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Author Topic:   Reaching the practical end of physics?
jar
Member
Posts: 33890
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.8


Message 16 of 68 (437367)
11-29-2007 7:51 PM
Reply to: Message 15 by cavediver
11-29-2007 7:46 PM


Re: On the cusp of knowing nothing at all
Although if you actually read beyond the headline his own links says:

However, Lijun Wang, one of the scientists from the NEC Research Institute in Princeton, N.J., says their findings are not at odds with Einstein.

She says their experiment only disproves the general misconception that nothing can move faster than the speed of light.

The scientific statement "nothing with mass can travel faster than the speed of light" is an entirely different belief, one that has yet to be proven wrong. The NEC experiment caused a pulse of light, a group of waves with no mass, to go faster than light.


Aslan is not a Tame Lion

This message is a reply to:
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EighteenDelta
Inactive Member


Message 17 of 68 (437370)
11-29-2007 7:55 PM
Reply to: Message 14 by Hyroglyphx
11-29-2007 7:12 PM


Re: On the cusp of knowing nothing at all
c=299,792,458 meters per second (1,079,252,848.8 km/h) in an empty vacuum, not in a chilled, super-vacuum injected sodium, nor in a "vapour of laser-irradiated atoms". Even glass will slow light by 2/3. Try again.

Similarly, a joint effort made by the Rowland Institute yielded equally impressive results. This team managed to bring light waves to a one mile per hour crawl and then stopped the beam entirely. They could literally capture, and re-release light, at their whim.

Hmmm can't find anything about 1 mile per hour... they claim "a pokey 38 miles per hour" and nothing about stopping entirely or capture and "re-release at their whim." And WTF is 're-release'? Try again.

-x

Edited by EighteenDelta, : added non-sense


"Debate is an art form. It is about the winning of arguments. It is not about the discovery of truth. There are certain rules and procedures to debate that really have nothing to do with establishing fact — which creationists have mastered. Some of those rules are: never say anything positive about your own position because it can be attacked, but chip away at what appear to be the weaknesses in your opponent's position. They are good at that. I don't think I could beat the creationists at debate. I can tie them. But in courtrooms they are terrible, because in courtrooms you cannot give speeches. In a courtroom you have to answer direct questions about the positive status of your belief. We destroyed them in Arkansas. On the second day of the two-week trial we had our victory party!"
-Stephen Jay Gould

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Hyroglyphx
Inactive Member


Message 18 of 68 (437373)
11-29-2007 8:03 PM
Reply to: Message 15 by cavediver
11-29-2007 7:46 PM


Re: On the cusp of knowing nothing at all
Nem, just as a quick point of information before I go to bed: neither of those experiments have anything to do with demonstrating Einstein incorrect, nor do they in any way put Special or General Relativity in the slighest jeopardy. But of course that's boring, so the reporters have to jazz it up a bit - i.e. get it all totally wrong.

Why not though? If E=mc2 and c being a constant of light traveling in a vacuum, and either of these studies defy that principle, then isn't Einstein's calculations incorrect?

Admittedly I am very much the layman when it comes to the mathematical principles of physics. And there is certainly the possibility that I haven't the sophistication to understand lesser principles that are yet known to me, but this seems pretty straight forward, no?

Why wouldn't either of these experiments challenge Special Relativity?


“This life’s dim windows of the soul, distorts the heavens from pole to pole, and goads you to believe a lie, when you see with and not through the eye.” -William Blake

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cavediver
Member (Idle past 2875 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 19 of 68 (437374)
11-29-2007 8:11 PM
Reply to: Message 16 by jar
11-29-2007 7:51 PM


Re: On the cusp of knowing nothing at all
Yeah, I saw that afterwards... sadly, if anything, it makes things worse :)

The scientific statement "nothing with mass can travel faster than the speed of light" is an entirely different belief, one that has yet to be proven wrong. The NEC experiment caused a pulse of light, a group of waves with no mass, to go faster than light.

Light itself has no mass - it's famous for it :) And the waves didn't go faster than light. The varying position of a peak within the wave may have appeared to travel faster than light, but that is akin to sweeping a torch around your head and claiming that the beam just went around the universe in a matter of seconds...


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jar
Member
Posts: 33890
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.8


Message 20 of 68 (437375)
11-29-2007 8:17 PM
Reply to: Message 19 by cavediver
11-29-2007 8:11 PM


Re: On the cusp of knowing nothing at all
Yeah. IIRC we have had a few threads about the experiment over the years. I'll see if I can dredge one of them up. I think Silas had a great post on it.


Aslan is not a Tame Lion

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Hyroglyphx
Inactive Member


Message 21 of 68 (437377)
11-29-2007 8:19 PM
Reply to: Message 17 by EighteenDelta
11-29-2007 7:55 PM


Re: On the cusp of knowing nothing at all
c=299,792,458 meters per second (1,079,252,848.8 km/h) in an empty vacuum, not in a chilled, super-vacuum injected sodium, nor in a "vapour of laser-irradiated atoms". Even glass will slow light by 2/3. Try again.

