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Messages - burning

Pages: [1] 2 3 4
1
New Theories / Re: How can the speed of light be faster than time itself?
« on: 31/10/2015 16:36:10 »
Quote from: Thebox on 31/10/2015 10:03:01
9,192,631,770 Hertz (Hz, or cycles per second)=1 second = 0.0288mile per second=46.3491072 meters per second


c=299 792 458 m / s

299 792 458 / 46.3491072=*6468138.7865 faster than time

You can't equate different units of measure the way you did, so the calculations are not sensible.

Conceptually, it doesn't work either. Time is not something that moves. There is no "speed of time," so the speed of light can neither be faster nor slower than it.


2
Physics, Astronomy & Cosmology / Re: would a vacuum baloon float quicker than our lightest gases?
« on: 31/05/2015 20:57:41 »
The vacuum balloon has the problem that the skin would need to be rigid to keep it from being crushed by atmospheric pressure. The buoyant force on a balloon depends on its total mass, so while the empty interior would contribute negligibly to the mass, you would still need to take into account the mass of the skin. It would be difficult to make a skin sufficiently rigid but that was still light enough to float in the air.

The helium in a helium balloon of course is more massive than the same volume of vacuum would be, but the helium exerts pressure on the inside of the balloon to balance the external pressure of the atmosphere. Consequently, a helium balloon requires a much less rigid skin (which tends to mean consequently less massive).

However, if we assume the existence of a sufficiently light and rigid skin, then you are correct that this skin filled with nothing would have a greater buoyant force on it than if the same skin were filled with helium.

3
Physics, Astronomy & Cosmology / Re: matter/anti matter
« on: 27/01/2015 22:29:36 »
Quote from: JohnDuffield on 27/01/2015 21:57:10
Quote from: burning on 27/01/2015 14:02:09
So I read the linked article. The quark-gluon plasma doesn't do what you want it to. First off, it has nothing to do with electrons. Electrons are not composed of quarks.
Nor is a quark-gluon plasma. A quark-gluon plasma isn't a mess of quarks and gluons buzzing around. Hadrons melt in it. They don't split up into quarks and gluons. And if a hadron melts, an electron will melt too. Note that gluons in ordinary hadrons are virtual anyway, see this. Quarks are just partons. Parts.

Followed your first link. Within it was the following sentence which directly contradicts your assertion about what a quark-gluon plasma is.

"Beyond the normal phase of QCD (at extreme temperatures and pressures), quark gluon plasma forms. In such a plasma there are no hadrons; quarks and gluons become free particles." (emphasis added)
Quote
Quote
Indeed, most physicists believe that electrons aren't composed of anything smaller. (Every so often I hear about proposals of benefits of considering the electron a composite particle, but I'm not aware of any that have stuck.) So the electrons aren't going to melt.
Yes they are. If a proton cannot maintain its integrity, nor can an electron. See this about heavy-ion collisions where everything “melts” into a quark-gluon plasma.

Followed your second link. It makes no mention of electrons or positrons, so I don't see how it supports your assertion.

Protons are believed to be composite particles. Electrons are not believed to be composite particles. The dissolution of protons under high energy conditions does not carry any implications about what happens to electrons.

At this point, I'm bowing out. Your main point has basis neither in the physics I learned in graduate school nor in the references you claim support it. I'm at the limits of my ability to recast my explanations in new words that will be any clearer or more helpful than what I've said up to this point.

4
Physics, Astronomy & Cosmology / Re: matter/anti matter
« on: 27/01/2015 14:02:09 »
Quote from: JohnDuffield on 26/01/2015 21:15:47
* see this: http://www.livescience.com/14748-quark-gluon-plasma-particle-soup-rhic.html

So I read the linked article. The quark-gluon plasma doesn't do what you want it to.

First off, it has nothing to do with electrons. Electrons are not composed of quarks. Indeed, most physicists believe that electrons aren't composed of anything smaller. (Every so often I hear about proposals of benefits of considering the electron a composite particle, but I'm not aware of any that have stuck.) So the electrons aren't going to melt. Even if the quark-gluon plasma provided an answer for the lack of anti-protons, it wouldn't provide one for the lack of positrons.

