quote:

---

Originally posted by kuru:
the truth is, nobody really understands why light behaves the way it does.

---

You could say that again. When it gets down to the nitty gritty, the best answer anyone can come up with is "because".

quote:

---

Originally posted by kuru:
all other things aside, in this instance we would have to say that light has mass, else gravity could not affect it. however, light is energy, it has no mass. so photons, those little quantized packets of energy, obviously behave like matter at some point. but why don't they weigh anything?

---

You are forgeting a fairly famous equation proposed by our friend Einstein, E=mc^2. Although photons have a zero rest mass, they have a mass equivelent due to their energy. That aside, the presence of matter warps the fabric of space-time (mmm cliche). Light always travels in a straight line - as defined by space. If space itself is bent, then the path that the photon follows will appear to bend as well. This was shown in about 1918 when there was a total eclipse of the sun and the position of some stars seem to have been moved. The light from the star passes by the sun, and they are bent due to the warpage of space. This was the first proof of Einstein's Theory of Relativity.

quote:

---

Originally posted by kuru:
everything that absorbs photons (like a black cloth in the sun) would 'weigh more' as it absorbs more photons. except it doesn't.

---

The energy absorbed in the visible spectrum is re-emitted as heat in the infrared. That is why black things get hot.

quote:

---

Originally posted by kuru:
for example, black holes. we know of them as singularities. infinitely collapsing balls of matter that continue to fall in on themselves forever, becoming more and more dense. ok, that's great. except that singularity is a pretty weird concept.

---

Physicists don't like singularities. We hate all things to do with infinity. Singularities are a wierd concept because the laws of physics, as we know them, cannot be applied to them. Although, that doesn't stop people from trying...

One such thing that has been proven (as much as anything can be proven in science) is the existance of Hawking radiation. This is where a black hole emits radiation. Conventional analysis of black hole physics says that this is impossible. Stephen Hawking showed that it is possible. A vacuum is not totally empty. It consists of lots of particles spontaneously appearing, as pairs, ie positron/electron, and then disappearing before the rest of the universe notices. If one of these pairs happens to appear right at the event horizon of a black hole, one of the particles will be sucked in, and the other will be left on its own, free to interact with the rest of the universe. So for all intents and purposes, the black hole has emitted some radiation.

quote:

---

Originally posted by kuru:
so where are the white holes? where are the things that expand constantly, becoming less and less dense? theory: universes.

---

People are looking for white holes, but I don't know much about any of the results. As for 'expanding constantly' that depends on the Hubble constant. There is some evidence that the expansion of the universe is actually speeding up. This seems to confirm one of Einstien's hunches that gravity can push as well as pull. But this work is still in progress...

quote:

---

Originally posted by kuru:
another one can be done with simple quadratic equations. we all did them in algebra, and we all solved ones in which the "answer" was a negative square and we were told to just 'throw that one out.' imaginary numbers are nice and all, but they don't exist. right. except that mathematics, done correctly, doesn't produce wrong answers. so negative squares exist, and they do complete that equation, somewhere. just not in our known universe. we don't know of a place where there is a number that when squared = -1. really though, higher math shows us that imaginary numbers are just another dimension of a number. that all numbers have a real and imaginary component, and that most of the numbers we deal with have '0' as their imaginary component, so we only see a one dimensional number that sits on a line.

nice, except that somewhere else, there are those numbers that don't fit on the line. the ones that must be described as a point in a plane. a two dimensional number. 2+3i, and such.

these numbers don't fit into a 3 dimensional universe, but they do fit in somewhere. another universe? maybe.

---

Using your arguement, negative numbers cannot exist. Can I hold -3 apples in my hand? No, I can't. Back in Pythagoros' time, he executed a student for suggesting that irrational numbers exist, that is numbers that cannot be expressed as a ratio of two whole numbers.

And yes, we do know of a place were a number square equals -1. It is this universe. i^2=-1.

