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Dave W.
Info Junkie
USA
26022 Posts |
 Posted - 09/20/2008 : 10:08:21 [Permalink]
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Originally posted by bngbuck
Dave? Your elucidation of the gamma equation was precise, mathematically accurate, and highly illuminating. What is your understanding of the mechanics of mass increase? |
That'll have something to do with the Higgs field (if it exists). I haven't looked into the mechanism, actually.
By the way, Simon, at 60 miles per hour, all the particles in your body are four ten-trillionths of one percent more massive than at rest. That's like adding two tablespoons of water to Lake Superior. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Cuneiformist
The Imperfectionist
USA
4955 Posts |
Posted - 09/20/2008 : 10:43:19 [Permalink]
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Originally posted by Dave W.
Originally posted by bngbuck
Dave? Your elucidation of the gamma equation was precise, mathematically accurate, and highly illuminating. What is your understanding of the mechanics of mass increase? |
That'll have something to do with the Higgs field (if it exists). I haven't looked into the mechanism, actually. |
This is what I was sort of originally expecting when I talked about not understanding the answer.
In short, as you approach the speed of light you don't gain protons or gluons or something. You just get more mass. And we don't know much about why things have mass.
And now that CERN looks to shut down for a few months, it looks like we're still not going to know much more about mass. |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 09/20/2008 : 11:38:38 [Permalink]
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A couple of months isn't that big a deal with the LHC. Its too bad they are having problems with stuff like circuit breakers and coolant leaks.. heh. They weren't projecting any real definitive answers till sometime next year anyway, so a couple months delay doesn't seem like a big deal for the world's largest and most complex machine.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 09/20/2008 : 11:44:15 [Permalink]
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Ok, here's one for you Dave_W...
If you were to fire two objects (object A and B) in opposite directions at .6c, would a detector on object A observe object B moving faster than light?
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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Cuneiformist
The Imperfectionist
USA
4955 Posts |
Posted - 09/20/2008 : 11:47:37 [Permalink]
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Originally posted by Dude
A couple of months isn't that big a deal with the LHC. Its too bad they are having problems with stuff like circuit breakers and coolant leaks.. heh. They weren't projecting any real definitive answers till sometime next year anyway, so a couple months delay doesn't seem like a big deal for the world's largest and most complex machine. |
Except the article says| The shutdown casts into doubt the hopes of CERN physicists to achieve high-energy collisions of protons in the machine before the end of the year. |
So it sounds like some were sort of hoping that a big-time discovery might have been made before 2009. And maybe it still will! SciAm has news with links to more.
I'm not worried and agree that a machine this complex and huge is almost certain to have its share of glitches. And even if they found the Higgs Boson tomorrow, I still don't think I'd understand it. |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 09/21/2008 : 09:39:55 [Permalink]
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Thanks everyone, BNG expanded on what I was thinking. The kinetic energy becomes mass, that I get, it's the nature of the mass I'm looking for. I guess I'd better get my ass back to school.
Heres another,
How can a massless particle have kinetic energy? |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 09/21/2008 : 11:25:06 [Permalink]
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Originally posted by BigPapaSmurf
How can a massless particle have kinetic energy? |
"Massless" particles have a zero rest mass. When they're in motion (and photons always are), their mass is directly related to the energy they carry (E=mc2). |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 09/21/2008 : 17:34:43 [Permalink]
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Originally posted by Dude
Ok, here's one for you Dave_W...
If you were to fire two objects (object A and B) in opposite directions at .6c, would a detector on object A observe object B moving faster than light? |
Here's a calculator for such problems. The answer is 0.8824c.
The reason it's not 1.2c (which is what an outside observer would see) is that as well as a mass increase, there is also time dilation (also by a factor of gamma). Since velocity is distance over time, the calculation has to account for the slowing of time on object A.
If it could even detect object B. All of B's radiation would be massively blue-shifted.
By the way, I misremembered the equation for gamma. It is this:γ = 1/√(1-v2/c2) Lucky for me, if you work the equation with all velocities relative to c (being 1), then it simplifies to the same equation I put up second. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 09/21/2008 : 20:33:51 [Permalink]
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Originally posted by Dave W.
Originally posted by BigPapaSmurf
How can a massless particle have kinetic energy? |
"Massless" particles have a zero rest mass. When they're in motion (and photons always are), their mass is directly related to the energy they carry (E=mc2).
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Then if photons are moving at the speed of light, how come they aren't infinitely massive?
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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Cuneiformist
The Imperfectionist
USA
4955 Posts |
Posted - 09/21/2008 : 21:07:08 [Permalink]
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Originally posted by H. Humbert
Originally posted by Dave W.