Second, the quark-gluon plasma just pushes the matter/antimatter problem back one step further, rather than getting rid of it. Quarks have anti-particles as well. Indeed, if they didn't, then the particles they made up wouldn't have them either. A proton is made up of two up quarks and a down quark. An anti-proton is made of two anti-ups and an anti-down. So the question in the early universe is "Why are there more quarks than anti-quarks?"

So we're back to a choice between what I described above as options (1) and (2). As others have been pointing out, the bulk of research has centered around option (2), that there was a real imbalance. There does seem to be some progress in that recently, as the material mentioned by Ethos_ and the article linked by jeffreyH show.

5
Physics, Astronomy & Cosmology / Re: matter/anti matter
« on: 26/01/2015 20:44:27 »
No. If they are exactly evenly matched, then it is a tie.

Are you saying

(1) It is a tie, but we just happen to have electrons and protons in this part of the universe but they are all balanced by positrons and antiprotons somewhere else? This raises the problem of why we never see evidence of clumps made of electrons and protons (like what we live in) running into clumps made of positrons and antiprotons.

(2) It is not a tie. There actually were more electrons than positrons and protons than antiprotons. This raises the problem of how this happens when the physical laws governing them seem to be symmetrical.

or

(3) Something else. (If so, please explain, because I sincerely can't think of a third option between "it is a tie" and "it isn't a tie.")

6
Physics, Astronomy & Cosmology / Re: matter/anti matter
« on: 26/01/2015 20:24:26 »
No, the mystery does not go away. The "mystery of the missing antimatter" is shorthand for the individual mysteries of the missing positrons, the missing antiprotons, etc. Relabeling antiprotons as "antimatter" does not make it less mysterious that we've got a lot of protons and a lot of electrons and apparently negligible amounts of positrons and antiprotons.

7
Physics, Astronomy & Cosmology / Re: matter/anti matter
« on: 26/01/2015 19:39:48 »
Quote from: JohnDuffield on 25/01/2015 23:10:02
No. Matter.

I may be missing the point, but you seem to be changing definitions without proposing a change in how particles actually interact, but then concluding there is a grave error in physics for what is essentially a symantic difference.

The broad categories of matter and anti-matter are useful for brevity of expression, but the only thing that really matters (pardon me) is the interaction between a particle and its specific anti-particle. An electron will never annihilate with a proton. Nor will it annihilate with an anti-proton. It will only annihilate with a positron. Similarly a proton will only annihilate with an anti-proton.

Physicists have traditionally called both electrons and protons (and neutrons, although you don't bring them up)matter. This is a simple expediency, since these are the particles that make up the world around us. We've called this stuff "matter" long before anti-matter was conceived of by the human mind. Anti-matter is the catch-all term for the antiparticles of the ones we call matter.

Unless you are proposing new mechanisms for how the particles actually interact, however, swapping the matter and anti-matter labels on protons and anti-protons is simply that: swapping labels. It has the disadvantage of being linguistically confusing, but it does not in itself have any physical content.

8
Physics, Astronomy & Cosmology / Re: List of useful math/physics resources
« on: 22/01/2015 15:55:47 »
Neither of you make a good impression in this thread.

Returning to the original topic, here are a couple of places where you can legitimately view physics journal articles for free.

http://arxiv.org/

http://iopscience.iop.org/

9
Physics, Astronomy & Cosmology / Re: Why do some lottery combinations seem impossible?
« on: 11/11/2014 19:28:30 »
Quote from: Musicforawhile on 09/11/2014 21:25:56
Quote from: dlorde on 09/11/2014 20:42:06

3 - it makes no difference whether the numbers have come up before or are randomly generated. Intuitively, one feels it should make a difference, just as one feels that after tossing a coin 10 heads in a row you're more likely to get tails. Intuition is wrong about this.


My mind can't accept this, not at the moment anyway. And I think that if all the mathematicians here weren't under the gaze of their colleagues, academic supervisors, and potential academic funders then you would all go for Number 2. But you don't want to be seen as woolly headed and led by your instinct rather than your rationality. In the same way I am sure many scientists wouldn't want to admit their secret agnosticism or prayers to god.

