Light has some mass, albeit quite small, right (if not, what keeps it from accelerating infinitely?)? If that's so, why does it have a maximum speed (the speed of light) instead of consistently accelerating? And how is it always immediately accelerated to that speed?

I've probably wandered into an area I won't understand with this, heh.

[ 11-20-2002: Message edited by: »Waisztarroz« ]

That is, it can't be pushed by the wind like leaves, meaning it retains a constant speed, whereas something like sand or a dust particle needs an outside force to move it, and is totally dependant on the outside force.

I'm no physics master, so this is basically just a theory.

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A sleep deprived Super Kagrama stammered:
I *think* it's because that light can't be altered by any outside forces.

That is, it can't be pushed by the wind like leaves, meaning it retains a constant speed, whereas something like sand or a dust particle needs an outside force to move it, and is totally dependant on the outside force.

I'm no physics master, so this is basically just a theory.

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Light CAN be slowed down, but not by much. Also you do realise light can be refracted, split into its different parts (omgz the color spectrum) AND it can even be bent (black holes).

Light isnt completley untouchable, but since the light particles are so INCONCEIVABLY SMALL and deathly fast, it isnt an easy task to do what we want with it, or for it to be disturbed by such a weak force like the wind.

Your statement holds truth, but you just missed some things
(not saying im a genius or anything, I could be wrong about some of this too)

To Waisz:

The answer to your question is rather lengthy. You need intense knowledge of the theory of relativity, which I do not have, to know why it does what it does.

Its been answered before, obviously, you're just gunna have to look it up =/

If the mass is almost 0, it requires almost 0 force to accelerate it in any way.

[ 11-20-2002: Message edited by: »Waisztarroz« ]

That, and matter gets larger as it approaches the speed of light--including, I assume, light itself. After a certain point, it probably can't get much bigger, at which point it kind of finds the happy medium which allows it consistancy. I think.

I'm only in tenth grade.

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Ja'Deth Issar Ka'bael stumbled drunkenly to the keyboard and typed:
Actually the speed of light can be slowed down. Scientists have been doing it quite a bit recently, now that they know how. I'll see if I can dig up the article on it.

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They've "frozen" a beam of light in place, which means they've been able to stop light, then make it go again.

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Alek Saege painfully thought these words up:
Light can be stopped to a stand still. However, there is only one substance that can do that and it's name eludes me at this time.

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Einstein-Bossen something.

They just won't get into it this early in the curriculum, I guess.

[ 11-20-2002: Message edited by: »Waisztarroz« ]

[ 11-20-2002: Message edited by: »Waisztarroz« ]

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From the book of »Waisztarroz«, chapter 3, verse 16:
Okay, I'm still a newbie to physics, but as I begin to learn physics equations, I've run across a little question.

Light has some mass, albeit quite small, right (if not, what keeps it from accelerating infinitely?)? If that's so, why does it have a maximum speed (the speed of light) instead of consistently accelerating? And how is it always immediately accelerated to that speed?

I've probably wandered into an area I won't understand with this, heh.

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Actually, it's not quite right to say a photon has mass. It has zero rest mass, there's not really a "particle" there per-say. Instead, it's better to think of light as a wave here, which has energy, which is equivalent to mass (E=mc^2, baby ). Waves of any kind move with definite speeds, and light, which has no preferred reference frame, moves at that speed in all frames. So it's not really a particle, created and instantly accerated. Its, at least for this though pattern, more like a wave in the electro-magnetic field, that moves at the wave speed determined by the properties of the universe.

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I *think* it's because that light can't be altered by any outside forces.
That is, it can't be pushed by the wind like leaves, meaning it retains a constant speed, whereas something like sand or a dust particle needs an outside force to move it, and is totally dependant on the outside force.

I'm no physics master, so this is basically just a theory.

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Again, not quite right. Gravity effects photons just fine (though not in the exact way you'd expect from straight newtonian mechanics. And photons interfere with other photons just fine, so electromagetism also effects it (though it's sort of odd to talk about electromagetism altering electromagetism). Between those two, every macroscopic force out there effects photons.

I don't know about the other two forces, but I imagine it doesn't come up often, considering the scale of the nucleous.

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Actually the speed of light can be slowed down. Scientists have been doing it quite a bit recently, now that they know how. I'll see if I can dig up the article on it.

