Relative Time: Earth vs Mars - A Physics Enthusiast's Question

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    Relative Time
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Discussion Overview

The discussion revolves around the concept of time dilation as it relates to the relative motion of Earth and Mars, particularly in the context of potential human travel to Mars. Participants explore the implications of different orbital speeds and gravitational effects on time experienced by individuals on Earth versus those on Mars.

Discussion Character

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

Main Points Raised

  • One participant questions whether the time experienced by people on Mars would diverge from that on Earth due to their different orbital speeds.
  • Another participant notes that while there is a time dilation effect from the motion of planets and gravitational influences, the velocities involved are small compared to the speed of light, resulting in minimal effects.
  • It is suggested that the time dilation would be very slight and overshadowed by communication delays and other factors related to travel between Earth and Mars.
  • A calculation is presented indicating that for an object traveling at 10,000 m/s relative to Earth, the time dilation would amount to approximately 1.5 seconds per century.
  • Some participants mention that while time dilation is measurable with modern precise clocks, it is not significant on a human scale, such as for personal events like birthdays.
  • There is a reference to GPS satellites accounting for time dilation effects, both from speed and gravitational influences, although specific velocities are not detailed.

Areas of Agreement / Disagreement

Participants generally agree that time dilation exists but express differing views on its significance and practical implications. The discussion remains unresolved regarding the extent to which time would diverge for individuals on Mars compared to those on Earth.

Contextual Notes

Some calculations and assumptions regarding velocities and their effects on time dilation are presented, but the discussion does not resolve the complexities involved in these calculations or their practical applications.

Wh17e
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Hi, everyone.

I'm new here so I'll introduce myself: I'm not a physicist, just a physics enthusiast. Although I have studied some physics at school and college, I've never been taught relativity, which I've kind of learned about on my own.

My question might seem stupid to you, and I apologise if it is, but I've been thinking about this for some time now, and I can't get to the bottom of it. Here's the thing:
The Earth moves at its own orbital speed around the Sun, and so do the other planets in this system. But as they have different distances to the sun, they travel at different speeds. Those speeds relative to the speed at which Earth is moving, I reckon they are pretty big.
So, if we ever were to send people to Mars, would their time grow further and further apart from ours every year?

I apologise in advance for the weird English (I'm not native), and thanks for any answers you might give me.
 
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A priori, there is a time dilation effect due to the moving of the planets as well as due to the gravitational time dilation. However, the velocities are actually pretty small compared to the speed of light so the effect is very small. The orbit velocity of Mercury (which is the fastest) is about 0.0001c.
 
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Very, very slightly, yes. But the difference would be overshadowed by the complications of communicating over such a distance and the time differences caused by speeds going to and from Mars, anyway. The difference would probably be un-noticeable.
 
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Orodruin said:
A priori, there is a time dilation effect due to the moving of the planets as well as due to the gravitational time dilation. However, the velocities are actually pretty small compared to the speed of light so the effect is very small. The orbit velocity of Mercury (which is the fastest) is about 0.0001c.
... and relativistic corrections go as ## \sqrt(1-v^2/c^2) ##, which for ## v=0.0001c ## yields a correction of 0.0000005%.
 
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That amount of time dilation is definitely measurable with modern precise clocks, but not noticeable on a "human" scale. I.e. you couldn't use time dilation to pretend that you remembered your brother's birthday and claim that it is just relativity's fault.
 
DaleSpam said:
you couldn't use time dilation to pretend that you remembered your brother's birthday and claim that it is just relativity's fault.
What? Now I'm in trouble!

Otherwise, with precision clocks if I'm not mistaken GPS sattelites do take into account time dilation, both from speed and gravitational - there might be a thread about this somewhere in the forum. Not sure what their velocity is, though.
 
Wh17e said:
Hi, everyone.
Those speeds relative to the speed at which Earth is moving, I reckon they are pretty big.
So, if we ever were to send people to Mars, would their time grow further and further apart from ours every year?

A very rough calculation. For something traveling at 10,000 m/s relative to Earth, the time dilation would be about 1.5s per century.
 
wabbit said:
What? Now I'm in trouble!

Otherwise, with precision clocks if I'm not mistaken GPS sattelites do take into account time dilation, both from speed and gravitational - there might be a thread about this somewhere in the forum. Not sure what their velocity is, though.
Yes it is noticeable with precision clocks. No it is not noticible with birthday cards.
 
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