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Author Topic: Looking at the past  (Read 3860 times)

Offline Ricardo Pedri Lopes

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Looking at the past
« on: 21/12/2010 02:09:32 »
Take a look at this guy's hypothesis and say what you think about it.

newbielink:http://gerakanjohor.blogspot.com/2007/11/how-to-see-past.html [nonactive]


 

Offline CPT ArkAngel

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Looking at the past
« Reply #1 on: 21/12/2010 02:48:25 »
We have already a machine to look in the past, it is called a camera... :D But it it possible to send a satellite 10 light years away and it would feed us an image from 20 years earlier... But there is better ways to do the same... You just need to delay information.

Secondly, you cannot go faster than light... The speed of light and time are inseparable.

You can possibly transfer information instantly to another point in the Universe by quantum entanglement. But it would be instantly, not in the past...
« Last Edit: 21/12/2010 05:22:58 by CPT ArkAngel »
 

Offline Don_1

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Looking at the past
« Reply #2 on: 21/12/2010 09:15:21 »
I can read yesterday's newspapers to see the past, or, as ArkAngel wrote, look at some old photos.

The light we see from the Sun and other stars is from the past. And yes, even looking in a mirror I am seeing me in the past, albeit the very recent past.

If I could travel at the speed of light, all around me would appear to stand still and if I could travel at speeds in excess of the speed of light, all around me would appear to go backwards, but I cant travel at those speeds and never will.

Since travel beyond the speed of light is not possible and wormholes are pure fantasy, I can't get to a point where I could see light from Earth which is 2000 years old, so no chance of establishing the truth about Christmas. Even if I could, the image would have to be magnified a few billion times more than we are capable of today, so the whole affair is purely academic anyway.
 

Offline imatfaal

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Looking at the past
« Reply #3 on: 21/12/2010 10:57:08 »
You can possibly transfer information instantly to another point in the Universe by quantum entanglement. But it would be instantly, not in the past...

How? - aside from all the sci-fi nonsense in popular press about pairs of entangled particles I have never seen a way of transmitting information.
 

Offline Ricardo Pedri Lopes

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Looking at the past
« Reply #4 on: 21/12/2010 13:36:47 »
But there is better ways to do the same... You just need to delay information.

Hello ArkAngel, what do you mean by delaying information?
 

Offline Bored chemist

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Looking at the past
« Reply #5 on: 21/12/2010 16:25:18 »
You can find out what is happening (more or less) now by watching the news on TV. If you recorded that news and sent it by post you would delay it by a few days. The people watching the old recordings would be looking at the past.
Any way of delaying the data will mean you look at the past. In fact ,since the light always takes a some time to reach your eyes and get processed by the brain, we are always looking at the past.
Looking at "Now" would  be a challenge.
Looking at the future would let us win next week's lottery which would be much more useful but leads to potential contradictions and paradoxes.
Imagine I read next week's papers and find that I die in a car crash tomorrow. Having read that, I decide to stay in bed so I don't get killed. Where did the story of the crash come from?
 

Offline CPT ArkAngel

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« Reply #6 on: 22/12/2010 03:08:33 »
I don't understand why you could not communicate instantly between 2 communication devices using entangled particles... It is only theoretical but many experiments tend to prove it...

See applications:

http://en.wikipedia.org/wiki/Quantum_entanglement

and see: 4. EPR (Einstein–Podolsky–Rosen) paradox

http://en.wikipedia.org/wiki/Copenhagen_interpretation
« Last Edit: 22/12/2010 03:13:39 by CPT ArkAngel »
 

Offline CPT ArkAngel

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Looking at the past
« Reply #7 on: 22/12/2010 03:22:47 »
Since travel beyond the speed of light is not possible and wormholes are pure fantasy,

Wormholes could be doors to an entangled antimatter Universe and you wouldn't need to go faster than light to travel there (but i wouldn't recommend to do it...:-))

With wormholes, you don't go faster than light, it is space itself that is shorter, but it is a theory...
« Last Edit: 22/12/2010 03:24:35 by CPT ArkAngel »
 

Offline JP

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Looking at the past
« Reply #8 on: 22/12/2010 03:38:27 »
I don't understand why you could not communicate instantly between 2 communication devices using entangled particles... It is only theoretical but many experiments tend to prove it...

The proof that you can't communicate is somewhat complicated, but it basically comes down to the fact that you have to choose between two different ways to send that data and two corresponding ways to measure the data.  If the sending and measuring processes don't agree, the data received is useless.  The catch is that in order to agree on these processes, they need to send classical information, which is limited by the speed of light.

So even if they made a bunch of measurements faster than a phone call could happen, the receiver wouldn't know which data contained information and which was noise until that phone call arrived--at the speed of light or slower.
 

Offline CPT ArkAngel

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« Reply #9 on: 22/12/2010 04:05:21 »
It is according to what we know now... Maybe we will find another way to measure it... If you have a neverending parallel communication, you just need a measurement of a change in the spins, but we need a constant control of the spins of the emitter particles.
 

Offline JP

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Looking at the past
« Reply #10 on: 22/12/2010 05:58:01 »
There's also the neat science fiction idea of making a window made out of some material that slows light down to a crawl.  If you put the window next to a nice scenic meadow for a long time, and then hung it up against a blank concrete wall in your house, it would begin to play back the recorded scene of the meadow as the light slowly crept through the material.  This is basically the same effect as storing the light coming off a scene for a long time, and then finally sending it to your eyes.
 

Offline CliffordK

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Looking at the past
« Reply #11 on: 22/12/2010 07:35:56 »
The "Holy Grail" of time travel is to be able to see something that is happening in the future, not the past.

When we look at Alpha/Proxima Centauri, we see light that was emitted from the stars 4 years ago.  But, we know that events have happened on those stars since that time.

In fact, we wouldn't know if one of the stars was obliterated by some strange force today for another 4 years.

If we had some kind of "Warp" travel, we might just get the news faster.

This isn't really any different from the 18th century when it would take months for news to travel from the Americas to Europe.  Everybody knew that the "news" was happening on the other side of the sea.  They just had wait for it to arrive.

If one had some broad spectrum transmitter so one could see everything that was happening, then it might be interesting.  But it is unlikely you'd see anything that one couldn't just time-delay in the exhibition.

Or, if you wished to waste bandwidth, you could do a circular loop of data transmission around our satellite network.
 

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Looking at the past
« Reply #11 on: 22/12/2010 07:35:56 »

 

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