Time Travel

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Matt
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Post by Matt » Mon Feb 26, 2007 11:26 am

A possibility? Scientists seem to think so.

Dreams of time travel go as far back as Newton. Einstein certainly believed it was possible to go forwards in time, however, not backwards in time. I watched a video investigating the whole idea including Einsteins theory as well as newer ones.

Armed with this knowledge. I still find myself disputing what scientists say. How is it possible for a person to meet their former self? There is only one me.

Using the last segment of program as the best example (despite it needing 3 times the mass of our galaxy to do so, or something like that) using cosmic strings in space. I still find it utterly impossible to fly from planet A, to planet B and then back again to meet my former self.

I can't get my head around it :( The idea is a brilliant fantasy, but not one I can ever envisage.
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Post by Chewi » Mon Feb 26, 2007 1:41 pm

When I was younger, I read a childrens book on the theory of relativity. It was about a boy and his Uncle Albert. The funny thing is, it made perfect sense to me at the time but now I can't remember how it worked. I wish I could read that book again.
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Post by Chewi » Mon Feb 26, 2007 2:30 pm

I haven't watched the video but does it actually mention meeting yourself? If you go forwards in time, how can you meet yourself unless you subsequently go back afterwards? This would also be a paradox but let's not go down that route. As you say, there is only one you. Say you travel ten years into the future, you would continue to exist for that ten years but you would experience time at a faster rate and so it would seem shorter than ten years. The journey isn't instantaneous like in most time travel fiction - though it could be argued that if enough energy was applied, it could effectively be instantaneous, say, in the order of seconds.

Here's an analogy for you. Grab a pen and start drawing a straight line slowly from left to right. You can speed up and slow down but you can't stop, you can't change direction and you can't take the pen off the page. That is the nature of an object through time.
Last edited by Chewi on Mon Feb 26, 2007 2:35 pm, edited 1 time in total.
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Post by Bogey » Mon Feb 26, 2007 4:30 pm

Aren't timetravel theories just loopholes in the written laws of physics? That's how I always saw them.
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Post by Super Goat Weed » Mon Feb 26, 2007 4:42 pm

Check this out:

In the Science News, Vol. 160, October 6, 2001, Peter Weiss wrote an article entitled Constant Changes - If a constant of nature can vary, then so might laws of physics.

Here's some quotes.
"Sometimes it’s the tiniest differences that change everything. This summer, astrophysicists reported tantalizing evidence of just such a discrepancy."

"Using one of the world’s largest telescopes, a team of Australian, British, and U.S. astrophysicists observed clouds of gas in space backlit by beams of radiation from ancient, super powerful quasars."

"By doing so, they have found evidence that one of the constants of nature, which are never ever supposed to vary, was smaller billions of years ago than it is today. The quantity that was measured, known as alpha, wasn’t smaller by much - less than 1 part in 100,000 - but the finding has sent tremors through physics and astronomy."

"‘Atoms, the whole periodic table, and the way it exists are dependent on the value’ of alpha, notes Barry N. Taylor of the National Institute of Standards and Technology (NIST) in Gaithersburg, MD. ‘If alpha didn’t have the value it has, Earth as we know it wouldn’t exist,’ he adds."

". . . Although no flaw has been found so far in the study, researchers are rushing to measure alpha’s ancient value by other approaches that wouldn’t be prone to the same potential sources of error."

"Alpha is known formally as the fine-structure constant. . . . NIST defines this constant as ‘the strength of the electromagnetic force that governs how electrically charged elementary particles (e.g., electrons, muons) and light (photons) interact.’" [Emphasis added]

"Since the universe was born some 15 billion years ago, it has ceaselessly expanded and changed. Nonetheless, a few characteristics of the cosmos appear to have remained immutable across all of space and time. These fundamental constants of nature include alpha, the gravitational constant, and the speed of light in a vacuum."

"The constants have been viewed as fixtures of reality. They are part of the foundation of physics, embedded deeply in both the classical science and quantum mechanics, as well as in relativity and the so-called standard model of particle physics."

"If the measured variation in alpha turns out to be real, then one of the most basic assumptions of science - that the laws of physics are the same everywhere and at all times - will prove untrue, notes Michael S. Turner of the university of Chicago."

"’Constants are invented by man to help him describe the natural world that he sees.’ . . . points out Taylor, a physicist who since the 1960s has been a leader in assessing the values of constants."

" . . . ‘There’s a whole industry of people thinking about the variation of constants,’ Taylor notes."

"Since the late 1960s, observers have been checking to see whether the spacings between the absorption lines in quasar spectra differ slightly from those observed in laboratory experiments. According to theory, alpha is one of the factors that affects the size of the spacings. So, if alpha during the earlier phases of the universe was slightly off from today’s value, that difference might show up in the spectra of quasar light traversing gas clouds on its way to Earth."

"That’s where the new spectral measurements that Webb and his colleagues harvested come in. In the August 27 [2001] Physical Review Letters, they present data suggesting that the spacings between absorption lines for several types of atoms 8 to 12 billion years ago were different than they are today."

