How does mass increase? Does that not break the rule of conservation of matter? Do you suddenly gain a couple of trillion, trillion, trillion tons (metric or standard? [img]/phpBB/images/smiles/icon_smile.gif[/img] )in a couple of seconds? But theoretically would your nose be travelling faster than light IF you can fall over? Or am i misinterpreting this. Does your gravitation mass increse making it seem like your physical mass increases?

Here is another theory, if you were going faster than the speed of light, would your body not physically be able to fall over because of the speed barrier? Would it be like hitting a invisible wall?

I have another idea of how to make a anti-grav devcice. Find out what in our atoms the gravity is actually affecting and somehow block that interaction by some sort of gravity shielding device. That way we don/t affect the gravity field of anything except around us. But this won't crerate artificial gravity , we would actualy have to think of something else, like maybe buid a ship around the core of a neutron star?

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GIYUL :-)
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

Another convervation law? This place is getting way too conservative. I'm moving to a new universe.

So if gravity is a wave can we send out a "Anti-Grav" wave of the opposite magnitude and amplification and wavelength to cance out the gravity?

At some point in space between two massive bodies isn't this sort of what happens?

Tom

So that means that there is some sort of horse lattitudes in space? Now gravity (wind) so any object there gets stuck. So would not there be a amalgamation of asteroids, comets and other junk in that area?

P.s. There is not a law for the conservation of matter? I thought that went along with conservtion of energy. Opps i guess i better take physics again. [img]/phpBB/images/smiles/icon_smile.gif[/img]

<font size=-1>[ This Message was edited by: g99 on 2002-07-27 01:15 ]</font>

Yep, actually there are such points. In a two-body orbiting system there are 5 points where the two bodies gravities cancel out. These are called the LaGrange Points L1-L3 are unstable, that is, a slight push would be enough to send them moving away from the point, so objects don't collect there, but they can reside temporarily. L4 and L5 are stable points, and objects there tend to stay there. There are many Trojan asteroids in the Lagrange Points of Jupiter, and dust clouds have been detected in the Lagrange points of Earth.

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<font size=-1>[ This Message was edited by: David Hall on 2002-07-27 04:12 ]</font>

We went round-about on the nature of gravitational propagation on a thread in the Against the Mainstream section a couple of months ago.

All reputable physicists that I wrote to and that I know of agree that gravity propagates at the speed of light. However, just as with electrical fields the laws of physics require an adjustment to the vector of attraction which, in smoothly varying systems, makes the vector of attraction point at the instantaneous position of the attractor rather than the position it occupied one lightspeed-propagation transit time in the past.

I think it was Kip Thorne that wrote that physicists have a toolkit of equations that treat gravity as a field in flat spacetime, and this toolkit is very useful in describing the genesis of gravity waves (the quadrupolar time-varying fields described by someone in a previous post). They have another toolkit of equations that treat gravity as a geometrical curvature of spacetime, and this is spectacularly successful in describing things like black holes. Quantum physicists are working on quantum gravity, and perhaps that will include a zero-mass 'graviton' as the particle which mediates the gravitational force. If that works out, then there will be a third toolkit of equations.

But Thorne's point was that it is actually uninteresting to him which of these alternate descriptions is "really" gravity: when the equations from the toolkits are applied to the same problem they give exactly the same predictions. Therefore it's experimentally impossible to distinguish between them, and they can all be regarded as scientifically correct.

That material is in Thorne's book for lay audiences, "Black Holes and Time Warps: Einstein's Outrageous Legacy." It is one of my favorite science books of all time. Your local library probably has a copy... [img]/phpBB/images/smiles/icon_wink.gif[/img]

Don Stahl

Addendum and caveat: I have a great tendency to misremember stuff that I've read some time in the past. I'll see if I can look that passage up and verify what I've written.

<font size=-1>[ This Message was edited by: DStahl on 2002-07-27 05:11 ]</font>

The mass does not increase in the sense of there being "more stuff". What happens is this: at slow speeds, if you apply a force to a mass, you get a certain acceleration, and we call the constant of proportionality between those two quantities "the mass".

