Physics

I got into an arguement with an old friend in a different forum and I ended up going to one of the heads of theoretical Physics at my University, the University of Michigan. Only a bit of what she said is really applicable here, but here is my 2 cents. She told me that while some particles/waves actually CAN travel faster than light, no information can be transmitted faster than light. Also, she pointed out that theoretical particles know as Tachyons could travel faster than light, but could not travel SLOWER than light. However, these particles as far as we know would not be capable of interacting with our universe so we have no way of proving or disproving their existance.
Also, with regard to changing c. I spoke with another professor and he said that he is not entirely sure if you CAN actually alter c. What he DOES know is that you can pass light through a medium and cause the total travel time to vary, in THEORY changing c. However it is still left to speculation exactly what is happening inside the medium to account for this change. It may be that the light actually is slowing down, OR it could be interacting with the matter and "pausing" as it goes, effectively increasing its travel time, or it could be doing God knows what else...

Something tells me that breaking the light barrier is not impossible. But in much the same way as breaking the speed of sound was considered last century, so too will breaking the light barrier be deemed impossible for this century. Hell, we may not see it be done in our lifetimes or even our grandchildrens, but maybe in a couple of centuries who knows? There has to be alot of development done in ion drive propulsion or the ramjet/scramjet model. Since a huge amount of acceleration is needed to get anywhere near the speed of light.

I once read that even if we built a nuclear powered ship and exploded every single nuclear warhead in existance - to propel itself, we would only acheive 3% the speed of light, which BTW is still a pretty repectable speed. But who really wants to spend a few hundred years getting to the nearest star system?

I would be happy just being around when they launch the first sub-luminar probes to alpha centauri by 2030, which according to Encyclopedia Brittanicas Science yearbooks, will reach speeds of upto 40% the speed of light, using light sails. And lasers to push themselves across space. Mind you they will be the size of several football fields but weigh only a few hundred grams. Most of the area used of course for light sails.

"But in much the same way as breaking the speed of sound was considered last century, so too will breaking the light barrier be deemed impossible for this century."

Actually, the speed of sound was always known to be an engineering problem, not a theoretical barrier and thats a huge difference. It was pretty obvious that bullets were traveling much faster than the speed of sound long before airplanes. So far, all the theory we have tells us that accelerating an object with mass to the speed of light is impossible due to the laws of physics.

There are several technologies being pursued to push the speed of spacecraft up (some that you mentioned). One that still needs a lot of work but has been used in a probe is ion propulsion. Its basically an electron gun like your tv, but without the screen. Since action/reacion propulsion depends on the exit velocity of the propulsor, an electron gun is extremely efficient. Unfortunatly it also produces very little total thrust. The one used in a probe (I think to saturn) will produce thrust equal to the weight of a piece of paper for a number of years straight without refueling.

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Originally posted by Porksoda
I got into an arguement with an old friend in a different forum and I ended up going to one of the heads of theoretical Physics at my University, the University of Michigan. Only a bit of what she said is really applicable here, but here is my 2 cents. She told me that while some particles/waves actually CAN travel faster than light, no information can be transmitted faster than light. Also, she pointed out that theoretical particles know as Tachyons could travel faster than light, but could not travel SLOWER than light. However, these particles as far as we know would not be capable of interacting with our universe so we have no way of proving or disproving their existance.
Also, with regard to changing c. I spoke with another professor and he said that he is not entirely sure if you CAN actually alter c. What he DOES know is that you can pass light through a medium and cause the total travel time to vary, in THEORY changing c. However it is still left to speculation exactly what is happening inside the medium to account for this change. It may be that the light actually is slowing down, OR it could be interacting with the matter and "pausing" as it goes, effectively increasing its travel time, or it could be doing God knows what else...

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It has been proved that c can be decreased. A Danish physicist named Lene Vestergaard Hau once achieved some incredible results, she actually halted a light beam. The experiment is rather advanced to describe in great detail but I´ll try to make it short.

The ingrediens was 11 million sodium atoms which were cooled to 900 billionth of one degree celcius over the absolute freezing point. Under such a temperature the atoms change its state from being particles to an ellipsis shaped superatom with a length of 0,4 millimeter. When this superatom is being hit by a "couplinglaser," the "dark matter" is being created. This state of matter only exists in earthly laboratories. When the testlaser was firing a kilometer long beam of light in the dark matter, the beam of light was frozen inside the dark matter, after they disabled the "couplinglaser."

hey, this is my first time in the "highly technical PC forum here... and this is an amazing topic. i'll enjoy reading this but i doubt i could make a comment ;)

sorry if this is OT or spam, don't reply to this message, and maybe we can keep on topic ;)

i also happened to notice...this thread is VERY long!

