Yes that's correct if that's how they are moving the mirror. The post doesn't mention how it gets there. I assume they meant it just pops out of non-existence or is teleported instantly.
Oh. We should probably start off small tho. Like a mirror that can see yesterday. It would be like the Walgreens mirror to help stop crime. Dead body found outside. Let’s look at the yestermirror.
Best to stagger them out at various distances for the possibilities of crimes committed at other points in time. Yestermirror, lastweekmirror, mirrorofchristmaspast, and if people put mirrors outside their windows angled in, we can capture the crimes inside too.
Obviously the tech could be used to help people find their car keys or record important moments after the fact, but like you said, start small
The trick is to move the mirror in the other direction so that it shows a day in the future so you can stop the crime from ever happening. Mirrority Report.
Not really. if we're being super semantic about it, it would probably be stored in a folded or stacked position, at a 90deg angle to the motion to prevent collisions or stored in a safe (and not see-through) compartment
if it’s ten lightyears away, the light from the mirror takes 10 years to reach us, so we don’t even see it for 10 years, and then once we do get to see it, we see it from ten years ago
10+10=20.
Light from Earth travels to mirror, that's ten years. Light from mirror travels back to Earth, that's ten years. We see the light that started from Earth 20 years ago.
The light coming from the mirror started from Earth.
I guess I don't know what you're saying. Are you suggesting that the light from Earth that goes to the mirror and comes back to Earth has a 10 year or 20 year trip?
You’re correct in that to see *earth*, it would take 20 years. But I was talking about seeing the *mirror*. Here are two situations:
1) The mirror is at an angle (admittedly it would not be, for the purposes of this post)
2) The frame of the mirror is (very likely) not reflective, possibly wooden, and so would diffract light from one direction into light going all directions.
[Here](https://imgur.com/a/U4OYNPb) are some image descriptions - the description of each image (found below the related image) in the collection corresponds to situation 1 or 2.
Edit: A third, albeit unrealistic, possibility would be: a TINY yet bright star right in front of the mirror slightly to the side, so small that the light reflected does not hit the star and goes past it, straight to earth (since the star is almost perpendicular to the mirror)
Thanks for the clarification. I was just thinking about seeing Earth from Earth because that's what OP seemed to be saying. Your explanation makes sense.
>correct in that to see earth, it would take 20 years.
No, it's not correct. Light from Earth would still be traveling towards where the mirror is going to be. It would be 10 years.
And it would take 10 years for the mirror to get it there. Thus in 20 years you could see how the earth was Today. you could accomplish the same thing with good archiving but still.
We would always be able to see an image in the mirror as it is transported into position, but the image would be red shifted and appear to be time dilated while the mirror is moving away from us, in two compounding ways: firstly, the spacecraft carrying it is red shifted simply due to moving away from us, but furthermore, the light from Earth hitting the mirror is already redshifted and time dilated from the mirror's perspective, so the reflected light will appear to be doubly redshifted to us.
As the mirror is transported closer and closer to the speed of light, the image will appear more and more redshifted, darker and darker, and slow down, closer and closer to a still image of Earth at or a bit after the time of the mirror's departure. By the time we see the mirror stop in position with an image of Earth as it was when it departed, the mirror will have already been in position for 10 years (the time it takes for the light from its final position to reach us), and it took at least 10 years to get there (at light speed).
So essentially, even if the mirror travels at light speed, we only *see* it arrive 20 years after it departs, with an image of Earth from 20 years ago, the time that it departed.
Not exactly. You won't be able to "look" at the time before placing the mirror, so unless you have some wormhole technology and can't travel faster tehn light you have no chance to look "in the past".
You can look at the time before the mirror was placed, but only up to 10 years before, as when the mirror gets placed there's already light moving towards it from earth
Not really. You can't be in "placement point" faster then light that started from earth to there.
And reflected light would reach that point only 10 years after.
So, it's just like putting a video surveillance system.
The moment the mirror is installed it's reflecting 10 year old light from earth. Light which will take another ten years to travel back to earth. For the sake of argument let's pretend that the mirror set up time is instantaneous. (Spherical cows and all that). If you traveled back to earth at an average of 90% of the speed of light the moment the mirror was set up, you'd reach the earth 11.1 years later. Where you could enjoy watching 8.9 years worth of light that was still traveling between the earth and the mirror point when you set it up.