F=ma; Force = mass times acceleration

As you get closer to the speed of light, the same amount of force produces less acceleration. If you still want mass to be defined as "the proportion between force and acceleration", then mass has to increase in order to keep the equation valid (if F stays the same and a goes down, then m must go up). However, if you want to think of mass as "the amount of stuff" (relativity theory calls this the "rest mass"), then it is more accurate to say "the same amount of force produces less acceleration". It is a property of space, not of matter. Saying "the mass increases" is just a shorthand way of saying "the same force produces less acceleration", and I think it's misleading, because it gives people the impression that "more stuff" appears out of nowhere. Still, it's in all the textbooks, because they think it's easier for people to get the concept if they frame it in terms of something familiar (F=ma). I disagree.

Don

The following link explains why would expect you to turn into a black hole before you reached light speed;

The Effects of the Special Theory of Relativity


So basically as a result of special relativity as you get closer to the speed of light your mass increases. At light speed you would have infinite mass, so therefore before you reach light speed you will obtain sufficient mass to turn into a black hole !

Phobos

<font size=-1>[ This Message was edited by: Phobos on 2002-07-27 11:06 ]</font>

Hmmm...very interesting. I have never heard f=ma in that way. I have always heard it in the usual terms. Thanks...

I think i am actually getting it. This is a first [img]/phpBB/images/smiles/icon_smile.gif[/img].

So If you constantly gain mass to a infinite amount, how come the light particles do not all become black holes? Why is space not one giant black hole? I can understand that they are not accelerating anymore, but the initial acceleration of the particles would produce a giant black hole in the center of every star, would it not? Or do the particles start out at the speed of light, thus no acceleration, and thus no mass change?



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<font size=-1>[ This Message was edited by: g99 on 2002-07-27 13:54 ]</font>

Phobos and g99, please go back and reread Doctor Don's post. The rest mass does not increase. Only the relativistic mass increases (to keep the equation F=ma in balance). In other words, to the force pushing the object, the mass seems to increase (acceleration per unit force decreases). The mass, as perceived by the rest of the universe, does not change. In other words, an object with a rest mass of one gram moving at 0.999...c may have the relativistic mass of a small planet (with corresponding energy release if it hits something) but gravitationally, it is still only one gram and is not going to turn into a black hole.

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But still, would a particle of light have the relativistic mass of a black hole? or does it start out at the speed of light, so there is not acceleration, and thus no relativistic mass change?

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GIYUL :-)
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

Light always propagates at the speed of light (or less, in media other than a vacuum), when measured by any observer. This is the very essence of relativity.

So it's senseless to talk about what happens as light "accelerates". It doesn't.

What's more, light has zero rest mass, so there's no mass to increase. It does, of course, carry energy, and so can be said to exert a pressure, but it's not quite the same kind of pressure as is exerted by, say, the molecules of gas in a diver's air tank.

That's not how I've always heard it defined. The definition I've heard is when you are faced with a situation where there is a proposition A which may or may not be true. If the conditions are such that the consequences of winning or losing a bet based on the proposition that A is true are much greater than the consequences if A is false, then Pascal said it's best to bet that A is true, since you are risking less if you lose and win more if you win. The classic example of such a wager is where A is "God exists". Pascal said you should believe in God because it's the least risky scenario. If he doesn't, he can't reward or punish you for your choice, but if he does, he can, so better to behave as if he does.

Although this does get trotted out quite a bit by certain missionaries I have encountered, I think it is theologically ludicrous (Despite the ample evidence that hordes of people think about it this way, religion is not about greed for reward and/or fear of punishment.), and mathematically dubious (as it assumes mere belief in God is sufficient to earn the reward in question, and it also fails to put much weight on the idea of having wasted your life behaving as if there were a God if it turns out there isn't).

> The lottery is a perfect example of Pascal's wager.

