very interesting discussion

[metiz]

You're on the sun and the sun explodes. That is bad news so you want to warn the people on earth and you have a theoreticall 8 something minutes to do so before the effects reach earth (speed of light). Luckily, you already have a pencil, stretching some 160.000.000km, placed on the earth with the other end in your hand. you write the warning an the earth is saved -right? BUT that would mean information has traveled faster the light.. or has it?

http://www.centerforinquiry.net/forums/ ... d/3163/P0/

[Mike Everman]

Their conversation was silly, but superluminal events are fun to think about. A better example is a pair of scissors, which have blades that are very close to parallel. When you make the "cut", the crossing point of the blades can go faster than light. Is it information? Certainly it's no physical thing that has gone super luminal...

[metiz]

for the siccor (spelling) you have a leaver. to operate said leaver so that the tips travel faster then the speed of light, you'd need an infinite amount of force to push the handles together, wich is impossible. the pencil thing is (more or less) something different. It might be a childish example but the discussion has yet to be settled and there are quit a few people in the discussion who seem to know quite a bit about the subject.

[Mike Everman]

I'll go back and check it out. Read my post carefully, I did not mention the tips. It's a fascinating example.

[larry cottrill]

The long pencil is not massless and is not perfectly rigid. Your hand motion at one end of the pencil will be communicated as a wave from one end of the pencil to the other. The speed of the wave will be determined by the mass per unit length of the pencil and its elastic properties, which will approximate the properties of plain wood. I would guess that the wave travel would approximate the speed of sound in wood. At any rate, it would certainly not come even remotely close to light speed.

The same flaw applies to the long scissors. The crossing point moving back and forth as they are opened and closed certainly constitutes information transfer. However, the problem is, again, that very long scissors are not truly rigid objects. When you attempt to "close" the scissors by pressing the handles toward one another, this initiates a wave in each of the two sections that works to bring them together. The wave, however, can only travel down the scissors at a speed constrained by the mass per unit length and the elasticity of whatever steel the device is made from. The actual point of closure will only travel down the length of the blades at approximately this wave speed. Again, I suspect that this speed approximates the speed of sound in the steel, at whatever temperature you have at a given point along the length.

The big error in these thought experiments is the assumption that physical things behave as "rigid bodies". There is no such thing as a truly rigid body, as every structural engineer or acoustic engineer knows. To a practicing engineer, every science textbook author sounds like an idiot, because they seem to know absolutely nothing about real properties of real materials. Of course, they would say that they're operating under a set of "simplifying assumptions", one of which is that solid materials are "rigid". There are many, many more such assumptions, all of which work to make the universe seemingly comprehensible on the two-dimensional surface of a book page. But that is an illusion.

How many times have you read that the Doppler red shift of the outer galaxies shows that the universe is expanding? Yet, almost in the same breath, the author says that because of the speed of light, we are seeing these galaxies as they were thousands or millions of years ago! How then can he claim that the expansion is known to be happening? Even ASSUMING that the red shift really means that (i.e. there is no "tired light" effect), the best you can say is that the universe WAS apparently expanding thousands (or millions) of years ago. If the universe then began collapsing in on itself, how would we know? What "faster than light" information from the galaxies would warn us? Such is the silliness of textbook pronouncements of things that can't possibly be verified by any available process.

In the case of the scissors, as the blades come together, it can be demonstrated that the angle subtended by the cutting edges would actually be less acute (at a given distance from the hub) than would be predicted by the geometry of the scissor blades taken as rigid objects, because of the elastic bending as the wave progresses. This angular "error" would be very small of course, because of the high modulus of elasticity of steel. You can approximately visualize the action by imagining two whips with handles held close together being snapped toward each other in "scissors" fashion. The traveling wave that brings them across each other is a vastly exaggerated picture of the edges of two monstrously long scissor blades.

L Cottrill

[Mike Everman]

Thought experiments like this are no fun when you start applying the limitations of real materials and distances. The scissors needn't be very long, they must have flat edges and the pivot be substantially coincident with both edges, but whatever, I grow weary of that one... ha Ultimately the exercise is to take us to more heady stuff, right?

