Exploring the Possibility of Seeing the Past: A Scientific Perspective

  • Thread starter terencesiu
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In summary: So if you want to observe a planet that is billions of miles away, you would have to wait a long time for the signal to travel to your Earth. However, since we can see the past of a planet by looking at its relative past, we can get a sense of what that planet was like before we observed it.What device? We don't have a device.
  • #1
terencesiu
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I am watching a movie about a person who can see the future. I have thought a lot of time and I think it is impossible, but how if we see the past? In fact, we can see the relative past of a planet which is far far away, since time is needed for light to pass to our eyes. But can we do that on a very short distance, by decreasing the speed of light/sound/etc? Does it possible? And are there any research about it? thank you.

My English is poor, hope you understand it.
 
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  • #2
There is no way to decrease the speed of light.
 
  • #3
then, how about decrease the speed of sound, by making the medium tends to be vacuum? Can we hear the voice from the past?
 
  • #4
terencesiu said:
then, how about decrease the speed of sound, by making the medium tends to be vacuum? Can we hear the voice from the past?

Rarefying the medium slows the sound down but not appreciably, not practically.

Note that, even if you could find a way of making a light or sound signal travel slower, it would not allow you to see or listen to the past. It would simply mean any signal you sent after the device was in place would travel slower - which is pretty useless.

For example: email takes a few seconds to get from point to point around the Earth. If you slowed this transit time down to a year, you would not start getting emails from last year. No, it would simply mean that, when people started sending emails today, they would now take a month to arrive.
 
  • #5
DaveC426913 said:
Rarefying the medium slows the sound down but not appreciably, not practically.

Note that, even if you could find a way of making a light or sound signal travel slower, it would not allow you to see or listen to the past. It would simply mean any signal you sent after the device was in place would travel slower - which is pretty useless.

For example: email takes a few seconds to get from point to point around the Earth. If you slowed this transit time down to a year, you would not start getting emails from last year. No, it would simply mean that, when people started sending emails today, they would now take a month to arrive.

I can mostly understand,
does it means that we can see the past of planets is because the medium "space" is already exists?
but, really thank you!:smile:
 
  • #6
terencesiu said:
I can mostly understand,
does it means that we can see the past of planets is because the medium "space" is already exists?
but, really thank you!:smile:

No. Light does not need a medium to travel through.

It is kind of academic to talk about seeing the past of a distant planet. Since c is the speed limit on any connection between distant points, it is kind of meaningless to compare a point at our "present" with some point at a distant planet's "present".
 
  • #7
DaveC426913 said:
No. Light does not need a medium to travel through.

It is kind of academic to talk about seeing the past of a distant planet. Since c is the speed limit on any connection between distant points, it is kind of meaningless to compare a point at our "present" with some point at a distant planet's "present".
:confused: I think I have more and more questions. How does the people can observe the planet? Do they get the picture of the planet instantly, or just get the picture after the device have been set up for a long period? If they can get the message instantly, does it means that we can see the past after the speed slowing device have been operated for a long period? I think it will be funny if it can be made.
 
  • #8
terencesiu said:
:confused: I think I have more and more questions. How does the people can observe the planet? Do they get the picture of the planet instantly, or just get the picture after the device have been set up for a long period? If they can get the message instantly, does it means that we can see the past after the speed slowing device have been operated for a long period? I think it will be funny if it can be made.

What device? We don't have a device.

Our devices for observing planets are telescopes, which of course are limited to the speed of light.
 

1. Can we actually see the past?

Technically, no. The past has already occurred and what we perceive as the present is actually the past. However, we can use various scientific methods to observe and learn about events that have already happened, such as through historical records or studying light from distant objects.

2. How far back in time can we see?

The furthest we can see depends on the method of observation. For example, with telescopes, we can see objects that are billions of light-years away, allowing us to see light that has traveled for billions of years. However, there are limitations to our ability to observe the past, such as the speed of light and the age of the universe.

3. Can we see events that happened before the Big Bang?

No, the Big Bang is considered the beginning of the universe and any events that occurred before it are currently beyond our ability to observe. This is because the universe was incredibly dense and hot during this time, making it impossible for light to travel and be observed.

4. How accurate are our observations of the past?

The accuracy of our observations depends on the quality and reliability of the data we are using. For example, studying historical records can provide relatively accurate information about events that occurred in the past. However, when studying distant objects, there may be limitations and uncertainties in our measurements that can affect the accuracy of our observations.

5. Is it possible to change the past through observation?

No, observing the past does not have the power to change or alter it. Our ability to observe the past is limited to studying and learning from events that have already occurred. Changing the past is currently considered impossible according to our understanding of physics and the laws of causality.

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