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Actually, that's not quite right either. In those experiments, they're slowing down rays of light, not individual photons. Yes, light moves (slightly) slower in water and extremely slowly in those experiments, but that's not because the photons are slowing down. Rather, the photons are being constantly absorbed and reemitted, slowing down the net movement, but each photon is still moving at the speed of light in between absorptions and re-emissions.

It's an interesting effect, but not quite that interesting.

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Now, if light went any faster than it did wouldn't it completely fuck with its placement in "time"?
That, and matter gets larger as it approaches the speed of light--including, I assume, light itself. After a certain point, it probably can't get much bigger, at which point it kind of finds the happy medium which allows it consistancy. I think.

I'm only in tenth grade.

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Well, it would be okay if the speed of light was faster, as that would just move the speed limit up, you wouldn't see much in the way of wierd effects. In fact, newtonian mechanics is exactly what would occur if the speed of light were infinite.

As for getting larger, you actually have that backwards. In general, things shrink in the direction of motion, so a meter stick moving at close to light speed would be much shorter (though it would still have the same hight and width)

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Light can be stopped to a stand still. However, there is only one substance that can do that and it's name eludes me at this time.

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Again, that's absorbtion and emission. Its amazing that an atom can hold the photon's information indefinitely, but the photon itself isn't stopping.

Damn waves.

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»Waisztarroz« spewed forth this undeniable truth:
F=ma doesn't really provide much of a range or a domain. The way it's given, it merely seems to work for all forces, masses, and accelerations, but I know there's a domain and range on it.

They just won't get into it this early in the curriculum, I guess.

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Have you done anything in kinematics yet?

WHEEEE equations: Vav = s/t; a = v/t; s = (1/2)at^2 + Vit; Vav = Vf - Vi/2; t = SQRT(2s/a) when Vi = 0;

And before I forget, isnt c an acceleration? Or am I delerious?

Edit: Also, we just talked about the history of c last class in physics - we just got to the aether wind experiment when class ended

[ 11-20-2002: Message edited by: Tegadil ]

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So quoth Ryuujin:
Einstein-Bossen something.

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Bose-Einstein condensate

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Tegadil stopped staring at Deedlit long enough to write:
Have you done anything in kinematics yet?

WHEEEE equations: Vav = s/t; a = v/t; s = (1/2)at^2 + Vit; Vav = Vf - Vi/2; t = SQRT(2s/a) when Vi = 0;

And before I forget, isnt c an acceleration? Or am I delerious?

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Yeah, I've covered a chapter in kinematics. I've also done mechanics (F=ma). The most recent section was cicular motion and gravity/Kepler's laws.

We watched a video on black holes today that got me thinking, "Hey, if light can be drawn into a black hole, it must have some mass so that (G*m1*m2)/r^2 does not equal zero."

I feel cheated.

I have another question now. What if you cheat and use the same object for mass 1 and mass 2 in the equation of force of gravity? The distance from one object to itself is 0, so shouldn't every object exert infinite force on itself?

[ 11-20-2002: Message edited by: »Waisztarroz« ]

Edit: In response to your last question waisz, no. The object has it's own mass pulling itself back out. The distance can never be zero (except in a black hole maybe) because of the whole thing of mass not being able to acupy the same spot.

[ 11-20-2002: Message edited by: Naimah ]

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»Waisztarroz« had this to say about Pirotess:
Yeah, I've covered a chapter in kinematics. I've also done mechanics (F=ma). The most recent section was cicular motion and gravity/Kepler's laws.

We watched a video on black holes today that got me thinking, "Hey, if light can be drawn into a black hole, it must have some mass so that (G*m1*m2)/r^2 does not equal zero."

I feel cheated.

I have another question now. What if you cheat and use the same object for mass 1 and mass 2 in the equation of force of gravity? The distance from one object to itself is 0, so shouldn't every object exert infinite force on itself?

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We're about the same spot. It's Go, by the way. And its the center of mass, not the distance to surface. But by that, yes. HOWEVER, Straubins (best physics teacher. EVAR.) went into detail about that, and how calculus was used to show that if a man were to go to ze center of the earth (presuming one could make it that far) he would be weightless, not infinitly heavy.