How many times have you read that the Doppler red shift of the outer galaxies shows that the universe is expanding? Yet, almost in the same breath, the author says that because of the speed of light, we are seeing these galaxies as they were thousands or millions of years ago! How then can he claim that the expansion is known to be happening? Even ASSUMING that the red shift really means that (i.e. there is no "tired light" effect), the best you can say is that the universe WAS apparently expanding thousands (or millions) of years ago. If the universe then began collapsing in on itself, how would we know? What "faster than light" information from the galaxies would warn us? Such is the silliness of textbook pronouncements of things that can't possibly be verified by any available process.

Hear, hear, Larry. One of my favorite things is armchair astrophysics! You are absolutely right, "expansion" is merely a convenient term, ultimately, since the universe cannot change size. I have a problem with academia's dogged preaching of Big Bang theory because of the apparent expansion, and the requirement for dark matter because the expansion MUST REVERSE someday. What complete and utter horse crap.
My pet theory is that there really is tired light, though They'll tell you it was "discounted early".

There are two factors:
1. "The roller coaster that gets more spiky as you ride it" Photons from distant galaxies cross many, many gravity wells on their way to us, which wouldn't bother them if the wells were unchanging, but we're talking huge distances and time periods in the crossing. The thing I've not seen considered is that galactic gravity wells deepen with time, as the galaxies sweep all the intergalactic flotsam into themselves. This happens at all scales. Photons MUST lose energy in the crossing.
2. Gravitational redshift (General relativity). Ask yourself: what does a photon know of the Universe? It knows nothing of, and can't be affected by anything ahead of it in it's path. Actually, the universe to it is a cone expanding to the rear as it travels, and therefore gravitational forces on the photon do not balance, they are always "dragging it back".

My favorite axioms:
Whenever we think we can see the extent of the universe, we are wrong.
Trying to infer the beginning of the Universe from what we can see and what we know now is pure folly.
Assuming everything has a beginning and an end is a limitation of the culture of man.

[larry cottrill]

Hear, hear, Larry. One of my favorite things is armchair astrophysics! You are absolutely right, "expansion" is merely a convenient term, ultimately, since the universe cannot change size. I have a problem with academia's dogged preaching of Big Bang theory because of the apparent expansion, and the requirement for dark matter because the expansion MUST REVERSE someday. What complete and utter horse crap.
My pet theory is that there really is tired light, though They'll tell you it was "discounted early".

I agree exactly. How scientists think is sometimes hilarious. The Ether Theory is discarded because the ether is by its very nature undetectable, and then it was quickly declared "unnecessary" -- so-called "ether waves" (now generally called electromagnetic radiation) just don't need a medium to move through. Yet, all other wave phenomena require media to determine things like wave speed and intensity, etc. Now, dark matter is accepted, even though it is undetectable, because it is "necessary" to satisfy a different theory which we so far have no way of validating. An "advanced alien civilization" would find this kind of reasoning utterly laughable. Just wait till somebody decides that dark matter is the medium which determines how electromagnetic waves propagate -- the circle will be complete. Ha. Remember, you heard it here first.

When a really good theory, like General Relativity, is advanced, it only takes about one generation of experimental work (usually a handful of experiments / observations) to "establish" it. After that, no one ever questions the original premise, and everything that is done from there on is based on the assumption of its correctness. Alternative explanations that produce the same results will never be considered, ever again, except by people who are willing to be villified as "heretics". Quarks from the Big Bang or splinters from the True Cross -- one relic is about as meaningful as the other.

My favorite axioms:
Whenever we think we can see the extent of the universe, we are wrong.
Trying to infer the beginning of the Universe from what we can see and what we know now is pure folly.
Assuming everything has a beginning and an end is a limitation of the culture of man.

Add this one:
The closer you look at the universe, the more complex it appears. This is fascinating because it is so counterintuitive. When I was a kid, everything was made up of protons, electrons and neutrons, which were irreducibly simple. By the time I got to college, there were dozens more. Then, two or three "quarks" were found, and physicists breathed a sigh of relief that they were able to "simplify" everything again. Does that simplicity still reign? Another example is living cells. When I was a lad, they were the simplest forms of life -- their internal structure was extremely simple and well-described. Today, the cell is seen as an object of almost unbelievable complexity. Refined analysis does not simplify our knowledge of the nature of things, but rather, complicates it.

L Cottrill

[Mike Everman]

Ha ha, so we're back to "how many angels can dance on the head of a pin held in the hand of an angel dancing on the head of a pin" and so on.

[larry cottrill]

Ha ha, so we're back to "how many angels can dance on the head of a pin held in the hand of an angel dancing on the head of a pin" and so on.

