# Space, Reflection: See Earth's Past in Mirror?

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• atarah
In summary, placing a mirror in space to take a photo of Earth's reflection and see it in the past is theoretically possible, but the time it would take to set up the mirror would limit the amount of time you could see into the past. However, using a bathroom mirror could provide a small delay of about 10 nanoseconds.
atarah
TL;DR Summary
can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?

We don’t even need a mirror to produce that effect. When I see a fly land on a table 3 meters away…. The fly actually landed about 10 nanoseconds before I saw it land, because that’s how long it took the light to travel the 3 meters between the table and my eye. The same thing would happen if we were using a camera instead of a human eye to form the image.

And yes, sending the light on a circuitous path with one or more mirrors allows us to introduce yet more lag between event and eye. In practice however, we’re not going to be able to get more than a tiny fraction of a second of additional delay that way.

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atarah said:
Summary: can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
Unless the mirror is already there, getting it set up will require so much time that you'll not see any farther into the past than when you launched it.

So if you are planning on getting some long distance images of the grassy knoll at a particular historically relevant moment, you are out of luck.

Mister T and phinds

phinds
atarah said:
Summary: can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?

can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
Your bathroom mirror will give you a delay of ten nanoseconds or so. that would be a start!

phinds

## 1. What is the concept of "Space, Reflection: See Earth's Past in Mirror?"

The concept of "Space, Reflection: See Earth's Past in Mirror" refers to the idea that when we observe distant objects in space, we are essentially looking back in time. This is because light takes time to travel through space, so the light we see from distant objects has been traveling for thousands or even millions of years, giving us a glimpse into the past.

## 2. How far back in time can we see with this concept?

The farthest we can see back in time with this concept is approximately 13.8 billion years, which is the estimated age of the universe. This is because the light from the most distant objects in the universe has been traveling for that amount of time to reach us.

## 3. How does this concept help us understand the history of Earth?

This concept helps us understand the history of Earth by allowing us to observe distant objects in space that are actually images of how those objects looked in the past. By studying these images, we can gain insights into the formation and evolution of our own planet and the universe as a whole.

## 4. Can we use this concept to see events that happened on Earth in the past?

No, we cannot use this concept to see events that happened on Earth in the past. This is because the light from Earth's past events has already reached us and is no longer traveling through space. However, we can use other methods such as studying geological and fossil records to learn about Earth's past.

## 5. Are there any limitations to this concept?

Yes, there are limitations to this concept. One limitation is that the farther we look into space, the more distorted the images become due to the expansion of the universe. Additionally, some objects may be too far away for their light to ever reach us, meaning we will never be able to see their past. Another limitation is that we can only see as far back in time as the existence of the universe itself, so we cannot see anything that may have happened before the Big Bang.

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