" . . . More evidence of the discrepancy appears to be on the way. Webb says that a preliminary analysis of an additional set of observations twice as extensive as the one described in the August 27 report also indicates that alpha was once a wee bit smaller than today."

" . . . Adds Taylor, ‘To the best of my knowledge, there’s been no definitive observation of a time variation in a constant. This case may be the strongest that we’ve seen.’"

"One of the most profound implications for science would be that the presumption of immutability for the laws of physics may be wrong."
Oddly enough, i haven't found any follow up articles on this

Anyway, if what they are saying is true, then the laws of physics are a bit more flexable then scientists had originally though, meaning, in a sense, just about anything is possible.

However, i don't believe we can actually travel backwards in time. Reason being, if it WERE possible, we'd know about it already, since someone would have already done it. It may be possible to 'probe' time, in a sense of looking into the past, but actually participating in and or altering it would be impossible.
Last edited by Super Goat Weed on Mon Feb 26, 2007 4:43 pm, edited 1 time in total.
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Post by kaos » Mon Feb 26, 2007 4:43 pm

Chewi wrote:Here's an analogy for you. Grab a pen and start drawing a straight line slowly from left to right. You can speed up and slow down but you can't stop, you can't change direction and you can't take the pen off the page. That is the nature of an object through time.

Most people think time is like a river, that flows swift and sure in one direction. But I have seen the face of time, and I can tell you, they are wrong. Time is an ocean in a storm. You may wonder who I really am and why I say this. Come, and I will tell you a tale like none you have ever heard....
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Post by Mik » Mon Feb 26, 2007 4:49 pm

The whole arguement of, it timetravel where possible we'd already know is fairly flawed, thre are just some thing you don't report to CNN. Imagine this a dude traves in time and is like 'I'm from the future' ... your not going to believe him.

Okay imagine we have this technology now and you go back 200 years in time so it's now 1807, Convince someone your from 2007 your from the future. The only think I can think of is a mobile phone can only for the picture aspect cause you can't get reception cause there are no satelites . well bar the moon but it's not a cell tower .. yet.
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Post by Chewi » Mon Feb 26, 2007 4:54 pm

The more I learn about physics, the more flexible it turns out to be. Talk of bending space in the form of wormholes and such. But it's all highly theoretical. I used to live with a physics student. As for going backwards in time, I do believe that is impossible but it is possible to look backwards in time because light travels at a finite speed. When we look through our telescopes, we are seeing things that happened millions of years ago simply because the light takes that long to reach us - hence the term light-years. If the sun was going to explode or something, we wouldn't see it starting for about 10 minutes. Mind you, we probably wouldn't see it starting at all because we'd be splattered across the galaxy by then. :P
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Post by Mik » Mon Feb 26, 2007 5:03 pm

As far as I was aware the speed of light wasn't as constant as they used to think.


Also in order for you to look back at the earth from space ina far off enough place to see the earth x number of years ago you'd need to travel faster than the speed of light and in order to see anything worthwhile one fucking good pair of binoculars.
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Post by Super Goat Weed » Mon Feb 26, 2007 5:06 pm

Actually James, the quotes i just posted had a lot to do with light's speed NOT being a constant.

There's really very little that is apparently.
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Post by kaos » Mon Feb 26, 2007 5:10 pm

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Post by Chewi » Mon Feb 26, 2007 5:28 pm

Hehe I was wondering where that was from.

I never said the speed of light is constant, I said it was finite. It's obvious that the speed of light isn't constant, all you have to do is look at a pen in a glass of water. It looks bent because light travels at a different speed through water. This is called refraction. When scientists talk about the speed of light and light-years, they are usually referring to the speed of light in a vacuum, which is what much of the universe is.
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Post by Super Goat Weed » Mon Feb 26, 2007 6:22 pm

That's exactly the speed of like I'm talking about not being constant, light in the vacuum.

I could be misunderstanding you though.
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Post by Chewi » Mon Feb 26, 2007 6:36 pm

Fair enough, I'm open to the possibility that the speed of light in a vacuum may not be constant. Like you say, it seems that very little is.
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Post by Super Goat Weed » Mon Feb 26, 2007 7:11 pm

you really want to hurt your head? check this out
In July, 2000, scientists at the NEC Research Institute in Princeton reported having accelerated light beyond the speed of light! Their experiment was published in the British journal Nature. They shot a laser beam into a glass chamber containing cesium vapor. The photons from the laser traded energy with the cesium atoms and created a beam exiting the chamber faster than the light beam had entered the chamber.

Light is supposed to travel at its highest speed in a vacuum where there is no resistance, and slower when traveling through any other medium because of the added resistance. For example, everyone is familiar with light traveling slower in water than through air. In the NEC experiment the light beam exited the chamber of cesium vapor before it had even finished entering the chamber.
Last edited by Super Goat Weed on Mon Feb 26, 2007 7:12 pm, edited 1 time in total.
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