Friar Bellows

Do you have a reference or three about this? I never came across "gravitons" in my undergraduate studies of quantum mechanics. I always thought they belonged to the domain of string theory, which I never got to study (we barely touched on Dirac's relativistic QM theory, let alone quantum field theory, let alone string theory).

raindropple

Thank You for all the information.

Though it still seems science has no answers as to why.

Though quite good research was done as how things are working, basically monitoring and checking and trying to explain results by drawing some conclusions.

So will I be right if I say that science today dont really answer the interesting questions?

Friar Bellows

Special relativity couldn't care less about the photon's rest mass. What I mean is, if it turns out that the photon does have a small rest mass, then in the second (light) postulate we could change the phrase, "the speed of light", to "the speed of a massless particle", and then all the results of special relativity would remain the same. One can teach special relativity without mentioning photons (or "light") and still keep a straight face.

I have no idea, though, what a non-zero photon rest mass would imply for QED theory and other fundamental theories. That's way outta my league.

Friar Bellows

Depends on what you mean by "interesting". Personally, I think science answers lots of interesting questions. And the most interesting answers generate new questions.

raindropple

E=M(C*C)

This mostly we follow and agree on. Though it could easily have been

E=M(C/2) or so.

We can explain that it is as it is by analaysing and looking at experiments on these topics, though we cant say why it is what it is.

Simply what I hear mostly is, "it is like it is and it works" ,lets just look at that forget why.

[ August 09, 2002: Message edited by: raindropple ]</p>

Philosoft

Friar,

I won't presume to tell you what you learned, but I as I understand it, the graviton was a functional prediction of QM that has never been experimentally confirmed, as opposed to photons and bosons. Basically, the existence of photons and bosons led some to simply presume that there must be a fourth force particle which corresponds to gravity, in the same way photons correspond to electromagnetism and bosons to nuclear force, without any experimental evidence to confirm it. String theory comes in to provide a framework that shows how photons and bosons can be mathematically accounted for by vibrating strings. In addition, string theory provided a vibrational pattern that corresponded to the observed properties of gravity. Hence, the resurgence of enthusiasm for the graviton.

I agree that relativistic gravity is not contingent on the rest mass of the photon. But quantum gravity is, and that's the issue.

Bill,

Indeed, I was speaking in the classical sense. The field of Quantum Electrodynamics has come a long way.

ohwilleke

This statement has real problems with it "could easily have been" implicitly implies either the notion of the existence of a designer for natural laws, or of random chance at work in establishing natural laws.

If there is no designer then this possible implication of the question is not meaningful. And probability is not well defined in a sample with only one example in it. Probability is fundamentally an idea that applies to multiple possible choices of which some number of possible choices become interesting. In the case of the natural laws, we have one example. There are not "alternate" natural laws that apply elsewhere. The mere fact that you could conceive of a different law of nature does not make it a probabilistically meaningful possiblity.

Thus, the notion that a law of nature "could easily have been" something else, is probably based on incorrect assumptions hidden in the phrase. If the truth is the the laws of nature have always been and will always be the same, then nothing else "could easily have been" a law of nature.

For example, a proof that God exists, because our laws of nature allow humans to live, and the laws of nature could easily have been different and not allowed humans to exist, and that the current laws of nature are highly unlikely, is at its root a proof of the existence of God based upon an implicity assumption that God exists.

[ August 09, 2002: Message edited by: ohwilleke ]</p>

Feather

Wait, how does the statement "it could easily have been" imply anything at all regarding design or random chance? That there exists a "law" only means our observations require it. Our observations might have gone differently, or the laws of nature might actually have been different.

If the laws of nature are by design, how are we to know? Likewise with random chance? By what means could we test either hypothesis?

In essence, your statement implies we know external to the natural laws that the laws are correct. Which, given the extensive revision of any number of laws, is certainly not the case.

never been there

Be patient, this does come to a relevant point.

Whimsical physicists did some experiments and found that toast falling off a counter really does fall butter side down. So they sharpened their pencils and put fresh batteries in their calculators and got to work.

Toast usually falls off a counter by being pushed off the edge. The force of gravity gets to work on the leading edge first, so the toast starts to rotate as it falls. Falling from a counter in the usual range of heights, the toast manages about a half-revolution before hitting the floor. The 180 degree margin of error just covers the variation in counter heights.

Now the rotation and falling of the toast are governed by gravity, but why are counters the same height? Because people are around the same height, mostly. And why are we mostly around the same height? Because being taller helps you look further away for food or predators, but increases the risk of skull fracture if you fall. The strength of your bones is a function of how strong the electrical forces among protons and electrons are in the molecules making up your bones. The force of impact is determined by gravity.

It doesn't matter how strong gravity happens to be on earth. Bipedal organisms on a larger planet would be shorter, counters likewise, and toast would fall and rotate faster, and still land butter-side down. Conversely for a smaller planet.

If you go through the math, all the masses and planet sizes and everything cancel out. The only term left which determines that bread MUST fall butter side down is the ratio of G to epsilon (G's electrical counterpart which describes how strong electrical forces are), a fundamental constant of our universe.

In other words, toast falls butter side down because that's the way the universe is.

Friar Bellows

Oh please do! I usually forget what I learn anyway, and have to constantly refresh my brain by relearning. And I have an exceedingly tiny ego, so I don't know why people get irritated by other people trying to teach them something. So thanks for your responses and patience in answering my questions. They're much appreciated.