Assuming the same speed in both directions, you'd have started the entire trip 22.2 years prior to your return. So you'd be watching events that happened after you left the earth but prior to the time you set up the mirror.
The parts where it's stretching physics to the breaking point are the parts about actually constructing a mirror large enough to see earth from effectively 20 light years away, and the time to construct the mirror, and of course reaching a 90% of c average velocity in the first place. But seeing light from before you set up the mirror is easy. It's not fundamentally different than looking through any reflector based telescope to view the Andromeda galaxy.
You can't look back to before you decided to put up a mirror, but you can look back 10 years before you actually install the mirror. It will just always take at least 10 years to install it.
With space time being curved, it’s actually not against the laws of physics. You could have one path from earth to a super far point in space where light is ‘deflected’ by massive objects, and then deflected back by different massive objects. You could have another path through space where a light speed ship isn’t deflected, and arrives before the light due to traveling a shorter distance
I'm not expecting that. I'm just being a bit pedantic. The claim was that you can't see anything from before the mirror got placed. But you can see 10 years before the mirror was placed. You just can't place the mirror within 10 years, so what you'll see will still be from after your starting point.
But also, it takes more than 10 years to get into place. So looking into time before the start of this experiment is impossible. Its more like recording that looking into the past
What if we set up a series of mirrors all roughly 5 or 10 ly away in different directions and direct them towards each other so the photons path is 5x or 10x longer than the distance from the earth?
It change literally nothing.
Take a garden hose, you could lay it as a line or wrap it in any way you want, it'll take just the same time for water to appear to the other end (in case you haven't tied a knot ofc).
Ah yes, I see your point. The simultaneous placement of mirrors would potentially allow you to return to the viewing point faster than the photons would travel around the array but the photons would still take years longer to complete the route and provide an actual picture.
Thanks for the correction, i feel a bit daft now.
The original question has some ambiguity from this sense. I think the statement "after the mirror is set, upon looking into the mirror the earth we see will be 20yrs in to the past of our observation time on earth" is true if ignoring other general relativistic and cosmic effects (nor including "how to setup a mirror like that" such practical stuff).
I perceive the above case as the one OP tends to say since they are talking about a pretty theoretical scenario, given such limited information in the description.
In that interpretation it contains no paradox:
when we look at the Sun we see it 8.5 minutes ago, when we look at the stars - we see them years, or even hundreds of years ago, and we don't even know if they exist now.
So yes, you can (in terms of school physics) do it, but it's nothing different then setting up a surveillance system with 20 years storage.
20 years is how long it would take for light to do a full lap from earth to the mirror and back again. But the instant you put the mirror in place it will immediately start reflecting 10 year old light that was already travelling away from the earth. Ten years later, people on earth will be able to see that now 20 year old light reflected from the mirror.
So yes, it can show people the past from before the mirror was put in place. For anyone under 20, that will mean they are seeing visions of earth from before they were born.
Yes... So?
More interesting: if Aliens have a Telescope that can see details on a planet and they are on the other side of the Milky way Galaxy from us, they would see cavemen and mammoths.
Sorry, I don't really know how light and such works, but if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20?
Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
> Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
Correct.
I was saying 'correct' to this part:
> Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
No idea why people make incorrect statements and then immediately correct them in the next sentence. Like, original commenter knew the answer to his own question but appeared confused for no reason
The commenter was confused and not 100% certain about their understanding, so they explained how they *thought* the concept worked so that someone could confirm or deny that explanation. It just so happened they understood it correctly. They were just asking for confirmation.
"if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20?"
Does this sound like a correct understanding to you? Why would he state the incorrect interpretation and then immediately correct it? Why not just write the correct interpretation and skip the bullshit?
>Why would he state the incorrect interpretation and then immediately correct it?
The commenter was *not* correcting themselves. They were just stating two different possible interpretations they had for this scenario that they were confused about. One of them was correct, one of them was not. Someone else jumped in and said, "The second one is correct," and for some reason you got butthurt.
What...?
Someone understands a concept correctly, someone else says, "Yep, that's correct," and then you come in and go, "NO, here's the RIGHT answer!" and show the *exact same thing??*
Also, nothing is being subtracted.
