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Physicists Clarify Exotic Force
Azazel writes "A research group, including Purdue University physicist Ephraim Fischbach, has completed an experiment which shows that gravity behaves exactly as Isaac Newton predicted, even at small scales. Unfortunately for those in search of the so-called "Theory of Everything," the finding would seem to rule out the exceptions to his time-honored theories that physicists believe might occur when objects are tiny enough."
Well, this is the first time I've heard of the "Casimir force" force, but reading the article linked to in the article (how's that for RTFM) explains that pretty well. Now, the prevailing "ToE" is to the best of my knowledge, string theory. This theory was developed to explain the inconsistancies with Newton's and Einstein's laws when you got down to a sub-atomic level. This study is basically saying that string theory is wrong, and that Newton and Einstein (for the most part) were right.
Now, the interesting there here is the "Casimir force" which basically, is the force of photons striking an object. We touched on this actually in high school physics. We were experimenting to find out if light was a wave of a particle. (its a wave of particles). I started to ask questions like, if that's true, wouldn't most stationary objects eventually gain mass due to a build up of photons. We never quite got into that... probably a little advanced for most people in high school physics. Sorry, back on topic. This force, becomes very powerful (comparatively) at sub-atomic levels. The force of a particle travelling at the speed of light can become very significant. In fact, it becomes more significant than gravity. So, everything as usualy, I'm not sure I'd agree, but it hopefully does get us one step closer to the ToE.
Particle/wave duality is not fully explained by thinking of light as a wave of particles, as this conflicts with observations of diffraction gratings at extremely low light intensities. It is my understanding that a "refinement" is to describe light as a single photon that exists with varying probabilities across the wave. (The wave is then a probability wave.)
QM allows objects to exist at multiple points or in multiple states simultaneously, until directly observed. If you do try to directly observe a photon, you do indeed see a single packet of energy. But if you look only at the results, you see a wave.
By looking at light as a probability wave, a lot of apparent paradoxes don't "go away" but do fit a lot better with other known apparent paradoxes, which (to me) indicates the phenomena are related and not distinct.
Getting back to gravity, we could be in for an interesting dilema here. With no variations so far detected, the theory of gravity being an exchange of particles seems less likely. Einstein's model of a distorted space/time would seem to be the more probable, at this point.
This is important, as the predicted QM model for gravity could not be compatible with Enstein's model of gravity. They could not coexist, one had to be wrong. At this point, it seems likely that the particle-exchange model is the one that is wrong, which means QM in its eventual form will likely not be 100% particle based. It may need to be a heterogenius model.
As an aside, let us assume gravity does bend space/time. Since information cannot travel infinitely fast, and as no two events can occur simultaneously, when a massive object moves, space cannot restore itself the moment the object has left. Thus, there must be something analogous to a restoring force within space/time, and therefore some parallel to Hooke's Law.
By implication, an object moving fast enough should leave a trail, where the effect of gravity on space/time is apparent, even though there is no longer any source of that gravity present. A massive-enough object may even leave some sort of "wake", similar to that of a boat, only in gravity rather than in water.
Hooke predicts an upper limit to expansion, though. Something stretched beyond a certain point cannot be restored to its original dimensions, but will rather be restored to some other state, with a much lower restoring force existing.
By implication, a sufficiently massive black hole should result in a region of permanently deformed space/time, as the expansion would exceed the Universe's ability to restore.
As far as I know, no such "massless holes" have been found, but the more the Einstinian model is verified, the more certain I am that such a thing must exist.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Sometimes science can get a little too compartmentalized. the vdW force is more in the domain of chemists than of physicists so physicists don't get taught it.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Slightly off-topic:
So they still haven't observed the graviton and are still having trouble explaining why.
What I'd like to know is, why aren't physicists trying harder to explain gravity as a "pseudo-force" like the centrifugal "force" and the Coriolis effect? That's not just a rhetorical question. What makes physicists so sure that the graviton even exists? I trust that there must be some deep reasoning involved -- what is it?
"BTW, what moderator decided that this comment was "Interesting"?"
What deity bestowed the ultimate truth and power to judge the value of opinions upon you? I found the comment interesting. This is a great forum for discussion of news items, and that is what I come here for.
What I wouldn't give for a "-5, Callous Pedantism" mod.
Now onto the rest of my post: The physicists at Warwick University, for the Einstein Celebration, considered my theories on relativity to actually be pretty good. :) I had produced a summary of the derivation of relativity and from that derived what overall physical phenomena must underpin the entire theory.