Originally posted by BigPapaSmurf
How can a massless particle have kinetic energy? |
"Massless" particles have a zero rest mass. When they're in motion (and photons always are), their mass is directly related to the energy they carry (E=mc2).
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Then if photons are moving at the speed of light, how come they aren't infinitely massive? |
Quit asking hard questions, kneel down and pray for forgiveness. |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 09/21/2008 : 21:36:10 [Permalink]
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Originally posted by H. Humbert
Then if photons are moving at the speed of light, how come they aren't infinitely massive? |
Because gamma is a multiplier against the rest mass, and photons have no rest mass. The only mass they have comes from however much energy they have. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Simon
SFN Regular
USA
1992 Posts |
Posted - 09/21/2008 : 22:28:02 [Permalink]
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| Maybe I missed it; but does gamma plays a role in the E=MC2 equation? |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 09/21/2008 : 23:12:13 [Permalink]
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Originally posted by Simon
Maybe I missed it; but does gamma plays a role in the E=MC2 equation? |
You didn't miss it, it hasn't been brought up. Einstein's derivation of E=mc2 seems to have begun with the notion that an object has a kinetic energy equal to γmc2-mc2, where m is the object's rest mass. After a few more steps, the famous equation came out.
Gamma itself is more properly known as the Lorentz factor. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 09/22/2008 : 02:07:21 [Permalink]
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Hummer.....
| Then if photons are moving at the speed of light, how come they aren't infinitely massive? |
Good question, Hummer!
I really hate to disagree with the estimable Dave, but based on what I have read in the last week (a lot), I don't believe that in current particle physics parlance, photons are thought to have mass under any conditions! From wiki:| Generalizing this definition to general relativity, however, is problematic; in fact, it turns out to be impossible to find a general definition for a system's total mass (or energy). The main reason for this is that "gravitational field energy" is not a part of the energy-momentum tensor; instead, what might be identified as the contribution of the gravitational field to a total energy is part of the Einstein tensor on the other side of Einstein's equation |
I understand that a photon is considered to be a quantuum - both a particle and a wave-form, depending on the frame of reference in which it is being observed.
But whereas a proton, for example, which has mass at rest would acquire infinite mass at the speed of light (an impossibility); photons exist at the speed of light. Protons acquire mass as they are accelerated, {or else more protons are created from energy during acceleration and this is how the accelerated object gains mass - however I feel that this cannot be the actual scenario, because the object that the protons are particles of would of necessity increase in size - physical dimensions - and I do not see anyone writing that this is hypothesized to take place}
In any event, photons are by definition massless, so they do not acquire mass when accelerated, in fact they cannot be accelerated, only decelerated.
First, photons are defined as massless particles, and they are always traveling at the speed of light, because their impaction upon our senses or instruments is what we perceive as light!
Second, while photons do not have mass, they do have energy and momentum.
Third, the practical problem associated with a particle acquiring "infinite mass" (an impossibility) would be that anything with infinite mass would exert an infinite gravitational pull and absorb everything in the Universe. Photons are, by definition, massless and cannot be thought of in this theoretical framework. They do not acquire mass at speeds of 299,792,458 meters per second or at any speed.
However, it is also true that the idea that "mass" causes gravity is essentially a carryover from Newtonian theory. In General Relativity, it's better to think of energy (and not mass) as causing gravity.
To be really precise, it is the stress-energy tensor that can be thought of as the "source" of gravity in General Relativity.
Energy, momentum, and pressure can all contribute terms to the stress-energy tensor, so they can all contribute to gravity.
Because photons have energy, the problem is resolved. Energy is one of the things that causes gravity, and photons have it. Gravity isn't really a force, but a curvature of space-time. From wikiIn general relativity, the effects of gravitation are ascribed to spacetime curvature instead of a force. The starting point for general relativity is the equivalence principle, which equates free fall with inertial motion. The issue that this creates is that free-falling objects can accelerate with respect to each other. In Newtonian physics, no such acceleration can occur unless at least one of the objects is being operated on by a force (and therefore is not moving inertially).
To deal with this difficulty, Einstein proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths in curved spacetime. (This type of path is called a geodesic.) More specifically, Einstein discovered the field equations of general relativity, which relate the presence of matter and the curvature of spacetime and are named after him. The Einstein field equations are a set of 10 simultaneous, non-linear, differential equations. The solutions of the field equations are the components of the metric tensor of spacetime. A metric tensor describes a geometry of spacetime. The geodesic paths for a spacetime are calculated from the metric tensor. |
It does get rather complex, the more one pursues it!
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Simon
SFN Regular
USA
1992 Posts |
Posted - 09/22/2008 : 09:05:55 [Permalink]
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Ok; I guess I mostly gathered a highly simplified understanding of the phenomenon.
Science is soooooo cool! |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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The speed of light and mass