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Tegadil had this to say about Pirotess:
We're about the same spot. It's Go, by the way. And its the center of mass, not the distance to surface. But by that, yes. HOWEVER, Straubins (best physics teacher. EVAR.) went into detail about that, and how calculus was used to show that if a man were to go to ze center of the earth (presuming one could make it that far) he would be weightless, not infinitly heavy.

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I meant center. I'm saying the distance from me to me is 0, so I exert (G*m*m)/0^2 or Gm^2/0 N force on myself

What's Go? If you're referring to a variable, realize that variables are named differently from place to place, typically.

And anything divided by 0 is the set off all numbers.

[ 11-20-2002: Message edited by: »Waisztarroz« ]

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And I was all like 'Oh yeah?' and »Waisztarroz« was all like:
What's Go? If you're referring to a variable, realize that variables are named differently from place to place, typically.

And anything divided by 0 is the set off all numbers.

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G sub o. The universal constant for gravity. And I would post the conversation, but its really long, and I don't remember it all. Something about 'chunks' of earth pulling in opposite directions, and balancing out. And as you go deeper into the earth, it shows that it would be like being on a planet with a smaller radius and mass.

I'll try to get him to reiterate tommorow so I can tell you.

Edit: Go = 6.67 * 10^-11
And its a real pain trying to use variables with subs in written typed text.

[ 11-20-2002: Message edited by: Tegadil ]

FG = G((m1*m2)/r^2)

[ 11-20-2002: Message edited by: »Waisztarroz« ]

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»Waisztarroz« enlisted the help of an infinite number of monkeys to write:
That's G, not Go.

FG = G((m1*m2)/r^2)

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You are wrong sir!

Tegadil waves his hands about.

Oooogily boogily!

Edit: Fg (Notice the non capitalization!) = Go*ME (Earth in this case)/ RE^2 so nyah!

[ 11-20-2002: Message edited by: Tegadil ]

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Tegadil had this to say about dark elf butts:
You are wrong sir!

Tegadil waves his hands about.

Oooogily boogily!

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What's Go? If you're referring to a variable, realize that variables are named differently from place to place, typically.

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2. Wind is a force thus it will push on light but the force needed to change it's direction can be considered almost infinite.

3. Gravity affects light thus bringing it as a particle-wave. It's like moving E-fields and Magnetics, the two cannot be seperated. period.

4. E=mc^2 is the simplest form of the equation, it spans over 30 different variables and only tells the maximum possible fissionable energy.

5. Light itself is the instaneous release of energy (this is from the wave based argument) from electrons jumping to higher orbits or lower orbits.

6. Light will decay in energy from impact and rebound. Thus the final EM waves will be about .infinite01 Hz. Yes, SOUND IS A FORM OF LIGHT ENERGY.

edit: any thing you want to comment, please reffer to Tipler Physics and my Physics teacher and many other sources.

[ 11-20-2002: Message edited by: Razor ]

First of all, yes, photons are massless; however that doesn't mean it doesn't have energy and momentum. Momentum is roughly "the ability to push something out of the way", and was understood by Newton and his ilk to be mass times speed. That is to say, a light but fast bullet will do a lot of damage, but so will a slower but heavier baseball. A heavy and fast object (morter shell) will do a whole whopping amount of damage to the target. You can also talk about the kinetic energy in a moving object which is ½*mass*speed²

When a photon strikes an object with a mass, it loses some momentum (and equivalently, energy) and transfers that energy to the struck object. The photon then bounces off at a random angle but it is travelling at the same speed as it was before. The object that the photon hit will be accelerated by the photon and move off in a new speed/direction.

The photon does change though--it changes color (aka frequency), slightly. Incidently, it was the relationship between energy and frequency that won Einstein the Nobel Prize--not his mass-energy equation (that won him years of guilt for ushering in the atomic age). Anyway, here we have one of the Annoying Facts of Modern Science, where a photon strikes an object like a particle but its energy is based on frequency, like a wave. Go figure.

While we're at it, there is a pretty reasonable answer to the old "lumeniferous aether" question; or, "if light is a wave, what exactly is waving?" The thing that "waves" back and forth to make light doesn't really move at all--it's an electric (and magnetic) field changing. It's a bit like running AC current through an electromagnet and holding a piece of iron near it. The field goes up and down in strength and will pull on the iron in different amounts. If you increase the frequency of the current enough, you'll be able to detect another current in the iron as electrons are pulled back and forth. But how were they pulled? Photons, whose frequency matches the frequency of your current.

