Relative Time in Space: What Speed for 1 Day Equals 1 Day on Earth?

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Discussion Overview

The discussion revolves around the concept of relative time experienced by a ship traveling through space compared to time on Earth. Participants explore the implications of speed on time dilation, particularly in the context of special relativity, and whether there exists a speed at which time would be perceived as equal for both the ship and observers on Earth.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that any speed will result in both observers seeing the other's clock running slow.
  • Others argue that if the ship and Earth are moving relative to each other, there is no invariant way to match their "rates of time flow," making the question ill-defined.
  • A participant suggests specific speeds (11 km/s in the nearby Solar System, up to 500 km/s outside the Solar System) but is questioned about the basis for these numbers.
  • Another participant mentions that traveling at 87% the speed of light results in 1 day on the ship equating to 2 days on Earth, and seeks a lesser speed for equal time perception.
  • It is noted that relative speed zero (the ship not moving relative to Earth) would result in equal time perception.
  • One participant references the time dilation formula as a method to calculate the relationship between speed and time experienced by observers.

Areas of Agreement / Disagreement

Participants express differing views on the nature of time dilation and the conditions under which time can be perceived as equal. There is no consensus on a specific speed that would achieve this equality, and the discussion remains unresolved.

Contextual Notes

Limitations include the dependence on definitions of time and speed, as well as the unresolved mathematical steps related to time dilation calculations.

mileymo
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What speed does a ship traveling through deep space need to travel at for 1 day on the ship to equal 1 day on earth?
 
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Any speed will do. But both will observe the other guy's clock is running slow !
 
I think it's 11km/s in the nearby Solar system, up to some 500km/s outside the Solar system, and even bit faster outside the Milky Way.
 
mileymo said:
What speed does a ship traveling through deep space need to travel at for 1 day on the ship to equal 1 day on earth?
If by 1 day you mean 24 hours measured by a clock on Earth and 24 hours measured by a clock on the ship, then they represent the same amount of time regardless of the speed of the ship relative to Earth. During the 24h measured by a clock on Earth a person on Earth would have aged 1 day, during the 24h measured by a clock on the ship a person on the ship would also have aged 1 day.
 
mileymo said:
What speed does a ship traveling through deep space need to travel at for 1 day on the ship to equal 1 day on earth?

If the ship and the Earth are moving relative to each other, then there is no invariant way of matching up their "rates of time flow". So this question doesn't have a well-defined answer.
 
SlowThinker said:
I think it's 11km/s in the nearby Solar system, up to some 500km/s outside the Solar system, and even bit faster outside the Milky Way.

How are you coming up with these numbers?
 
What I mean is, if you travel at 87% the speed of light, then 1 day on that ship is equal to 2 days on earth. So, is there a lesser percentage of the speed of light at which time would be equal for both the ship and the people on earth?
 
mileymo said:
What I mean is, if you travel at 87% the speed of light, then 1 day on that ship is equal to 2 days on earth.
That's only for an observer on Earth ! The guy in the ship thinks it's the other way around !

So, is there a lesser percentage of the speed of light at which time would be equal for both the ship and the people on earth?
In your line of reasoning: zero. Stay put on earth.
 
Thanks. Much appreciated!
 
  • #10
So, is there a lesser percentage of the speed of light at which time would be equal for both the ship and the people on earth?
There is - relative speed zero, meaning that the ship is not moving relative to the earth.
You can calculate this from the time dilation formula, which google will find pretty quickly - try "relativity time dilation".
 

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