Is it possible to look into the past, using mirrors?

[Alyx Vance]

But actually getting that mirror to a position one light year away will take waaaaaaaaaaaaay longer than that

Also, since both the mirror and earth would be moving during the entire journey, I think there's probably some special relativity stuff going on here that would make it a bit off from two years

Then you have to get it to aim perfectly

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[Headcrab Zombie]

Then you have to get it to aim perfectly

I'm not talking about aiming
I'm talking about time
I'm trying to find the video I found earlier explaining it because it was really simple

[Alyx Vance]

I'm not talking about aiming
I'm talking about time
I'm trying to find the video I found earlier explaining it because it was really simple

I know, I was just adding on another point

[Ipquarx]

I know, I was just adding on another point

Adding on another point, the mirror would have to be damn near perfectly flat (like literally tens of thousands of times flatter than your average storebought mirror is), at half a light year an error of anything more than 1 nanometer will cause light reflected off it to miss earth completely.

[Headcrab Zombie]

Alright here's what I'm trying to say. It's really basic math but something a lot of you are missing



So you guys are thinking of the earth and the mirror like the two objects in the left. A photon is emitted from a (in your mind) unmoving earth, travels straight to the mirror, and straight back to the earth, which are one light year away, for a total round trip of two light years.
But what actually happens is the earth and mirror are moving, so it looks more like the one on the right. The actual distance, in lightyears, is solved by the Pythagorean theorem, a² + b² = c², where  c is the total distance traveled by the photon, and a and b are the distances between the mirror and earth, and the distances between the earth/mirror before and after the photon reaches it


Since the speed of the earth and sun are slow compared to light speed, I'm pretty much just nitpicking, but I felt I should make the point


Of course it may change depending on what point of reference you're looking at it from. forget my understanding of relativity

[KickFlow]

We understand what you're saying. It's cool but that isn't concerning.
We'd also need a perfect telescope that'll look straight from the earth to the mirror the exact degrees to see us in the reflection.

[Oasis]

I like how the entire topic is focusing on putting a mirror in space so we can see ourselves 2 years in the past. Brilliant thinking people, I smell a nobel prize.

[Couatl]

wouldn't the mirror be blocked by the sun

[Blockaium]

brian = ded

[Blockaium]

wait a minute, sorry for doublepost but wouldnt there need to be light on the mirrors to see anything on it? so in that case wouldnt the light be so intense it can vaporize things? i mean if they have giant mirrors at the solar field in nevada which have been shown to vaporize birds, wouldnt this possible kill an entire planet?

[-Setro-]

it'd take 4 years for the light to travel to the mirror, then back to the telescope
i think?

[YouDontKnowMe]

I TRIED IT AND THIS HAPPENED

I used to be a moon.
Not just any moon.
Batmoon.

[Nonnel]

it'd take 4 years for the light to travel to the mirror, then back to the telescope
i think?

No, two years is already the added up time. It's a light year away.

[KickFlow]

it'd take 4 years for the light to travel to the mirror, then back to the telescope
i think?

https://www.youtube.com/watch?v=EYjiIsENvcc&t=4m27s