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Originally posted by Positron


It has been proved that c can be decreased. A Danish physicist named Lene Vestergaard Hau once achieved some incredible results, she actually halted a light beam. The experiment is rather advanced to describe in great detail but I´ll try to make it short.

The ingrediens was 11 million sodium atoms which were cooled to 900 billionth of one degree celcius over the absolute freezing point. Under such a temperature the atoms change its state from being particles to an ellipsis shaped superatom with a length of 0,4 millimeter. When this superatom is being hit by a "couplinglaser," the "dark matter" is being created. This state of matter only exists in earthly laboratories. When the testlaser was firing a kilometer long beam of light in the dark matter, the beam of light was frozen inside the dark matter, after they disabled the "couplinglaser."

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Sh!t. All I wanted were sharks with frickin' "couplinglasers" on their heads! <G>

Arcadian

Here is an INTRESTING READ Another experiment which stops the light, tells more detials in simple words for ppl like me.

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Sh!t. All I wanted were sharks with frickin' "couplinglasers" on their heads! <G>

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:rolleyes:

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Originally posted by Prince
Here is an INTRESTING READ Another experiment which stops the light, tells more detials in simple words for ppl like me.

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That´s a quite interesting article you provided us - thanks. I´ve always wondered if we could find any beneficial purposes on reduced light speeds in practice.

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Originally posted by Prince
Here is an INTRESTING READ Another experiment which stops the light, tells more detials in simple words for ppl like me.

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There's a similar, but a bit more technical, article about this experiment in this month's Nasa Tech Briefs. (Sorry, no link, the just send me a pdf file every month.)

Getting back to the speed of light discussion, here is an article on time travel and how einsteins theory of relativity helps to explain some of the more modern interpretations/theories of time travel.

http://www.sciam.com/article.cfm?art...FB809EC5880000

A top read, if your into this kind of stuff.

Thanks for the article Gogita. Looks pretty interesting.

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Originally posted by Gogita
Getting back to the speed of light discussion, here is an article on time travel and how einsteins theory of relativity helps to explain some of the more modern interpretations/theories of time travel.

http://www.sciam.com/article.cfm?art...FB809EC5880000

A top read, if your into this kind of stuff.

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Wow, I never knew that gravity was a factor when calculating time travel.

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Originally posted by Gogita
Getting back to the speed of light discussion, here is an article on time travel and how einsteins theory of relativity helps to explain some of the more modern interpretations/theories of time travel.

http://www.sciam.com/article.cfm?art...FB809EC5880000

A top read, if your into this kind of stuff.

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very nice read. thanks for the link.

Yeah, I was so enthralled with that piece that I'm now looking for some of the books mentioned in the biograhpy. So fellas, what are your thoughts?

The one about the black hole and gravity having some influence on time travel got me thinking. Does this mean that if I lived on Mars for 20yrs, that I would experience some noticeable time dilation... since Mars is 1/3 the mass or density of Earth? What about if I lived on a space station orbiting Jupiter (being the largest celestial object after the sun, with considerable gravity to warp space-time) hell what if I skimmed the surface of the sun at a high velocity and returned to earth would I have travelled forwards by maybe even a few hours?

It takes a lot of gravity or a very high speed to get a noticeable time dilation, but it is MEASURABLE on something as simple as a tower (being further from the center of the earth lowers the gravitational influence). That experiment was actually the first evidence to confirm the time dilation effects of relativity, but because of the technology needed for such an accurate clock, it was decades after Einstein published it. I read somewhere that the US astronaut with the most time in orbit has had his age reduced by only a few miliseconds in his many months in orbit. That article mentions that on the surface of a neutron star the time dilation is only 30% - and a neutron star is millions of times denser than the sun.

Also, I don't really consider that time travel, since you can't jump around. Its just messing with the rate of the passage of time. Calling it time travel just conjures up science fiction ideas and the general public already has enough trouble telling the difference between fiction and reality when it comes to science.

If your referring to the hollywood interpretation of time travel, then take a back seat cuz chances are that may never happen.

I dont think you will ever see a flux capacitor running in your Ford or Chrysler, champ. So really to even get anything resembling time travel, I think manipulation or acceleration of the passage of time may be all we can do. And considering how difficult it is... near damn impossible with current technologies... its by no means an easy feat.