I disagree. First of all, the known improbability of winning the lottery weights the choice a priori. I think Pascal's wager demands no prior information be known on whether the proposition is true. Also, without the threat of punishment, the loss category in the event of A being true does not provide enough of a risk to balance out the known loss if A is not true. I.e., if A is true and I buy a ticket, I win big. If A is not true and I buy a ticket, I lose a little. If A is true and I don't buy a ticket, I lose nothing, and if A is not true and I don't buy a ticket, I also lose nothing. That clearly pushes the answer to not buying a ticket, escpecially given the improbability factor, which is not how I understand a Pascal's Wager to operate.

But then, I've never heard Pascal's Wager refer to anything but the belief in God question, so perhaps I am generalizing it incorrectly.

Don

Light has no mass and is best thought of as matter completly converted into energy.

Phobos

Wow, lots of deep questions flying around here. Let me see if I can answer a couple of them...

Gack! Oh, no, no, no. This is completely and utterly wrong. The only part that is right is the definitions of the letters. The rest is wrong. Please don't get misled by this. Please see my description for a more accurate explanation of why the "mass increases".

Donnie B. is quite right that a photon does not accelerate. It has no rest mass, so it cannot move at any other speed than the speed of light. [The fact that light moves slower when not in a vacuum has to do with how light interacts with the atoms in the material. Since any material is mostly empty space between the atoms, you can think of the light waves as racing at the speed of light through the vacuum between the atoms, but being slowed down by all the interactions it has along the way through the macroscopic material. (Okay, so that's a gross simplification, but I think it's not wrong within its limitations.)]

However, folks are getting to a more subtle point. While the relativistic mass does not curve space the way the rest mass does, general relativity *includes* energy in Einstein's Equations for the curvature of space. For that matter, *pressure* can cause space to curve, too. So I think it's a valid question to ask whether a particle accelerated near the speed of light, or an energetic photon, would collapse into a black hole. I believe the answer is that it's just not possible to give a single particle that much energy, massless or no. They would use that energy to decay into something else before you could get anywhere near energetic enough. And they're moving so fast you can't constrain enough of them in a small enough space to cause collapse, either. That would be my guess, but I'm not an expert. I'll ask the Relativist down the hall.
Yours,

Don

Put yourself in the driving seat of your 1gm spacecraft with the relativistic mass of a small planet. Your spacecraft will be pushing with the required 1 planet force and will in turn be receiving an equal and opposite reactive force of 1 planet pushing back to aquire the required accelaration.

Keep accelarating and our spacecraft will keep receiving ever greater forces pushing againt it - what will happen when our spacecraft requires more than the weight of an entire galaxy to continue its quest to reach light speed ?

I suspect it would be a black hole before it ever reached the velocity described above.

Phobos

Wiley and DoctorDon – Thanks for the descriptions of a “Pascal’s wager”. I had never heard of it before – now to do some more research.

In the book "Pushing Gravity" I describe the cause of gravity as being a push from overwhelmingly long wavelength cosmic background electromagnetic radiation. The graviton becomes a quantization of the shadow cast by a mass in this radiation field and it travels at the speed of light. As masses aproach c the are slowed as though they increase in mass per the above discussion on the relation between force and acceleration. This provides a "reason" for special relativity. These are not yet the mainstream.

back to one of my original questions...What does gravity actually attach to or push? Is there a physical interaction or is it purely ralativistic?

John Kierein describes "The graviton becomes a quantization of the shadow cast by a mass in this radiation field and it travels at the speed of light." Is this a explanation of how gravity works? If so(or if not) can someone explain this in more stupid person lanugage for me? I did not get a degree in physics, only anthropology with some astronomy and geography, so i am not a physics expert (that is why i started this discussion [img]/phpBB/images/smiles/icon_smile.gif[/img]).

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GIYUL :-)
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

Here's a good link about Pascal's Wager, with arguments pro and con...

http://plato.stanford.edu/entries/pascal-wager/