Hypothetical thought experiment about time dilation

In summary, if you are able to hit the speed of light, that means time has been "bypassed" for those on Earth.
  • #1
awalltep81
3
0
Let's say that you leave Earth at 75% the speed of light (c). You travel out and back for a minute. And when you come back an hour has passed on Earth. (I understand this is not accurate; I'm just using it for the sake of this hypothetical) You leave again at 99% of c, again for a minute. When you get back to Earth, a day has passed. You do it again at 99.99999% of c. You come back to Earth and 10 years has passed. Again at 99.99999999999% and 10,000 years has passed. You can keep adding 9 onto the end of that percentage, and the one minute you travel will be more and more time for those left behind.

Isn't it true, then, if you are actually able to hit the speed of light, that means upon "returning" you've completely bypassed time itself? Shouldn't an infinite amount of time have passed? Since you can "bypass" (can't think of a better word) any measurable amount of time by getting closer and closer to c, wouldn't it make sense that to actually hit c would be to "bypass" an immeasurable amount of time?
 
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  • #2
awalltep81 said:
Isn't it true, then, if you are actually able to hit the speed of light,

It turns out you will not be able to accelerate to the speed of light relative to the Earth. The more energy you expend from your engine, the faster you will get, up toward - but not including - the speed of light.
 
  • #3
1977ub said:
It turns out you will not be able to accelerate to the speed of light relative to the Earth. The more energy you expend from your engine, the faster you will get, up toward - but not including - the speed of light.

I know you can not actually reach the speed of light. It's kind of a "what if"?
 
  • #4
Yes, relativity says it is impossible for any "massive" object to move at the speed of light. So even in a "thought experiment" you cannot say "if you are actually able to hit the speed of light". You are essentially asking "if relativity were wrong, what would relativity say about this situation?"
 
  • #5
awalltep81 said:
Isn't it true, then, if you are actually able to hit the speed of light, that means upon "returning" you've completely bypassed time itself? Shouldn't an infinite amount of time have passed?

The faster you go, the slower your clock ticks relative to Earth. For "an infinite amount of time" to pass, you would have to travel while ∞ time passed on Earth. Presumably the Earth will not last that long. There might be a big crunch.
awalltep81 said:
Since you can "bypass" (can't think of a better word) any measurable amount of time by getting closer and closer to c, wouldn't it make sense that to actually hit c would be to "bypass" an immeasurable amount of time?

[edited to turn it around]
The larger and larger you make x, the smaller and smaller 1/x becomes. Doesn't it make sense that for x to "actually hit" infinity, then 1/x would be zero? Anyhow, no mass can ever be accelerated to the speed to light.
 
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  • #6
HallsofIvy said:
Yes, relativity says it is impossible for any "massive" object to move at the speed of light. So even in a "thought experiment" you cannot say "if you are actually able to hit the speed of light". You are essentially asking "if relativity were wrong, what would relativity say about this situation?"

Ok. I never realize that flaw in the hypo. Thanks.
 
  • #7
awalltep81 said:
Let's say that you leave Earth at 75% the speed of light (c). You travel out and back for a minute. And when you come back an hour has passed on Earth. (I understand this is not accurate; I'm just using it for the sake of this hypothetical) You leave again at 99% of c, again for a minute. When you get back to Earth, a day has passed. You do it again at 99.99999% of c. You come back to Earth and 10 years has passed. Again at 99.99999999999% and 10,000 years has passed. You can keep adding 9 onto the end of that percentage, and the one minute you travel will be more and more time for those left behind.

Isn't it true, then, if you are actually able to hit the speed of light, that means upon "returning" you've completely bypassed time itself? Shouldn't an infinite amount of time have passed? Since you can "bypass" (can't think of a better word) any measurable amount of time by getting closer and closer to c, wouldn't it make sense that to actually hit c would be to "bypass" an immeasurable amount of time?
Just for the fun of it, I'm going to modify your question to bring it in line with reality. I realize you were not concerned with the details so I'm not faulting you on this point.

If we start with a speed of 99% of c, the time that will pass on Earth will be 7.088812 minutes. If, instead of adding a single 9 onto the end of the percentage, we add a pair of nines, the time will go up by about a factor of 10. So at 99.99%c, 70.712446 minutes will transpire on Earth. At 99.9999%c, it is 707.106958 minutes on Earth. We can see a pattern here and if we realize that the factor approaches the square root of one-half (0.70710678118654752440084436210485) times a power of ten, then we can easily predict what the factor is for speeds as close to the speed of light that we desire. But no matter how many pairs of nines we want to add onto the end of the percentage, the digits in the factor will always approach that of the square root of one-half. So, for example, with 30 pairs of nines in the percentage of the speed of light, the factor will be 707106781186547524400844362104.85 minutes. Now that is a very long time, much longer than the age of the universe but still no where near infinity.
 

1. What is a hypothetical thought experiment about time dilation?

A hypothetical thought experiment about time dilation is a theoretical scenario often used in physics to explore the concept of time dilation, which is the phenomenon where time passes at different rates for objects moving at different speeds. It involves creating a hypothetical scenario and examining how time would behave in that situation.

2. How is time dilation related to the theory of relativity?

Time dilation is a key principle of the theory of relativity, which states that time and space are relative to the observer and can be affected by the speed and gravity of objects. The theory of relativity explains how time dilation occurs and how it impacts the passage of time for objects in motion.

3. Can time dilation be observed in everyday life?

Yes, time dilation can be observed in everyday life, although the effects are very small at typical speeds. GPS satellites, for example, have to account for time dilation in order to accurately measure time and calculate location. Additionally, astronauts in space experience time dilation due to their high speeds.

4. How does time dilation affect the aging process?

As an object moves at high speeds, time passes slower for that object, meaning it ages slower compared to a stationary observer. This effect becomes more noticeable as speeds approach the speed of light. However, the difference in aging is only significant for objects traveling at extremely high speeds or in a strong gravitational field.

5. Can time dilation be reversed or manipulated?

While time dilation is a natural and inevitable consequence of the theory of relativity, it can be reversed or manipulated in certain scenarios. For example, time dilation can be reversed by slowing down or stopping the movement of an object. Additionally, the effects of time dilation can be manipulated through the use of extremely strong gravitational fields.

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