Point of Reference and Speed of Light: A Thought Experiment

In summary, the conversation revolves around a thought experiment involving the speed of light and points of reference. An astronaut is launched into orbit at near the speed of light and returns after 500 years from the scientist's point of reference, but only 60 seconds have passed for the astronaut. The scientist plans to launch space trash to hit the spaceship, but the question is whether it will actually hit the spaceship or not. The conversation also delves into the concept of points of reference and how they affect time and space.
  • #1
SpeedSpaceman
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I have a question (thought experiment) that pertains to the speed of light and point of reference. I'm just interested in thinking about this subject and I can't quite get my head around this. I'm sure the answer is probably simple. Thank you for your help. By the way, if the answer involves math at all it will be lost on me.

An Astronaut and a Scientist agree to conduct an experiment. The Astronaut will be launched into an agreed upon orbit (Orbit X) around the Earth in a spaceship traveling near the speed of light. The duration of his flight, from his point of reference will only last sixty seconds. However, from the point of reference of the Scientist on Earth, the Astronaut will not decelerate and return to Earth for 500 years.

Now, the Astronaut and the Scientist agree that a "day" after the Astronaut leaves on his trip (a "day" after in the point of reference for the Scientist) the Scientist will begin to launch massive amounts of space trash into Orbit X, and that his predecessors will do the same for 500 years. They will try to “hit” the spaceship.

So, the Astronaut has the course laid out, accelerates for sixty seconds and then decelerates, returns to Earth and it is 500 years later. Or does he? Does he manage to make his 60 second/500 year voyage safely? Or did the space trash the Scientist threw into orbit hit him? If it did hit him, did he crash and eject to Earth in 20 seconds, 33 seconds and then land on Earth 200 years or 300 years later?

I guess the point I am trying to wrap my head around is that I always hear about points of reference in relation to the speed of light and time travel. However, “where” does the point of reference begin and end? Does the material making up the spaceship only endure 60 seconds of physical strain since it is accelerated at tremendous speeds? Okay, if so, the space debris, space trash and asteroids, etc that are crisscrossing our Astronauts path are not moving this quickly, and there are 500 years worth moving around that orbit, the same orbit in space as the Astronaut, but why does it not hit him? Is the problem that I should be thinking of two discreet “spaces” as well as two “times”?


Note: All numbers and times are just arbitrary. I don't know exactly what speed or what time this would all work out to. I understand that we can't build a ship like this. I often hear this same type of scenario in physics shows meant for a general audience, but they don't really explain what happens "during" the time periods for each person, and how space interacts and functions.
 
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  • #2


hi, speedspaceman. Welcome to physicsforums :)
If they launched the space trash in the right speed and direction so it collides with the spaceship, then it will hit the spaceship. In the reference frame of the earth, the space trash is fired after one day. And in the spaceship's reference, the trash is fired after some different time interval. There is no problem with this because the two reference frames will measure time intervals and spatial lengths differently.
 
  • #3


Speedspaceman, the simple answer to your question is that if the Astronaut hits a piece of debris after say 30 seconds of his time, then it will be after 250 years of Earth time. Is that all you are concerned with?
 

FAQ: Point of Reference and Speed of Light: A Thought Experiment

1. What is the concept of a point of reference in relation to the speed of light?

The point of reference is the frame of reference from which the speed of light is measured. It can be any stationary object or observer that is used as a reference point to determine the speed of light.

2. Can the speed of light be affected by the point of reference?

No, the speed of light is constant and independent of the point of reference. This is one of the fundamental principles of Einstein's theory of relativity.

3. How does the speed of light change when measured from different points of reference?

The speed of light remains constant at approximately 299,792,458 meters per second regardless of the point of reference. However, the perceived speed of light may vary depending on the relative motion between the observer and the source of light.

4. Can a thought experiment accurately demonstrate the speed of light and its relation to the point of reference?

Yes, a thought experiment can provide a theoretical understanding of the concepts of the speed of light and point of reference. It allows for exploration and analysis of these concepts without the limitations of physical experiments.

5. How does the point of reference affect our perception of time in relation to the speed of light?

The point of reference can affect our perception of time due to time dilation, a phenomenon in which time appears to pass slower for an observer in motion relative to another observer. This is another key principle in Einstein's theory of relativity.

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