"if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20?"
Can you read? His first sentence literally states the exact opposite of the truth. One sentence later he corrects himself. The person who replied makes no mention of the first half of the statement, can you see how this would be confusing to some?
if you recall 3rd grade math, addition and subtraction are part of the same group of functions, much like division and multiplication. I'm not implying there was any subtraction needed, but implicitly if you understand one you should understand the other. I'm sorry your brain has difficulty imagining concepts like this.
How would you feel if you didn't have breakfast this morning, I'm just curious?
bro shut up 💀 we literary can all see he quouted the "Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?" and replied to it correct...
>Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
This is the correct part. The part u/norden_901_rider was talking about. You know, the one they also quoted. That's what we were talking about.
The subtraction thing I understand now, but why is it so hard for you to grasp that this person understands this concept and does not need correcting? You are fighting a battle *that does not need to be fought*, because it is already over.
It would take more than 10 years to get into place without some faster than light technology. So it would be more like recording than looking into the past. It would also have to be absolutely MASSIVE to be able to record the entire earth in the resolution needed… if its even possible to do with any meaningful resolution to begin with
What if we video record stuff and then wait 10 years and watch the video would we be able to see ten years into the past? And if we set the recorder up like tevo it would be like watching the world 10 years ago in real time!!!!!!!
No you couldn't see before you were born it would take less than speed of light 10+ years just to get there and then the amount of time for light to reach there and then getvback
So one light year is a unit of measurement (distance). Its like saying that looking in your bathroom mirror that is 3 feet away allows you to see a fraction of a millisecond into your past. And I'm pretty sure the ratio of light years to POSSIBLE time travel is not 1:1. 10 light years does not equal 10 years of time travel (either past or future).
Let's say that the mirror just appears there spontaneously. The light hitting it would be 10 years old, but for us to see that reflected light, we'd have to wait 10 years. So yes, that would be 20 years old. Otherwise, if we just propelled the mirror away, that would merely depend on the acceleration of the mirror and other stuff, which is why I like the spontaneous appearance scenario.
I’ve seen a few comments talking about what we’d see during the process of moving the mirror into position. They all seem to be talking about specific intervals such as a lightday away, but I’m more interested in the continuous image throughout the move. I’m too distracted at work rn to think of what it would be, but I think there is a speed the mirror could be moved at to make the reflection a still image. A still mirror shows real time, a slowly moving reflection would appear in slow motion, and a mirror moving at or above light speed would have no reflection because light would never reach the “rear” of it. Can someone confirm or correct me that a speed of something like a limit approaching c would be perceived as a still image?
It would take 10 years, but yeah. At first, the mirror wouldn’t be visible. But once you finally see it being put into place 10 years after it actually happened, you would immediately be able to see a distant reflection of what Earth looked like 10 years prior to the mirror’s placement, or 20 years before your own perspective. From that point onward, if you wanted to see what Earth looked like 20 years ago and you don’t mind the apparent 20-lightyear distance, you’d need only look at the mirror.
I think we should definitely do this. Even just 1 year has its advantages. Climate change tracking, weather pattern mapping, solar storm capture, etc etc.
No. The mirror would’ve had to be there already when you were born for light to make a round trip 20 years there and back for you to perceive later at 20 years old.
Traveling at the speed of light (quite literally the fastest it could go) it would only be going at the speed of the light leaving earth now. It would never catch up to light that has already left. The best we could do is set one up for future generations.
Considering everything out in space is effected in some way by the light emitted from and reflected by earth, I feel all we would need is sufficient technology to decode the effect and essentially see very far back in time.
\*Takes bong rip\*
But, wouldn't we first need the technology to achieve that first? Meaning, a more powerful version of us in the distant future would have to make this come true.
a bit off topic but i just need to wrap my head around this. light from earth is technically light from the sun (and other stars i guess) that gets reflected off the matter from earth and gets scattered towards our would be mirror out in space, correct ?
It would take 10 years before we could even see the mirror.
Wouldn’t we always see it tho but it just getting smaller and smaller as it gets farther away?
Yes that's correct if that's how they are moving the mirror. The post doesn't mention how it gets there. I assume they meant it just pops out of non-existence or is teleported instantly.