What difference is there, other than perhaps large quantities of sodium particles, than space?

Hmmm can't find anything about 1 mile per hour... they claim "a pokey 38 miles per hour" and nothing about stopping entirely or capture and "re-release at their whim."

That's because that article is basically an abstract.

"In 1999, Danish physicist Lene Vestergaard Hau led a team from Harvard University who succeeded in slowing a beam of light to about 17 metres per second and, in 2001, was able to momentarily stop a beam. She was able to achieve this by using a superfluid. Hau and her associates at Harvard University have since successfully transformed light into matter and back into light using Bose-Einstein condensates. Details of the experiment are discussed in an article in the journal Nature, 8 February 2007.

And WTF is 're-release'?

Light is released, then stopped, then re-released.


“This life’s dim windows of the soul, distorts the heavens from pole to pole, and goads you to believe a lie, when you see with and not through the eye.” -William Blake

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cavediver
Member (Idle past 2875 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 22 of 68 (437378)
11-29-2007 8:23 PM
Reply to: Message 18 by Hyroglyphx
11-29-2007 8:03 PM


Re: On the cusp of knowing nothing at all
If E=mc2 and c being a constant of light traveling in a vacuum, and either of these studies defy that principle, th en isn't Einstein's calculations incorrect?

Yes, if they defy that principle... but they don't. Neither experiment takes place in vacuum, and they depend upon their respective specialised media for the effects in question. Slowing light is a doddle - it takes a 'photon' some 50,000 years (or something equally ridiculous) from generation at the centre of the Sun to finally reaching the surface!

The speeding up is an optical illusion. Say I have a wave with mid-point at A with a peak at the back (left) end. This wave travels at near-c (left-to-right) from A to B. By the time its midpoint is at B, by some properties of the medium, the peak is now at the front (right) end. So in the time in takes the wave to travel from A to B, the peak appears to travel from left of A to right of B - and so has travelled (further in the same time and so) faster than light! But the peak isn't a 'thing' - it is just a property of the wave. Any data encoded in the peak while at A will not be in the peak at B, but smeared across the whole wave. So the data still travels at c.

Edited by cavediver, : Added some left and rights to hopefully make it slightly less confusing


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Replies to this message:
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AnswersInGenitals
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Posts: 653
Joined: 07-20-2006
Member Rating: 3.5


Message 23 of 68 (437431)
11-30-2007 1:40 AM
Reply to: Message 18 by Hyroglyphx
11-29-2007 8:03 PM


A cut above (the speed of light).
NJ: You can get some idea of what is going on by taking a scissors and slowly closing them by moving the handle parts together. The point where the two blades intersect will move much faster than the handles or the blades themselves. But that intersection point is not a real 'thing'. If you unscrew the two halves of the scissors so that the blades aren't even touching you can still get the intersection to move a much greater speed than the blades themselves. If the blades are very nearly parallel you might actually get the intersection to move faster than the speed of light. But that intersection cannot carry any information or push any matter along with it without imposing a great deal of force on the blades. If you get the blades nearly parallel and try to squeeze any object along the intersection, as the intersection approaches the speed of light the forces imposed by that object will approach infinity.

What the quoted researchers did was to take a medium in which light of different frequencies travel at different speeds (referred to as a dispersive medium because in the shape of a prism it will disperse the light of different frequencies in different directions and spread them out) and send in a few light beams of different frequencies. Now, think of these light beams in the shape of undulatory waves with their slightly different wave lengths moving at slightly different speeds. The point where they intersect and add up can, with proper adjustment of parameters, move much faster than the individual waves themselves, just like the blades of the scissors. This is called the phase velocity of the group of waves. No matter or information can be pushed along at this intersection at the phase velocity. It is really, more than anything else, just a mathematical apparition. As has been said, nothing in these experiments violates Einstein's theory of relativity. In fact, there has been no repeatable experiment to date that violates Einsteinian relativity. By the way, the principles and mathematics involved in these experiments is pretty much college freshman level. It is the experimental details of creating the dispersive medium and the various light wave packets that makes these experiments so challenging.


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Percy
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Posts: 20749
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.2


Message 24 of 68 (437459)
11-30-2007 7:51 AM
Reply to: Message 18 by Hyroglyphx
11-29-2007 8:03 PM


Re: On the cusp of knowing nothing at all
NJ writes:

Why not though? If E=mc2 and c being a constant of light traveling in a vacuum, and either of these studies defy that principle, then isn't Einstein's calculations incorrect?

A couple people have already pointed out that c is the speed of light in a vacuum, not the speed of light in the medium in which your experiment takes place. It's an inherent property of our universe. For example, it doesn't vary if you're working with prisms where light travels more slowly.

Another way to think about c is that it is the maximum speed of influence, i.e., the maximum speed at which one part of the universe can affect another. For example, the influence of gravity travels at c. Light traveling unimpeded in a vacuum is just a convenient way of measuring c.