The base numbers are the integers. These are ...-3, -2, -1, 0, 1, 2, 3... From these numbers we construct the rational numbers, which are ratios of the integers eg 2.5, 104.7, 1/3 etc. We must then construct the irrational numbers, numbers that can't be expressed as a ratio of integers. eg sqrt(2), pi, e etc..
All of these numbers are known as the real numbers. After this, we need to construct the imaginary numbers. With all of these numbers, so far we can solve all equations.

The plane that you refer to is known as the Argand plane. The real axis run from -ve infinity on the left, through zero, to +ve infinity on the right. The imaginary axis runs from -ve infinity*i at the bottom, intersects the real axis at zero, and goes up to +ve infinity*i at the top.

I think that sounds coherent.

Note to solid, I found his name, see below...

edit: grammar, spelling and a couple of additional points
------------------
"All is number" - Pythagoras

This message has been edited by masher on January 15, 2001 at 09:09 PM

as far as the einstein equation, did you also know that the equation you quoted has NOTHING to do with light being matter?

ALL energy is mass*velocity^2. it's just that in the case of DIRECT conversion of matter -> energy, you use the speed of light. einstein also figured out that his equation wasn't entirely correct, something which bothered him immensely, because he hated having to use a 'fudge factor.'

thus, there's no real mass equivalent of a photon, because nobody can actually measure a photon as a photon. we have to wait till it hits something to determine where it is and how big it is, which means we've already altered the speed of it, so it's not really traveling at c anymore. heisenberg's uncertainty principle applies here.

moreover, every scientist knows that a vaccuum is not entirely empty. 'empty space' is not empty at all, and while the 'infinite expansion' of anything cannot be proven because we lack the ability to measure a signifcant enough period of time. also, time doesn't exist. the only thing differentiating time is 'now' and an 'instant from now.' it's the property of things not happening all at once. space and time are really one and the same thing, which like all of quantum physics, nobody really understands it (neils bohr pointed that out.)

the bottom line is that we probably never will understand all of quantum physics because we live inside it. the simplest law of physics is that you can't understand a system you're part of. so obviously understanding the universe is a futile thing, and even fully understanding man is a futile thing.

so why are we here?
heh. human beings don't deal well with this, because it's in our nature to ask 'why?' all the time. but hey, maybe we have to accept the fact that there is no 'why'. at least, not one that will ever be understood by the participants in the system they're tryin to study.

------------------
kuru
'dancing is the vertical expression of horizontal desire.'
-robert frost

"Planke's constant is neither.. haw... haw... haw"
- Stephen Hawking on Simpsons

Space time is not actually four-dimensional, as we assume, it's actually either 10- or 11-dimensional, with the extra 6 or 7 dimensions curled up really small so we can't see them. What we call "particles" are actually tiny 1-dimensional strings or higher-dimensional membranes resonating at different wavelengths, with each distinct resonation producing a different elementary particle. And matter can't shrink to a point, because the possible quantum paths of all those strings wrapped around space keep it from shrinking to a size smaller than the Plank size. But that doesn't keep space from tearing and re-forming in wormholes and the like.

Yes, it supposedly is a "Theory of Everything" but it's also, in my opinion, even less intuitive than quantum mechanics, and so complicated that no one even knows how to do the math involved directly. Yes, it is a very promising theory, but they're going to have to simplify it a lot before it can really be useful.

quote:

---

as far as the einstein equation, did you also know that the equation you quoted has NOTHING to do with light being matter?

ALL energy is mass*velocity^2. it's just that in the case of DIRECT conversion of matter -> energy, you use the speed of light. einstein also figured out that his equation wasn't entirely correct, something which bothered him immensely, because he hated having to use a 'fudge factor.'

---

It has everything to do with it. What is light but energy? And what is energy but an alternative expression of mass? Also Einstein’s ‘fudge factor’ was nothing to do with E=mc^2. It had to do with his equations that govern the expansion of the universe. His equations implied that the universe was expanding. In his time, the entire known universe was just the milky way, and our galaxy is too small to observe any expansion. Therefore he put in his fudge factor to negate the expansion put there by his equations. When the rest of the universe was discovered, and the expansion was shown to be true, he called his use of the fudge his greatest error

quote:

---

thus, there's no real mass equivalent of a photon, because nobody can actually measure a photon as a photon. we have to wait till it hits something to determine where it is and how big it is, which means we've already altered the speed of it, so it's not really traveling at c anymore. heisenberg's uncertainty principle applies here.