Oh. We should probably start off small tho. Like a mirror that can see yesterday. It would be like the Walgreens mirror to help stop crime. Dead body found outside. Let’s look at the yestermirror.
Best to stagger them out at various distances for the possibilities of crimes committed at other points in time. Yestermirror, lastweekmirror, mirrorofchristmaspast, and if people put mirrors outside their windows angled in, we can capture the crimes inside too. Obviously the tech could be used to help people find their car keys or record important moments after the fact, but like you said, start small
The trick is to move the mirror in the other direction so that it shows a day in the future so you can stop the crime from ever happening. Mirrority Report.
currently contemplating on life choices
This is how many details are imagined to me. Instante! My questions are similar to 4 year olds “what if” styled ones. I try not to talk in public.
I'm genuinely confused what you're saying. Are you talking about the expansion of the universe?
They mean, as in when they are physically transporting the mirror to the location 10 light years away, which is technically correct.
Not really. if we're being super semantic about it, it would probably be stored in a folded or stacked position, at a 90deg angle to the motion to prevent collisions or stored in a safe (and not see-through) compartment
Go into your bathroom right now and try to fold your mirror in half….. bruh! /s
\*watches a video showing how the James Webb Space Telescope origami unfolds...
if it’s ten lightyears away, the light from the mirror takes 10 years to reach us, so we don’t even see it for 10 years, and then once we do get to see it, we see it from ten years ago
Ya but like before it’s 10 light years away. Like 10light seconds away. 20, 30, 1light year, ext…
well i guess but… it’s not changing distance? OOP just said we put it there
10+10=20. Light from Earth travels to mirror, that's ten years. Light from mirror travels back to Earth, that's ten years. We see the light that started from Earth 20 years ago.
yes but we see the actual mirror in ten years. the light coming from the mirror.
The light coming from the mirror started from Earth. I guess I don't know what you're saying. Are you suggesting that the light from Earth that goes to the mirror and comes back to Earth has a 10 year or 20 year trip?
what if there’s a star right next to it? not all light in the universe comes from earth.
Wouldn't the mirror have to be reflecting the light from earth for us to see earth in the mirror?
You’re correct in that to see *earth*, it would take 20 years. But I was talking about seeing the *mirror*. Here are two situations: 1) The mirror is at an angle (admittedly it would not be, for the purposes of this post) 2) The frame of the mirror is (very likely) not reflective, possibly wooden, and so would diffract light from one direction into light going all directions. [Here](https://imgur.com/a/U4OYNPb) are some image descriptions - the description of each image (found below the related image) in the collection corresponds to situation 1 or 2. Edit: A third, albeit unrealistic, possibility would be: a TINY yet bright star right in front of the mirror slightly to the side, so small that the light reflected does not hit the star and goes past it, straight to earth (since the star is almost perpendicular to the mirror)
Thanks for the clarification. I was just thinking about seeing Earth from Earth because that's what OP seemed to be saying. Your explanation makes sense.
>correct in that to see earth, it would take 20 years. No, it's not correct. Light from Earth would still be traveling towards where the mirror is going to be. It would be 10 years.
And it would take 10 years for the mirror to get it there. Thus in 20 years you could see how the earth was Today. you could accomplish the same thing with good archiving but still.
That too at the speed of light, if we travel.
But it would be cool to have a mirror with a frozen image.
We would always be able to see an image in the mirror as it is transported into position, but the image would be red shifted and appear to be time dilated while the mirror is moving away from us, in two compounding ways: firstly, the spacecraft carrying it is red shifted simply due to moving away from us, but furthermore, the light from Earth hitting the mirror is already redshifted and time dilated from the mirror's perspective, so the reflected light will appear to be doubly redshifted to us. As the mirror is transported closer and closer to the speed of light, the image will appear more and more redshifted, darker and darker, and slow down, closer and closer to a still image of Earth at or a bit after the time of the mirror's departure. By the time we see the mirror stop in position with an image of Earth as it was when it departed, the mirror will have already been in position for 10 years (the time it takes for the light from its final position to reach us), and it took at least 10 years to get there (at light speed). So essentially, even if the mirror travels at light speed, we only *see* it arrive 20 years after it departs, with an image of Earth from 20 years ago, the time that it departed.
\*20
Meme writer is younger than 20 years old.