The quantization of space/time is guaranteed. Why? Because matter is quantized, and matter and energy are simply different facets of the same thing, energy must be quantized. (Matter is merely condensed energy, it is therefore the same stuff, just in a different state.)
If energy is quantized, then fields must be quantized, as fields define energy. If fields are quantized, then space and time are quantized, as fields are defined over these.
The scale of quantization is extremely small. A Higg's Particle is the smallest unit of matter definable, but in order to have energy to condense, the scale on which a photon itself exists must be smaller still. There may well be smaller particles in the "quantum foam", which is fine as they don't have to be stable. The Higg's Particle is stable and is likely the smallest object that can be stable.
What does that give us for scale, though? Without knowing even the theoretical mass of the Higg's Particle, that is hard to even guess at, but a guesstimate based on existing data would imply quantization of space at around about 10^-50 m, and something comparable for time.
No, you do not perceive gravity as a point source, because you are not a point. That is why objects in a gravity well will stretch. EACH point of you will experience gravity differently and not from "one source" but rather from the composite value.
(If you are between Earth and the moon, you will experience gravity from each. At the right point, you will be held stationary because the interference will produce no net force. If that were not the case, the Universe would be in serious trouble. As would most of physics, as a lot depends on overlapping fields.)
We are talking about energy differentials. It is a grave mistake of the first order to distinguish between phenomena that are, in fact, the same thing. All objects travel at the speed of light, at different angles to space/time. It is the angle that produces relativistic mass, reliativistic length and relativistic time.
This can be proved by simple trigonometry, and is likely where Einstein got the equations in the first place. Relativity is just a restating of Pythagoras, as all equations are based on the same formula: R' = sqrt(1 - v^2/c^2), where R' is the relativistic version of the variable of interest.
When re-written, this becomes R'^2 + V^2 = C^2, which is basically Pythagoras.
However, the consequence of this is both simple and profound. If all objects indeed travel at the speed of light, at different angles to space/time, and indeed relativity is nothing more than the projection onto the plane of interest, then gravity is a direct consequence of this motion through space/time.
(Relativistic mass, by this logic, is simply a force exerted at 90' to space. The distortion of space is the result of this. This means tha
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Nobody has ever adequately explained to me why string theory is popular. It isn't actually a "theory", since it hasn't made any testable predictions. There is no problem which it has (yet) solved. Its desirable features (e.g. supersymmetry) are not known to be useful in the first place. Even its motivating examples don't seem to fit the theory. (Hadrons look like strings, but no known string models look anything like hadrons.)
As far as I can tell, the argument seems to be that high-energy physicists need to be doing something other than sitting around twiddling their thumbs, and until someone comes up with an alternative, string theory is that something.
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Hmmm... just finished reading an excellent book about cosmology (The Fabric of the Cosmos, by Brian Greene). In it, the author clearly states that all objects are constantly moving at the speed of light through space-time.
If you are stationary in space, then you are "moving" at the speed of light through time. Any motion through space reduces your velocity through time - but it always adds up to the speed of light.
I must admit, that idea made me stop and re-read that section of the book a couple of times, as I'd never heard relativity expressed that way before. I may have not entirely presented his arguments correctly (I am not a physicist), but that was the essence of it.
Nope. The only gravity you notice in everyday life is from the Earth, with the Moon and Sun causing tides but not otherwise making any noticable difference. All these things are huge, and their centres (where the net total of all their gravity comes from) are far away. Gravity from nearby stuff is pretty insignificant - you can go next to 10000 kilograms of lead and you don't end up standing at a weird angle (although a sensitive scientific instrument can measure the gravity from that much mass fairly easily, it was done over 100 years ago IIRC).
Anything less than 5mm away has to be tiny, only a few cubic mm, and therefore with virtually no mass or associated gravity. So a human certainly wouldn't ever notice.
Photons have no rest mass. Rest mass is the magnitude or length of the energy-momentum pseudotensor. Whether it has mass depends on how you define mass. If you use a semi-classical definition of mass as that which resists motion and creates gravity, then mass is energy, which photons have. But a lot of physicists use mass to mean rest mass, which is 0 for a photon. If you try to decelerate a photon, it keeps moving at c, but it decreases in frequency. If you try to bring it to a rest, you will red-shift it into oblivion.