---

You can measure the wavelength of a photon to extreme accuracy. This measurement spreads out the position of the photon, so you just don’t know where it is – this is the uncertainty principle. It can be shown that the momentum of a photon is given by p=E/c, where E is the photon energy and c is the speed of light. The energy of the photon is given by E=hf where h is Planck’s constant and f is the photon frequency. If we plug all the numbers into the equations, we get a value for the momentum of a photon. Now, to have momentum, a body must have mass. As the photon has a zero rest mass, the mass is a mass equivalent.

quote:

---

moreover, every scientist knows that a vaccuum is not entirely empty. 'empty space' is not empty at all, and while the 'infinite expansion' of anything cannot be proven because we lack the ability to measure a signifcant enough period of time. also, time doesn't exist. the only thing differentiating time is 'now' and an 'instant from now.' it's the property of things not happening all at once. space and time are really one and the same thing, which like all of quantum physics, nobody really understands it (neils bohr pointed that out.)

---

We can measure a long enough period of time just by measuring galaxies at different distances from our own. The problem lies in the errors associated with the measurements. Time does exist. Its length is relative, according to the Theory of Relativty. It can also only run in one direction, according to one of the laws of thermodynamics (I think it’s the 2nd)

quote:

---

the bottom line is that we probably never will understand all of quantum physics because we live inside it. the simplest law of physics is that you can't understand a system you're part of. so obviously understanding the universe is a futile thing, and even fully understanding man is a futile thing.

---

I would have to agree with you here to a certain extent. The mere act of observation disrupts the system being observed. But that aside, it doesn’t mean that we are incapable of understanding it. It is just the level of understanding that you wish to gain. At the base level, the answer is always going to be ‘because’.

quote:

---

so why are we here?
heh. human beings don't deal well with this, because it's in our nature to ask 'why?' all the time. but hey, maybe we have to accept the fact that there is no 'why'. at least, not one that will ever be understood by the participants in the system they're tryin to study.

---

This is where some people invoke the anthropic principle. We are here because a whole bunch of variables got the right values. Planck’s constant, the gravitational constant etc.. We exist to observe the universe around us. This principle was used by Fred Hoyle to show that a certain type of reaction inside stars involving carbon existed. His reasoning was that if the cycle didn’t exist, neither would we. It was later shown to be true.

------------------
"All is number" - Pythagoras

STFU KURU AND MASHER U ARE MAKING MY BREAIN CAVE IN

how the flying fuck are any of us supposed to understand what the hell you guys are talking about?? goddam i wish i was smart enough to grasp all that. you ppl are freaks

the only thing i have to add to this discussion is on the 'multiverse' thing. i personally prefer Piers Anthony's word for the eternity of alternates - Alternity

------------------
"I didnt know cows had boobs, I just thought they had that big nutsack with all the wieners hanging off it" - Beavis

Metal/Electronic/Ambient etc..
http://www.mp3.com/fatbitch

heh :)

the only way you know how far a galaxy is from our own is by using LIGHT to measure it, in order to prove the assumptions you made about LIGHT.

you also have to assume a time which the galaxy was not that far away, and that you knew where it was then, and how long it took to get where it is.

all of these things are assumptions. and while they do make pretty little equations that all prove each other, they're still circular logic, because you're proving the thing you're looking for using the thing you're proving.

it's like this: you can't use the word you're trying to define in that word.

now you can quote equations all day long, but the bottom line comes down to the fact that you are trying to prove things about photons by using equations that make assumptions about photons.

there is NO experimental data to back /any/ of it up.

einstein fudged a lot of his theories. and remember, relativity is still a THEORY. it's never been proven (or rather, there's never been a concrete lack of disproof shown), and there probably never will be, because EVERYTHING we've discussed here violates the simplest rule of physics.

an observer cannot understand fully a system which he is part of.

------------------
kuru
'dancing is the vertical expression of horizontal desire.'
-robert frost

------------------
Leaving the trees was a bad idea.
TeamWolfguard.com