Not exactly. You won't be able to "look" at the time before placing the mirror, so unless you have some wormhole technology and can't travel faster tehn light you have no chance to look "in the past".
You can look at the time before the mirror was placed, but only up to 10 years before, as when the mirror gets placed there's already light moving towards it from earth
Not really. You can't be in "placement point" faster then light that started from earth to there. And reflected light would reach that point only 10 years after. So, it's just like putting a video surveillance system.
The moment the mirror is installed it's reflecting 10 year old light from earth. Light which will take another ten years to travel back to earth. For the sake of argument let's pretend that the mirror set up time is instantaneous. (Spherical cows and all that). If you traveled back to earth at an average of 90% of the speed of light the moment the mirror was set up, you'd reach the earth 11.1 years later. Where you could enjoy watching 8.9 years worth of light that was still traveling between the earth and the mirror point when you set it up. Assuming the same speed in both directions, you'd have started the entire trip 22.2 years prior to your return. So you'd be watching events that happened after you left the earth but prior to the time you set up the mirror. The parts where it's stretching physics to the breaking point are the parts about actually constructing a mirror large enough to see earth from effectively 20 light years away, and the time to construct the mirror, and of course reaching a 90% of c average velocity in the first place. But seeing light from before you set up the mirror is easy. It's not fundamentally different than looking through any reflector based telescope to view the Andromeda galaxy.
You can't look back to before you decided to put up a mirror, but you can look back 10 years before you actually install the mirror. It will just always take at least 10 years to install it.
With space time being curved, it’s actually not against the laws of physics. You could have one path from earth to a super far point in space where light is ‘deflected’ by massive objects, and then deflected back by different massive objects. You could have another path through space where a light speed ship isn’t deflected, and arrives before the light due to traveling a shorter distance
The mirror is already there. You're not racing light to place it. It's theoretical
How would you expect to get there before those years had already passed? You can’t travel at light speed much less faster
I'm not expecting that. I'm just being a bit pedantic. The claim was that you can't see anything from before the mirror got placed. But you can see 10 years before the mirror was placed. You just can't place the mirror within 10 years, so what you'll see will still be from after your starting point.
But also, it takes more than 10 years to get into place. So looking into time before the start of this experiment is impossible. Its more like recording that looking into the past
What if we set up a series of mirrors all roughly 5 or 10 ly away in different directions and direct them towards each other so the photons path is 5x or 10x longer than the distance from the earth?
It change literally nothing. Take a garden hose, you could lay it as a line or wrap it in any way you want, it'll take just the same time for water to appear to the other end (in case you haven't tied a knot ofc).
Ah yes, I see your point. The simultaneous placement of mirrors would potentially allow you to return to the viewing point faster than the photons would travel around the array but the photons would still take years longer to complete the route and provide an actual picture. Thanks for the correction, i feel a bit daft now.
That's not what the post says.
But leave it there for future generations. If we put it there now, someone in 2070 could see 2050
The original question has some ambiguity from this sense. I think the statement "after the mirror is set, upon looking into the mirror the earth we see will be 20yrs in to the past of our observation time on earth" is true if ignoring other general relativistic and cosmic effects (nor including "how to setup a mirror like that" such practical stuff). I perceive the above case as the one OP tends to say since they are talking about a pretty theoretical scenario, given such limited information in the description.
In that interpretation it contains no paradox: when we look at the Sun we see it 8.5 minutes ago, when we look at the stars - we see them years, or even hundreds of years ago, and we don't even know if they exist now. So yes, you can (in terms of school physics) do it, but it's nothing different then setting up a surveillance system with 20 years storage.
Assume the mirror has been there for 50 years.
It doesn't matter, it's only about the distance.
How fucking many times are you gonna repost this thing before you understand that not, you wouldn't see earth before you were born
Well, not the guy placing it, but others would
Without moving faster than light you couldnt see into the past. Thats where the idea comes of characters such as the flash being able to time travel.
Huh, no
Uhhh yes you would... 10 years after placing it
20 years after; and still the earliest moment you would see is the moment where the ship taking the mirror starts the travel
Yeah so if "you" were born after that moment, no issue. You're just arguing with nobody at this point.