I dont expect many people to opt for this form of time travel, but it is still one way of achieving it.

Of course trying to fly into a blackhole and escaping it are very extreme ways of attempting time travel. I am sure that the real key to time travel lies with the understanding of gravity, if we can unveil the mysteries of this force we can probably eventually manipulate it and hence control the rate of the passage of time one would want to achieve. Of course gravity is one of the least understood forces in nature, we don't even know what contitutes it. What particles it is made from or if can be simulated artificially.

What do you think government has in store for us, in terms of time travel? You know they are always at least 50 years ahead of what we can see. I don't want to start or hear rumors, but if someone does have some information that is based on some facts, it will be intresting.

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Originally posted by Prince
What do you think government has in store for us, in terms of time travel? You know they are always at least 50 years ahead of what we can see. I don't want to start or hear rumors, but if someone does have some information that is based on some facts, it will be intresting.

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some very reliable sources have suggested that the government has a working time machine at area 51 which they used to prevent the germans from getting the abomb during ww2.


seriously though i doubt it. any form of hypothetical time travel if possible would require some major breakthroughs in science and engineering. i doubt any government has that much stuff up its sleave. but again, you never know for sure.

"What do you think government has in store for us, in terms of time travel? You know they are always at least 50 years ahead of what we can see."

"some very reliable sources have suggested that the government has a working time machine at area 51 which they used to prevent the germans from getting the abomb during ww2."

Thats just plain silly.


"If your referring to the hollywood interpretation of time travel, then take a back seat cuz chances are that may never happen."

Yeah, Gogita, thats what I was talking about. That kind of time travel gets so much attention in the press that people start to believe it is possible. And I think it will always remain science fiction.

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Originally posted by Prince
What do you think government has in store for us, in terms of time travel? You know they are always at least 50 years ahead of what we can see. I don't want to start or hear rumors, but if someone does have some information that is based on some facts, it will be intresting.

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The (our) government doesn't have any sort of time travel devices. Nothing of the sort in testing or development. I can say this with certainty. My father (20 years in AF) has a top secret clearence.

Time travel is not possible because of the physical limitations of our bodies. Even if our physical limitations were not present I don't think we could do little more than "stretch" time as with slowing it down slightly by avoiding fields of gravity. This wouldn't do much good as I don't think it would be worth the life extension to float around in space for years lol.

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Originally posted by jester22c



The (our) government doesn't have any sort of time travel devices. Nothing of the sort in testing or development. I can say this with certainty. My father (20 years in AF) has a top secret clearence.

Time travel is not possible because of the physical limitations of our bodies. Even if our physical limitations were not present I don't think we could do little more than "stretch" time as with slowing it down slightly by avoiding fields of gravity. This wouldn't do much good as I don't think it would be worth the life extension to float around in space for years lol.

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So what does the government have in store for you?

=edit= Shouldn't put us...not from USA...

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Originally posted by russ_watters
"What do you think government has in store for us, in terms of time travel? You know they are always at least 50 years ahead of what we can see."

"some very reliable sources have suggested that the government has a working time machine at area 51 which they used to prevent the germans from getting the abomb during ww2."

Thats just plain silly.

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it was meant as a joke ;)


personally, i believe it would be arrogant to rule out the possibility of time travel (in it's usual meaning.) now i'm not saying that i believe it is possible but i do keep an open mind. time is not something that we understand very well so i think it's unwise, actually down right arrogant to rule out the possiblity of time travel.

I read somewhere that in WWII, a corspe was found crushed beyond recognition in Nazi controlled Europe. The eerie thing about this, wasn't that it was found lying in the middle of the road from one day to the next but rather, the fact that a mobile device was found on his person. And if I'm not mistaken a few metres a way was crumpled rings of metal, to the trained scientific eye... resembling a mini version of a particle accelerator.

Could this be early tamperings of time travel? In the WWII picture, the caption read. Temporal Cold War - Fact or Fiction? It would seem that a government operative supposedly attempted time travel in order to alter the past, but unfortunately was crushed by what one could imagine, the fantastic gravitational forces in space/time.

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Originally posted by Gogita
Could this be early tamperings of time travel? In the WWII picture, the caption read. Temporal Cold War - Fact or Fiction? It would seem that a government operative supposedly attempted time travel in order to alter the past, but unfortunately was crushed by what one could imagine, the fantastic gravitational forces in space/time.

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heh i'm sure that's just a rumor. well 99% sure.