off reflectors in different directions, confused everyone by measuring the exact same time in all directions.

ThinkThrice said:
In the spirit of this forum I should first announce:
-generally, I have no idea what I'm talking about but look for you folks to enlighten me.

Question:
If I am traveling at a significant fraction of the speed of light and I wish to know my current absolute velocity can I use the speed of light in different directions?

If I'm moving at 50% the speed of light in some direction
and I build a spherical shell with reflectors facing the center of the shell
and I stand in the center of the shell and move with the shell with a stopwatch and shine a light at reflectors all around me in my shell
1 - would i measure differences in the speed of light between different reflectors on the perimeter of the shell?
2 - if that's possible couldn't I measure my absolute velocity and determine the direction I'm travelling?
I made an animation to illustrate what would happen in a scenario like you describe:

Now you will note that the light does not strike all the mirrors at the same time in the frame in which you are moving at 50%c but that is something that is outside your realm of measurement. If you could, then you would be able to measure your absolute velocity and determine the direction you are traveling.

If you want to see more animations developing conceptually the Michelson-Morley experiment that FactChecker mentioned, check out this thread:

Last edited by a moderator:

## 1. How do you calculate absolute velocity at 50% the speed of light?

The formula for calculating absolute velocity at 50% the speed of light is v = 0.5c, where v represents the velocity and c represents the speed of light (299,792,458 meters per second). This equation can be used to determine the absolute velocity of an object traveling at half the speed of light.

## 2. What units are used when calculating absolute velocity at 50% the speed of light?

The units used for calculating absolute velocity at 50% the speed of light are meters per second. This is the standard unit for measuring velocity and is commonly used in scientific calculations.

## 3. Can absolute velocity be greater than the speed of light?

No, according to Einstein's theory of relativity, the speed of light is the maximum speed at which all matter and information in the universe can travel. Therefore, absolute velocity cannot exceed the speed of light.

## 4. How does absolute velocity at 50% the speed of light compare to other velocities?

Absolute velocity at 50% the speed of light is considered to be a very high velocity. It is half the speed of light, which is approximately 149,896,229 meters per second. This is significantly faster than the velocities we experience in our everyday lives.

## 5. What are some practical applications of calculating absolute velocity at 50% the speed of light?

Calculating absolute velocity at 50% the speed of light is important in understanding the movement and behavior of objects in space. It is also crucial for developing and testing theories in physics, such as Einstein's theory of relativity. Additionally, this calculation can be used in engineering and technology, such as in the design of spacecraft and satellites.

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