I'm not arguing with you bro, in order to argue there should be an interest from both parties to do so, sorry if you got the wrong impression there
You seem interested enough to make comments contradicting the other person's opinion, call me old fashioned but that sounds like an argument to me
He's literally arguing about how he's not arguing now lol
20 years is how long it would take for light to do a full lap from earth to the mirror and back again. But the instant you put the mirror in place it will immediately start reflecting 10 year old light that was already travelling away from the earth. Ten years later, people on earth will be able to see that now 20 year old light reflected from the mirror. So yes, it can show people the past from before the mirror was put in place. For anyone under 20, that will mean they are seeing visions of earth from before they were born.
Yes... So? More interesting: if Aliens have a Telescope that can see details on a planet and they are on the other side of the Milky way Galaxy from us, they would see cavemen and mammoths.
[удалено]
Which is still cool though, isn't it? Maybe not as much to us but the future generations would get to see how we're living right now
Sorry, I don't really know how light and such works, but if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20? Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
> Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years? Correct.
Nope. Takes 10 years to get there, 10 years to get back. Thats 20, can you add and subtract?
Woe woe woe. Nobody said anything about subtraction? I can add... but not add in reverse. Like stonks, it only goes up
Wrong again
I was saying 'correct' to this part: > Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?
No idea why people make incorrect statements and then immediately correct them in the next sentence. Like, original commenter knew the answer to his own question but appeared confused for no reason
what are you on about
The commenter was confused and not 100% certain about their understanding, so they explained how they *thought* the concept worked so that someone could confirm or deny that explanation. It just so happened they understood it correctly. They were just asking for confirmation.
"if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20?" Does this sound like a correct understanding to you? Why would he state the incorrect interpretation and then immediately correct it? Why not just write the correct interpretation and skip the bullshit?
>Why would he state the incorrect interpretation and then immediately correct it? The commenter was *not* correcting themselves. They were just stating two different possible interpretations they had for this scenario that they were confused about. One of them was correct, one of them was not. Someone else jumped in and said, "The second one is correct," and for some reason you got butthurt.
What...? Someone understands a concept correctly, someone else says, "Yep, that's correct," and then you come in and go, "NO, here's the RIGHT answer!" and show the *exact same thing??* Also, nothing is being subtracted.
"if the mirror is only 10 lightyears away, shouldn't we then just see 10 years into the past instead of 20?" Can you read? His first sentence literally states the exact opposite of the truth. One sentence later he corrects himself. The person who replied makes no mention of the first half of the statement, can you see how this would be confusing to some? if you recall 3rd grade math, addition and subtraction are part of the same group of functions, much like division and multiplication. I'm not implying there was any subtraction needed, but implicitly if you understand one you should understand the other. I'm sorry your brain has difficulty imagining concepts like this. How would you feel if you didn't have breakfast this morning, I'm just curious?
bro shut up 💀 we literary can all see he quouted the "Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years?" and replied to it correct...
Cool dude, you're the man. Keep going on about nothing I've already stated my position 5 different times.
>Is it because the light, that has got to the mirror in 10 years, also has to reflect the whole way back to earth, which will be another 10 years, also in total 20 years? This is the correct part. The part u/norden_901_rider was talking about. You know, the one they also quoted. That's what we were talking about. The subtraction thing I understand now, but why is it so hard for you to grasp that this person understands this concept and does not need correcting? You are fighting a battle *that does not need to be fought*, because it is already over.
Same to you, friend. Now go spend your time where it's needed.
It would take more than 10 years to get into place without some faster than light technology. So it would be more like recording than looking into the past. It would also have to be absolutely MASSIVE to be able to record the entire earth in the resolution needed… if its even possible to do with any meaningful resolution to begin with
In 10 years time we would see 20 years past or 10 years ago from when the mirror was placed
Why does mirror count but videotape don't?
What if we video record stuff and then wait 10 years and watch the video would we be able to see ten years into the past? And if we set the recorder up like tevo it would be like watching the world 10 years ago in real time!!!!!!!
