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#1 dug nc

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Posted 05 January 2013 - 11:56 AM

As I was perusing my Hubble pics,I started thinking....

We are seeing a Supernova in say,M101:since it is in the past,we could be watching someone's solar system ending.....

and if someone is in another galaxy could they possibly be seeing ours??

And then I wondered,if you were on a vessel going say....2x speed of light & were going toward M33 approx. 3 mill. ly distant:
Would you actually be time traveling? & what would the state of times be both here & there at arrival??
:question:

#2 csrlice12

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Posted 05 January 2013 - 12:08 PM

I'm sure there's a law somewhere's that say's they'll give you a speeding ticket...... :lol:

#3 mjs

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Posted 05 January 2013 - 01:45 PM

Telescopes are indeed time machines in that because light travels at a given speed, it takes a while to get from a distant star to your eye. A distant galaxy, say 100 million light years away, shines on you today with the light that left it 100 million years ago.

As the focus twin paradox shows, you don't have to travel faster than light to make a time machine of sorts. Relativistic effects of moving at close to the speed of light makes time slow down for a clock moving at such speeds compared to another clock which is stationary. If you could make a spaceship which could travel at a substantial fraction of the speed of light and you took a trip on that spaceship you would find upon your return that much more time had passed there that it had for you, moving at relativistic speed. You might still be young while your twin might have died decades ago. So it is a form of time travel, although only one way, into the future.

Mike

#4 killdabuddha

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Posted 05 January 2013 - 01:46 PM

I'm sure there's a law somewhere's that say's they'll give you a speeding ticket...... :lol:


Yeah, like when Heisenberg got pulled over. He didn't know how fast he'd been goin, but that allowed him to know exactly where he was.

#5 Jon Isaacs

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Posted 05 January 2013 - 01:57 PM

I'm sure there's a law somewhere's that say's they'll give you a speeding ticket...... :lol:


Yeah, like when Heisenberg got pulled over. He didn't know how fast he'd been goin, but that allowed him to know exactly where he was.


:rofl5: :rofl2:

Jon

#6 rdandrea

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Posted 05 January 2013 - 01:58 PM

and if someone is in another galaxy could they possibly be seeing ours?



No, because ours hasn't ended yet.

#7 CJK

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Posted 05 January 2013 - 02:08 PM

Yeah, like when Heisenberg got pulled over. He didn't know how fast he'd been goin, but that allowed him to know exactly where he was.


:rimshot:

-- Chris

#8 Cliff Hipsher

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Posted 05 January 2013 - 02:43 PM

That's WAY too simple...

First off, time is a human construct. We need some way to mark the cyclic changes we observe in nature. Things like sun rise, sun set, phases of the moon and so forth became the basis for our measurement of "time."

From a relativistic stand point, the main reason things fall apart as you approach the speed of light is because we don't know what the real unit of measure is for time.

For example, how long is a second? Is it some multiple of a specific radioactive element's decay rate? Is it some multiple of how fast light travels through a given distance?

And what about that distance? How long is a foot, or a meter, or a parsec?

The truth is, we don't know, and until we do know the answers to these questions, the universe is going to be pretty much off limits, and basically we're left on the outside looking in...

To answer your initial questions, if our sun were to go nova, and if someone in a far distant galaxy was looking, they should be able to see the event.

However, as was stated earlier, there would be a considerable time difference between when the event actually happened and when it was observed in another galaxy.

As for time dialiation, that is a local affect caused by moving through space. Within the local space, "time" would appear to proceed at a "normal" rate. To an external observer, local time would remain constant, but the traveler's time would appear to slow down at a rate that is proportional to the traveler's speed through space.

In affect, on a long voyage the traveler would not age at the same rate as non-travelers.

#9 GlennLeDrew

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Posted 05 January 2013 - 05:47 PM

Cliff,
It's not necessary to first 'define' time in order to appreciate relativistic effects, because it's, well, relative.

If you were to travel at near light speed, but beforehand were not aware of time dilation, you'd say upon arrival, "That definitely took less time than I had calculated." And looking at your clock would confirm it. If you were to reach light speed, from *your* point of view you'd travel across the entire universe in an eye blink, not billions of years, or even the seeming great extent of your life time.

#10 Pat at home

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Posted 05 January 2013 - 09:48 PM

As soon as the theoretical physicist finish their unified theory we'll know a bit more. So c'mon folks, get at it, time's a wastin'.

#11 CJK

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Posted 05 January 2013 - 09:56 PM

But at my back I always hear
Time's wing├Ęd chariot hurrying near;
And yonder all before us lie
Deserts of vast eternity.


-- Andrew Marvell (1621-1678)

#12 GeneT

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Posted 05 January 2013 - 10:06 PM

I think I will return to the eyepiece forum. :grin:

#13 Meadeball

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Posted 08 January 2013 - 12:52 PM

Time is an illusion. Lunchtime, doubly so.






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