Does time dilation only affect matter that has mass?

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Discussion Overview

The discussion revolves around the concept of time dilation, particularly whether it affects only matter with mass. Participants explore scenarios involving a spaceship traveling at relativistic speeds and the implications of time dilation on the perception of time from different frames of reference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions how time dilation affects the perception of time for a spaceship traveling at 99.99% of the speed of light, noting a discrepancy in the arrival times of a radio wave and the spaceship itself.
  • Another participant corrects the initial claim about time dilation, stating that the spaceship arrives just over 1 year later according to Earth's clocks, while only experiencing a fraction of that time (1/70 year) from its own perspective.
  • A subsequent reply acknowledges the correction and expresses confusion about the implications of time dilation, suggesting that if the spaceship could travel at an even higher speed, the travel time from its perspective would be significantly reduced, potentially leading to a perception of instantaneous travel.
  • One participant speculates about the implications of light's perspective, proposing that light from the Big Bang could be perceived as having spread out instantaneously across the universe.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of time dilation, with some expressing confusion and others providing corrections. Multiple competing views regarding the effects of speed on time perception remain evident.

Contextual Notes

There are unresolved assumptions regarding the nature of time dilation and its effects on massless particles versus massive objects. The discussion also touches on the conceptual challenges of understanding relativistic speeds and their implications for time perception.

Milfeulle
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Does time dilation only affect matter that has mass?

For example, A spaceship is 1 light year away from Earth at rest. It sent out a radio wave to Earth then travels at 99.99% of the speed of light. On Earth, from our perspective, we will receive that radio wave 1 year later but the spaceship arrives 70 years later. If that spaceship speed up to 99.999999% of the speed of light, it will take 7000 years from our perspective to see that spaceship.
As a result, from our perspective, the faster that ship travels, the later it arrives, how does that makes sense?
 
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Milfeulle said:
A spaceship is 1 light year away from Earth at rest. It sent out a radio wave to Earth then travels at 99.99% of the speed of light. On Earth, from our perspective, we will receive that radio wave 1 year later but the spaceship arrives 70 years later.
You have the dilation the wrong way round. The spaceship arrives just over 1 year later by Earth's clocks, but 1/70 year later by the ship's own clocks.
 
Ahh I see, I got the wrong way around all this time! Thanks for the reply!
 
DrGreg said:
You have the dilation the wrong way round. The spaceship arrives just over 1 year later by Earth's clocks, but 1/70 year later by the ship's own clocks.

So that means it only took the ship 5.21 days to arrive on Earth (from the spaceship's perspective) ? If so, that means if the spaceship can travel at 99.9999999999999% of the speed of light, it will only takes 1.41 second to arrive on Earth from the spaceship's perspective. It would be almost like... instantaneous travel...?
In another word, From the light's perspective, all that light from the Big Bang 14 billion years ago was already spread out everywhere in the Universe since the beginning and what we're seeing are just the trails it left behind?
 
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