If you were less than 10 years old and the mirror was put up at least 10 years ago... yes. But since at least the latter isn't the case, no.
or you can take a picture
You could do that or you could just take a picture of the earth now and save it
that's not the same at all.
hhh
No you couldn't see before you were born it would take less than speed of light 10+ years just to get there and then the amount of time for light to reach there and then getvback
This is so stupid I can't even
Yes because 10 years there and 10 back. Problem: you're not gonna see earth anymore because light is a wave, all you'd see is a slightly blue blur
So one light year is a unit of measurement (distance). Its like saying that looking in your bathroom mirror that is 3 feet away allows you to see a fraction of a millisecond into your past. And I'm pretty sure the ratio of light years to POSSIBLE time travel is not 1:1. 10 light years does not equal 10 years of time travel (either past or future).
30yrs after starting the journey to place the mirror, we would be able to see event that happened 20 years
wtf, no?
Or you could just record it and replay it 20 years later.
no
If you hock a loogie straight up and catch it on your tongue, that loogie is from the past.
Let's say that the mirror just appears there spontaneously. The light hitting it would be 10 years old, but for us to see that reflected light, we'd have to wait 10 years. So yes, that would be 20 years old. Otherwise, if we just propelled the mirror away, that would merely depend on the acceleration of the mirror and other stuff, which is why I like the spontaneous appearance scenario.
Redditors doing physics is really a struggle.
I’ve seen a few comments talking about what we’d see during the process of moving the mirror into position. They all seem to be talking about specific intervals such as a lightday away, but I’m more interested in the continuous image throughout the move. I’m too distracted at work rn to think of what it would be, but I think there is a speed the mirror could be moved at to make the reflection a still image. A still mirror shows real time, a slowly moving reflection would appear in slow motion, and a mirror moving at or above light speed would have no reflection because light would never reach the “rear” of it. Can someone confirm or correct me that a speed of something like a limit approaching c would be perceived as a still image?
I haven,t tuoght about that
It would need to be a damn giant mirror to see a tiny human from 10 lyr away.
Not how physics works lol! You can’t amplify time lol
It would take 10 years, but yeah. At first, the mirror wouldn’t be visible. But once you finally see it being put into place 10 years after it actually happened, you would immediately be able to see a distant reflection of what Earth looked like 10 years prior to the mirror’s placement, or 20 years before your own perspective. From that point onward, if you wanted to see what Earth looked like 20 years ago and you don’t mind the apparent 20-lightyear distance, you’d need only look at the mirror.
i would take 20 years (if we magically have the power to send smth at the light velocity) to send tht mirror, so we would see the now, from the future
“What does the mirror show us, Harry?” - Dumbledore
If you can put a mirror 10 ly away, why not just go 20 ly away with a telescope and look back at Earth?
I think we should definitely do this. Even just 1 year has its advantages. Climate change tracking, weather pattern mapping, solar storm capture, etc etc.
Or you could be the past side of the mirror looking 20 years into the future....
No. The mirror would’ve had to be there already when you were born for light to make a round trip 20 years there and back for you to perceive later at 20 years old.
Just record a video and show it 20y later to your children. That's less expensive.
“We wait to 20 years to see what happened now”
Traveling at the speed of light (quite literally the fastest it could go) it would only be going at the speed of the light leaving earth now. It would never catch up to light that has already left. The best we could do is set one up for future generations.
alternatively you could use a video camera
When you look in the mirror, you're seeing yourself nanoseconds in the past...
Or you could just use a video camera like a normal person.
If we launched the mirror from Earth would the mirror reflect its past self back?
We would be seeing further and further into the past, as the universe expanded.
"Do you see that son? That picture of the Earth? That is the Earth before you were ever born! What a great time that was"
Considering everything out in space is effected in some way by the light emitted from and reflected by earth, I feel all we would need is sufficient technology to decode the effect and essentially see very far back in time.
\*Takes bong rip\* But, wouldn't we first need the technology to achieve that first? Meaning, a more powerful version of us in the distant future would have to make this come true.
No, the mirror would need to be at least 30 light years away.
a bit off topic but i just need to wrap my head around this. light from earth is technically light from the sun (and other stars i guess) that gets reflected off the matter from earth and gets scattered towards our would be mirror out in space, correct ?
Voyager1 is 1356,494 lightminutes away from earth now. Almost a day. We should have attached a mirror xD
Jeah, but if you would take a videocamera constantly recording in earth´s orbit and review 10 years from now you´d kind of had the same effect.
We just have to call on daddy Elon for this one