--Percy


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Hyroglyphx
Inactive Member


Message 25 of 68 (437517)
11-30-2007 11:35 AM
Reply to: Message 22 by cavediver
11-29-2007 8:23 PM


Re: On the cusp of knowing nothing at all
Yes, if they defy that principle... but they don't. Neither experiment takes place in vacuum, and they depend upon their respective specialised media for the effects in question.

I thought the point of the endeavor was to in fact either slow or speed light within a vacuum, as in, they recreated a model that would resemble such conditions.


“This life’s dim windows of the soul, distorts the heavens from pole to pole, and goads you to believe a lie, when you see with and not through the eye.” -William Blake

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Wounded King
Member (Idle past 3327 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 26 of 68 (437532)
11-30-2007 12:31 PM
Reply to: Message 25 by Hyroglyphx
11-30-2007 11:35 AM


Re: On the cusp of knowing nothing at all
What they created doesn't sound much like a vacuum to me.

There is theoretical support for the idea that c can be exceeded by light in the extra rarefied vacuum between plates exhibiting casimir effect behaviour.

TTFN,

WK


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cavediver
Member (Idle past 2875 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 27 of 68 (437538)
11-30-2007 12:57 PM
Reply to: Message 25 by Hyroglyphx
11-30-2007 11:35 AM


Re: On the cusp of knowing nothing at all
I thought the point of the endeavor was to in fact either slow or speed light within a vacuum, as in, they recreated a model that would resemble such conditions.

That's certainly the impression given by some of the reports on those experiements - by general media and popular scientifc press alike - but such impressions are very wrong. It is sad but true that most of the science you read about in the press will be so distorted that you will be left with completely the wrong idea; this seems especially true in quantum/theoretical/cosmological matters, though that could of course be just my own selection effect/bias.


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Hyroglyphx
Inactive Member


Message 28 of 68 (437541)
11-30-2007 1:12 PM
Reply to: Message 26 by Wounded King
11-30-2007 12:31 PM


Re: On the cusp of knowing nothing at all
What they created doesn't sound much like a vacuum to me.

There is theoretical support for the idea that c can be exceeded by light in the extra rarefied vacuum between plates exhibiting casimir effect behaviour.

Whatever the case the may be, I am simply in disagreement with H about the end of physics. Einstein challenged Newtons classical mechanisms. Galileo challenged Coperinicism. Darwin challenged Lamarck. The point is, somebody will always be there to challenge a paradigm.

I think it would be foolhardy to assume that we can sort of max out in the realm of physics. I mean, isn't the slit experiment just the tip of the iceberg when it comes to quantum physics?


“This life’s dim windows of the soul, distorts the heavens from pole to pole, and goads you to believe a lie, when you see with and not through the eye.” -William Blake

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crashfrog
Member (Idle past 699 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 29 of 68 (437544)
11-30-2007 1:26 PM
Reply to: Message 28 by Hyroglyphx
11-30-2007 1:12 PM


Re: On the cusp of knowing nothing at all
I think it would be foolhardy to assume that we can sort of max out in the realm of physics.

I'm very much in agreement with that. It's rather ridiculous to assert that we're at the end of physics when we still haven't convincingly figured out how quantum mechanics and general relativity actually operate in the same universe.


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Silent H
Member (Idle past 5051 days)
Posts: 7405
From: satellite of love
Joined: 12-11-2002


Message 30 of 68 (437552)
11-30-2007 1:51 PM
Reply to: Message 28 by Hyroglyphx
11-30-2007 1:12 PM


Re: On the cusp of knowing nothing at all
I am simply in disagreement with H about the end of physics.

Ahhhhh, you're not in disagreement. I wasn't stating we had reached the end (me with sandwich-board "end is nigh!"). I was asking a question to push answers.

I do wonder if there is a limit of human capability, or even inherent practical limits. There are still plenty of things for Physicists to look at and play with. As I stated earlier gravity is still relatively unknown, antimatter is simply unwieldly at this point in time (but who knows for later), and quantum effects are clearly exploitable.

Where I was specifically pointing was within a section of physics... particle physics... at the search for smaller and smaller bits and how they operate. With the great deal of energy, and the extremely short times they can exist... and they seem to fall back together into what we have to deal with on a daily basis, could we be hitting a practical wall on that end?

But I think everyone has been pitching in responses that explain where some value can be obtained. And actually I hadn't known of how NMR was originally tested, which seems like an even better parallel (for a practical answer to my question) than analogies to the state of general knowledge regarding the atom circa 1900.

Whether you got the speed of light thing right or not, I do appreciate the references. I hadn't heard of one of them and it was fascinating, even if not Einstein-breaking.


h
"Civilized men are more discourteous than savages because they know they can be impolite without having their skulls split, as a general thing." - Robert E. Howard

This message is a reply to:
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Replies to this message:
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