They say that fleas have other fleas
Upon their backs to bite 'em.
And these small fleas have smaller fleas
And so, ad infinitum.
- Unknown

L Cottrill

[PyroJoe]

Mike Everman wrote:

"Photons MUST lose energy in the crossing."

Most gravity wells are abundant in photon pressure. In the vast spans between gravity wells are the deserts that have wound down to near nothing.

Joe

[metiz]

They say that fleas have other fleas
Upon their backs to bite 'em.
And these small fleas have smaller fleas
And so, ad infinitum.
- Unknown

The more you think about it, the smaller the particles get and the more questions you get when you solve something, the more it appears the universe is a hologram where every part has all the information of the whole. read: infinitly small particles. This would also mean that NOTHING is real, everything that you percieve or create - it's all an illusion, nothing but energy and frankly, that scares me.

The long pencil is not massless and is not perfectly rigid. Your hand motion at one end of the pencil will be communicated as a wave from one end of the pencil to the other. The speed of the wave will be determined by the mass per unit length of the pencil and its elastic properties, which will approximate the properties of plain wood. I would guess that the wave travel would approximate the speed of sound in wood. At any rate, it would certainly not come even remotely close to light speed.

This has already been discussed heavily but the verdict is still out on that:

from the forum, author "narwhol"

This is incorrect, the movement of all points along the pencil would (more or less) simultaneously since the electrostatic attraction exchange particles are gamma photons generated as one charge moves within the field of another. since the particles at your end are moveing, they move their neighbouring particles by means of exchange gamma photons travelling between them. However, those particles are also moving relative to their nearest and are generating exchenge particles with them almost simultaneously. The generating pairs will altenate along the length of the pencil simultaneously rather than sequentially because when a pair is repelling, the individual atoms that make up this system may be either attracting or repelling a neighbour on a different face. So, yes George, in theory you could communicate faster than light in this way.

Incidentally some people think tacheons travel faster than light, but they tend to be people who think tacheons actually exist, whereupon I don’t have much time (no pun intended) for them.

"narwhol" I mean, he's a physicist, gots to believe him right?

Sorry to pull rank, but I am a physicist. You seem to be labouring undera delusion about the way materials are held together. They are mostly empty space, interspersed with particles. nucleus, which is tiny, is made of up and down quarks held together by the strong electromagnetic force in the form of gluons. This has an overall positive charge. Outside that, you have a comparatively vast empty space in which there are probabilistic density functions of electrons (a “particle” of the lepton family). The nucleus and the electrons attract each other when they move (and therefore cut flux) within each other’s fields. This generates a photon (electromagnetic “particle") of gamma frequency that transmits energy corresponding in quantity to the work done by the field. Outside of these atoms there are other atoms. These have instantaneous pockets of local disproportionate charge density distributed over their “surfaces” that change as their electron density translocates. When the charges of these two instantaneously charges atoms move relative to each other within each other’s fields (thereby cutting flux lines), this generates an electromagnetic “particle”, a photon of gamma frequency and energy equal to the work done by or against the field depending upon whether the charge density pockets are of like or unlike polarities. You seem to thinnk that a photon has to travel the whole length of the pencil in order to transmit the work George does on his end (of the pencil!) to the tip. This doesn’t happen. Photons are transmitting forces between all pairs of neighbouring atoms throughout the pencil all of the time. There is no step-wise generation of photons effect that needs to take time to travel down the length of the pencil, and there is no wave that travels the length of the pencil other than flexural effects of wobble (only of significant amplitude around the middle sections of the pencil anyway) that would have no bearing on the speed of writing the message anyway, but may make George’s handwriting a little bit more untidy. The flexural strength of the material would have no bearing on the speed of communication of the message.

source: centerforinquiry.net

[larry cottrill]

This would also mean that NOTHING is real,

Consider this very carefully. You will find that it does NOT mean that nothing is real. It only means that reality is not what we perceive it to be, because of where our physical senses are placed in the scale of things. If our eyes were as "wide spectrum" as our ears (i.e. covering several octaves), we could see atoms the way we hear the highest notes of a pipe organ. But it's not laid out that way. If our ears were as narrowly tuned as our eyes, we would not hear much of the audio spectrum, yet we could distinguish the tiniest alterations in frequency within that limited range, the way we see the different shadings on the skin of a "red" apple.

everything that you percieve or create - it's all an illusion, nothing but energy and frankly, that scares me.

