Say we send a probe to Alpha Centauri today, 1/11/18. It travels at near the speed of light. When it arrives, it takes photos and beams them back to us, which takes 4.5 years or so.
But, the probe traveled at, let's say, 0.9999999C over the whole journey. So it experienced time dilation such that its clock appears to be running about one twentieth the speed of clocks on Earth.
Which of these is true? A) The journey only appeared to take about 3 months from the probe's frame of reference, but 4.5 years from Earths frame of reference, or B) The journey appeared to take 90 years from Earth's frame of reference, but only 4.5 years from the probe's frame of reference?
In other words, when do those images arrive back here on Earth? Related question, if the probe puts a timestamp on the photos, what does the timestamp say?
Joshua Johnson
Time dilation is a brainlet philosophy unsupported by actual science
Owen Adams
at a speed of 0.9999999C, it would actually run at a 2000th the speed, so it would tactualy take around 17 hours from the probe's perspective but 4.5 years from Earth's perspective.
>he doesn't know about time dilation in cosmic rays and particle accelerators
Owen Lopez
Think about what you just typed and how it doesn't make sense.
Aaron Bailey
wait fuck, i might have gotten that the wrong way round... yeah, it's the other way around. the time you put into the equation is how long the journey would be from the object's frame of reference, and the number you get out is the time someone at a frame of reference technically travelling at 0.9999999C away from you would see...
so 4.5 years for the probe, 10,062 years for earth
Isaiah Cooper
it doesn't make much sense to begin with, I see where i fucked up though
Carson Hill
Oh, oops. In the OP I used a dumb online calculator thing... It gave me a value of 0.45, but that's actually a percentage, so yeah, on two-thousandth, not one twentieth. Still, you're saying that the answer is B?
So we wouldn't get the pictures back here on Earth for 10000 years?
Aiden Garcia
yeah, the answer is B because from the probe's perspective nothing changes, it still has to travel at 0.9999999C for the distance it originally needed to go. Specifically, it would take 10,066.8 years, assumming 4.5 light-year distance is correct.
with [math]t_0[/math] being the time for the probe, in any measurement unit you fancy, and [math]t[/math] being the time for the observer. you can replace [math]\frac{v^2}{c^2}[/math]
Thomas Price
fugg you can replace that with a speed relative to the value of the speed of light, squared, like 0.99999^2, if you already know it.
Jackson Campbell
So we could actually get the pictures back sooner if we sent the probe at a slower velocity.
If we sent it at 0.5C, for example, it would only take about 9 years to get there from the probe's perspective and about 10 years from ours.