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Waisztarroz:Oh, sure, when it's not working how you like it, just claim it works under a different set of rules completely.
Damn waves.

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[ 11-20-2002: Message edited by: adenine! ]

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So quoth »Waisztarroz«:
Oh, sure, when it's not working how you like it, just claim it works under a different set of rules completely.

Damn waves.

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Light exists simultaneously as both particles and waves.

It can travel through a vacuum, which implies that its made of particles, since a wave needs a medium to travel through, and there's no such medium in a vacuum.

However, Feynman and Young's Double Slit experiments show that light exhibits wave-like behavior by showing a wave interference pattern in projection.

Here's where it gets interesting. Electrons, like light, have wave/particle duality, and can be run through the Double Slit experiment to the same results. However, any attempt to monitor the behavior of the electrons to get a better idea on what they're doing invokes Heisenburg's Uncertainty Principle, and forces the electrons to behave as particles and immediately their projection loses all the telltale properties of a wave.

It's very interesting stuff, check out this if you're curious about some of the quantum physics involved.

All you need is a microwave oven and a bag of mini marshmellows.

1) Get a microwave without a turntable.
2) Get a microwavable tray as big as possible that will still fit inside the microwave
3) Cover the surface of the tray with miniature marshmellows
4) Run the microwave just long enough for some of the marshmellos to brown. They'll brown in concentric circles.
5) Measure the distance between the dark marshmellow bands and convert to meters.
6) Multiply this distance by 2 (or was it 4?) and then by the microwave frequency, which should be listed on the back of the microwave.
7) The result will be c, the speed of light.

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Drysart was naked while typing this:
It can travel through a vacuum, which implies that its made of particles, since a wave needs a medium to travel through, and there's no such medium in a vacuum.

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My physics professor mentioned in passing that it's been recently theorized that virutal positron-electron pairs formed in the quantum foam can act as a medium for a light wave to propogate through in the vacuum. But without a doctorate in astrophysics, I couldn't begin to explain how that would work. For now, the wave-particle duality will work for me.

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Drysart had this to say about Punky Brewster:
Oh, and something else interesting, you can use waves in the electromagnetic spectrum to show the speed of light as a constant.

All you need is a microwave oven and a bag of mini marshmellows.

1) Get a microwave without a turntable.
2) Get a microwavable tray as big as possible that will still fit inside the microwave
3) Cover the surface of the tray with miniature marshmellows
4) Run the microwave just long enough for some of the marshmellos to brown. They'll brown in concentric circles.
5) Measure the distance between the dark marshmellow bands and convert to meters.
6) Multiply this distance by 2 (or was it 4?) and then by the microwave frequency, which should be listed on the back of the microwave.
7) The result will be c, the speed of light.

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I am trying that this very weekend!

But, yeah, this thread went over my head. There was plenty of clearance between my head and the thread, heh.

Maybe I'll understand...someday.

[ 11-20-2002: Message edited by: »Waisztarroz« ]

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Verily, Karnaj doth proclaim:
My physics professor mentioned in passing that it's been recently theorized that virutal positron-electron pairs formed in the quantum foam can act as a medium for a light wave to propogate through in the vacuum. But without a doctorate in astrophysics, I couldn't begin to explain how that would work. For now, the wave-particle duality will work for me.

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positron + Electron = boom dependant on eachs PE.

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Razor obviously shouldn't have said:

positron + Electron = boom dependant on eachs PE.

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Normally, yes, but these are virtual particles, so they're around for such a brief time that can't annihilate each other.

Light can be slowed, and has been *stopped* already. This is something they're hoping will lead to new 3 dimensional storage techniques.

Light travles at 186000 km/s in a VACCUME. In non-vaccume it's a bit slower, but how much slower depends on what's in the space already. Technically a sheet of paper stops light since it can't pass through the area occupied by the paper. Black holes also have a property that 'stops' light. It actually consumes light as it does any other matter.

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Random Insanity Generator had this to say about (_|_):

Light travles at 186000 Mi/s in a VACCUM.

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Fixxed it up for you, you had units wrong.