Per the above, it is not the THINGS that are the illusion -- it is the NATURE of things that is. Think about it: How many "scientific instruments" has man invented since the Middle Ages? Almost every one of those has the basic purpose of allowing us to get closer to reality than our senses alone can take us.

"narwhol" I mean, he's a physicist, gots to believe him right? :)

You seem to think that a photon has to travel the whole length of the pencil in order to transmit the work George does on his end (of the pencil!) to the tip. This doesn’t happen. Photons are transmitting forces between all pairs of neighbouring atoms throughout the pencil all of the time. There is no step-wise generation of photons effect that needs to take time to travel down the length of the pencil, and there is no wave that travels the length of the pencil other than flexural effects of wobble (only of significant amplitude around the middle sections of the pencil anyway) that would have no bearing on the speed of writing the message anyway, but may make George’s handwriting a little bit more untidy. The flexural strength of the material would have no bearing on the speed of communication of the message.

It seems to me utterly absurd to hold with General Relativity and then believe that something at A influences something at B "simultaneously". That is physically equivalent to believing in "action at a distance". He says:

You seem to be labouring under a delusion about the way materials are held together.

That might be true, but HE is laboring under the delusion that he understands how materials behave. The wave action in solid materials is fully known and can be described with considerable precision, especially if the geometry and the material properties are well defined. Check out this small wind-driven example of wave action in solid steel, albeit unanticipated, from away back in 1940:
http://www.youtube.com/watch?v=HxTZ446tbzE

This is why you don't hire a physicist to design a building for you. It would either collapse in a wind storm, collapse under snow load, collapse under seismic action during an earthquake, OR be so expensive that no one could ever afford to build it. Save your neck AND your wallet -- hire a registered Professional Engineer and get something that works. (Of course, we can see that engineers weren't as good in 1940 as they are now -- but note that the bridge that replaced this one has not suffered the same fate. We can all learn from experience! ;-)

A similar argument (from a more "classical physics" perspective) is the following: A piping system is filled with water and contains no air at all. The water is essentially "incompressible". Suddenly, city water pressure is applied at one end, and the other end appears to IMMEDIATELY eject water. (Again, a mechanism that theoretically could be used to send messages. Ha.) But, in reality, there is a delay -- the pressure travels as a wave from one end of the pipe to the other. The delay is just too small for ordinary perception to handle; probably a millisecond or something. The "incompressibility" of the water is a false premise, if you look closely enough. It's hard to appreciate how little movement of the wave medium there has to be to communicate the pressure, on the order of millionths of an inch at any point in the line. Yet, the travel time is there, and amounts to the speed of sound in water at a particular temperature.

L Cottrill

[metiz]

Mr Cottrill,

That is about as far as I can go on this subject. I can't realy put any other arguments in there that would help solve this, however,

It seems to me utterly absurd to hold with General Relativity and then believe that something at A influences something at B "simultaneously". That is physically equivalent to believing in "action at a distance".

you did not acount for quantum entanglement where you can have 2 particles half a universe appart from each other and they will still react to each other simultaniously. Everything in the universe was entangled at the moment of the big bang so everything is entangled now. This means that everything we do has an instand reaction on everything else (in a sense). This would (unfortunately) be much easier to explain if you percieve the universe as a hologram where an entangled (I hate that word ) particle would be just a different perspective on the original.

[Ghrey]

Ok, I'm doing this just because I can.

And because I think some of you might be up to the puzzle.

I posted this on my sight years ago;

So far no GOOD answers.
http://www.ghrey.com/Rants/Photons.html


Another thought I had some time ago

G=∆T ( I do not like it, it ruins physics, But I can not disprove it )

Yes I own stock in a company that makes a headache remedy.

Cheers

[tufty]

Ha ha, so we're back to "how many angels can dance on the head of a pin held in the hand of an angel dancing on the head of a pin" and so on.

They say that fleas have other fleas
Upon their backs to bite 'em.
And these small fleas have smaller fleas
And so, ad infinitum.
- Unknown

L Cottrill

Jonathan Swift, actually (and then parodied in the other direction by Augustus de Morgan), although the formulation above is a misquote, so I suppose "Unknown" is almost correct. The original is as follows:

So, naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite 'em,
And so proceed ad infinitum.
Thus every poet in his kind
Is bit by him that comes behind.