[For a slight change of pace, a Hindu fundie...]
How can an object have no mass. If it has no mass, how can it exist? E=mc^2 doesn't apply to an object without mass or momentum. momentum = mass*velocity
So how can a photon have momentum? I think it's all crap to explain crap. Just because it works on planet earth.
Yeah if everyone kept their mouth shut, we'd still be in roman numerals using abacuses. Great advice Arunma.
Every body of mass has gravity ullu.... So why doesn't everything merge into one object? Why isn't the universe collapsing onto itself? Have you heard of strepulsion force? It comes from the Vedas and is now widely accepted scientific fact.
Even I have gravity, but not to the scale of this Earth. My question is, why doesn't the Earth collapse into the Sun? The sun into a bigger star? The star into our galaxy, and our galaxy into a black hole. Why is keeping objects from hitting each other? The largest mass should be absorbing everything.... Why isn't it?
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As a first year science student, I can answer most of those questions.
Every body does exert a gravitational force on every body, which is proportional to their masses, and inversely proportional to the square of the separation (in Newtonian mechanics; general relativity is slightly more refined). Thus, in space, the gravitational force between galaxies, being super far away from each other, is very small. As for the Earth collapsing into the sun question, I can't demonstrate it fully to you without using maths, but gravity acts only in the direction of the line between the two bodies. Thus, if a body has a velocity at 90 degrees to this line, the force pulls the bodies together, resulting in them spinning, relative to each other. If this velocity is fast enough, the force will simply make it shoot round and never be strong enough to pull it back. Since the force diminishes with the square of separation, the velocity after it comes around will reach a limit, as the force, and hence acceleration, approach zero. If it is slow enough, the bodies spin round, but eventually hit one another (imagine water going down the sink). If it is just right, the bodies orbit one another (they could actually be collapsing or diverging, but very slowly). Since the sun is so heavy compared to the Earth, the Earth does most of the moving. As for the photon one, I don't know, it just does. Think of E=mc^2 as E=pc, where p is momentum.
A photon, while having no mass, most definitely has an effective momentum. It's weird, but that's what you get in quantum mechanics.
Why doesn't everything collapse?
Partially because gravity is millions of times weaker then the electromagnetic/atomic forces, or people would just fall to the center of the earth, because the atoms wouldn't repel each other.
What's really funny is this: srev has had his ignorant ass handed to him by several posters on that forum (including arunma!), and he is just too damned dense to get it. He keeps going on about "how can something have momentum if it doesn't have mass", all the time claiming to have taken "several classes" in physics.
Lying for Brahma?
Photons have no rest mass. Photons have energy, and therefore, mass: m=hf/c2 , where h is Planck's constant and f is the frequency of the photon.
"Wh[at] is keeping objects from hitting each other? The largest mass should be absorbing everything.... Why isn't it?"
The earth is falling toward the sun. Any good high school science book should explain this, complete with handy pictures. We're not sure everything isn't going to fall back together eventually. That's still an open question, last I heard. Also, we've never found a repulsive force, but that's not to say one doesn't exist. If you find it, you'll probably win a Nobel Prize and go down in history alongside Einstein.
I'm not an expert by any means, but from what I can find on the internet that stellar repulsion force sounds a bit hoaxy. Until I read this I'd never heard it, and it definitely doesn't seem to be widely accepted since there's hardly any info on it.
You know, aside from this, I have to give the Hindus a lot of credit, at least in my experience. I work with a lot of Indians as an IT professional (honestly, there are more H1B programmers at my company than Americans, and that's not counting those we've hired offshore), and to this day I have yet to hear a single word about their religion from any of them, except once when directly asked by someone (and yes, I do realize that not all Indians are Hindu). Would only the Fundies be so considerate.
@EspadaDelDios
There are fundies and extremists from every religion. Strangely enough, and I freely admit that I will probably never comprehend this one, there exists a militant group of Buddhist extremists.
Oh, it could be a number of things. I would go with a combination of gravity weakening over distance, with some momentum for orbit, or, such as in meteoroids, a velocity to escape gravity.
Naw. That's probably just a wild theory that pretty much every single scientist on the planet agrees upon...
At least he knows a little bit about physics...
Though he forgot that photons actually have mass and momentum. m=h*f/c^2, with h being the Planck constant and f the frequency of the photon. So yeah, the mass is pretty damn small.
It only has no mass when it's not moving, but that is not possible.
And that the earth does not fall into the sun because of a funny thing called centripetal force.
For E = Energy, m = mass, c = speed of light, and p = momentum:
E = sqrt((mc^2)^2 + (pc)^2)
If pc << mc^2, then you can approximate and get E = mc^2. Photons have no mass (or at least it is less than 10^-18 eV), but they do have momentum.
Confused?
So were we! You can find all of this, and more, on Fundies Say the Darndest Things!
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