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

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SUMMARY

The discussion centers on the concept of time dilation as described by Einstein's theory of relativity, specifically addressing the speeds required for a ship traveling in space to experience time equivalently to Earth. It is established that at speeds of 11 km/s in the Solar System and up to 500 km/s outside it, time dilation effects become noticeable, but both observers will perceive the other's clock as running slow. The time dilation formula can be used to calculate the exact speed needed for time to be perceived equally, with a speed of 87% of the speed of light resulting in a 2:1 time difference. For equal time passage, the relative speed must be zero, meaning no movement between the ship and Earth.

PREREQUISITES
  • Understanding of Einstein's theory of relativity
  • Familiarity with time dilation concepts
  • Basic knowledge of the speed of light (approximately 299,792 km/s)
  • Ability to use the time dilation formula
NEXT STEPS
  • Research the time dilation formula in detail
  • Explore the implications of traveling at relativistic speeds
  • Learn about the effects of gravity on time as described by general relativity
  • Investigate practical applications of relativity in modern technology, such as GPS systems
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Physicists, students of physics, and anyone interested in the implications of relativity on time perception and space travel.

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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