Can We See Andromeda in Real-Time Using a Near-Light Speed Telescope?

[ppppppp]

hi, if i travels at 0.99999c, i will measure time between andromeda and I (events happens in andromeda) shrink to only 0.00447 x 2 millions yrs compared with a person in rest on earth?
Is this right, from t' = t x (1-v^2/c^2)^0.5

So if i travels to 0.99999999999999999999...c, then i can see things happen in andromeda just a few hours ago, because time dilation, i measure time between andromeda to me only a few hours different? (according to t' = t x (1-v^2/c^2)^0.5)

so if this is right, then we just need to make a nano telescope travel at 0.999999999...c (circling around Earth or whatever), we can see everything happens on andromeda almost in real time?

 

[Filip Larsen]

While correct in principle there probably are a few things you haven't thought about if you make a telescope that travels with speed 0.(9)c (with 20 nines) so that one hours of its proper time corresponds to one million year in the system at rest relative to Earth and Andromda:

For every hours it records another million year has passed on Earth. So even if the telescope was right next to Earth when it download its recordings, millions of years has passed on Earth. In fact, on Earth, the exact same events from Andromeda could have been recorded in that timespan.

Assuming the telescope is heading towards Andromeda it will, due to length contraction, travel from Earth to Andromeda in around 2 hours of its proper time. So if it recorded for 2 hours it would then find itself at Andromeda and a download from that position to Earth would (ignoring the impossible engineering task of this) take another 2 million year of Earth time, so Earth would have the recordings 2 millions years after the same events could have been recorded on Earth.

The energy required to accelerate even a very light nano telescope to that speed would be astronomical. The kinetic energy of an object at that speed is around 800 TJ/ng (Terra-Joule per nanogram).

In conclusion, it does not really make sense to make a relativistic telescope that uses time dilation to "see into the future" since that future sort of "stays with" the telescope so you cannot relay that information back to Earth and gain any advantage. You'd have to be on-board the telescope yourself for it to make a difference (and then the difference would only be for you and not the rest of the Earth).

 

[ppppppp]

i just realized this. Thanks! And I posted a new post Andromeda Paradox is flawed, next to this post

 

[ghwellsjr]

And then consider the fact that your nanotelescope would go whizzing past Andromeda in the next couple (of its) hours and now be very far away from Andromeda and even farther away from Earth so it would take even longer to download the info to Earth. So you'd want to have it stop, maybe orbit Andromeda (how do you orbit a galaxy?) and download the info as it received it. But wait, that's no different than us just looking at it through our Earth-based telescopes a few million years in the future, except that maybe we could see a little more detail of whatever stars it happens to be close to.

So you see that it not just a bad idea, it's a doubly bad idea.

 

[ppppppp]

ghwellsjr, it;s already solved in my reply Andromeda paradox is flawed! you are talking about engineering. We are not talking engineering feasibility! You will say the dame same thing to Einstein's twin paradox, same thing, blah blah, that no rocket can go near speed of light.>>>

 

[JesseM]

Did you see that I explained why your proposal wouldn't work on the [post=3260456]other thread[/post] where you asked the same question?