If you're not going to believe us if we say "3," then what is the point of asking the question in the first place?

10
That CAN'T be true! / Re: Are Einstein's theories obsolete?
« on: 07/11/2014 17:39:45 »
Quote from: NUFOIB on 07/11/2014 13:07:30
Sorry, I'm not into theories.

I can kind of tell.

The absolutes you want are simply not available to any empirically based system of knowledge. Science is nothing if not empirical. You might be disturbed by the fact that we never do "better" than "This theory has faced test after test and never been disproven." I think the track record of what humanity has learned in the past few centuries with this "imperfect" level of certainty is evidence enough of its utility.

Of course, that notion of mine is another non-absolute (I don't even pretend it reaches the level of a theory), so I expect that it is in your eyes at least equally invalid as the products of science.

11
Physics, Astronomy & Cosmology / Re: Thought experiment - Tethered galaxies - the rope
« on: 10/09/2014 15:05:10 »
Quote from: LazyJones on 05/09/2014 18:58:50
non-elastic rope

A non-elastic rope is a physical impossibility as well. For the rope to be truly non-elastic would require that the forces holding the rope together be able to communicate changes at one end of the rope instantaneously to the other end of the rope. In reality, the forces can not communicate change faster than the speed of light.

12
Physics, Astronomy & Cosmology / Re: Are random events down to luck?
« on: 30/07/2014 18:31:12 »
Quote from: allan marsh on 27/07/2014 23:19:20
tossing a coin a few times has a random event chance. tossing the coin many times averages out the random chance to evens.

This sounds pretty close to the gambler's falacy, so let's be precise. Every toss of a coin is independent of every other toss. If the coin is fair, that means there is no bias of heads over tails or vice versa. That's far from the same as saying that in the long run you shouldn't get more than one than the other.

Suppose you toss a fair coin an even number of times, N = 2n. If we only care about the number of heads and tails, it is true that the most probable outcome is that H = T. However, as N gets bigger, the probability of that specific outcome gets smaller. If we consider the difference between the number of heads and tails D = H - T, and we average the absolute value of that difference over all possible outcomes, |D|avg gets bigger as N gets bigger. The absolute value is important, because more heads than tails is just as likely as more tails than heads, but the more times you toss, the bigger the range of likely differences becomes.

Now there is a sense in which the results of the tosses "even out." While |D|avg gets bigger, |D|avg/N gets smaller. So if we imagine a game where I keep all the coins that come up heads, and you keep all the coins that come up tails; the longer we play, the bigger the margin that one of us is winning by is likely to become, but the smaller that margin becomes compared to the nearly equal amounts that each of us has received.

Quote
so do short term random events have a different rule as i seem to be lucky. of course in the universe i presume someone else doing the same test must be equally unlucky??

If we are talking about something like tossing coins, each toss follows the same rule, just as I said above. A long run of coin tosses doesn't follow any different rules that a short run. The difference between what we expect (in the mathematical sense) from a long run and a short run is entirely down to the fact that a long run has a different set of possibilities available to it than a short run does.

Since I don't know what you mean by "lucky" it's hard to answer more precisely than that. I will say, however, that people are really lousy at recognizing true random behavior. If you toss a coin a large number of times and write down the results of the tosses, not only is it likely that you won't have exactly the same number of heads as tails, but you will probably have runs of heads and runs of tails that will look too long. They're not. We intuitively think that the heads and tails should be evenly distributed, but there are far more ways that you can come up with clusters of the same result consecutively than to have them spread out. If you have normal intuitions about probability, the collection of possible outcomes that look "lucky" to you is actually far greater than the collection of outcomes that look "normal" to you.

13
Physics, Astronomy & Cosmology / Re: radioactive decay?
« on: 10/07/2014 15:02:48 »
Quote from: allan marsh on 10/07/2014 10:49:38

SO
without using the word probability,!!   please would someone explain the mechanism that determines , WHEN the atom goes pop??

No one knows an answer to that. I will point out that the way you phrase the question presumes that such a mechanism exists and that there is a definite time when a specific nucleus (not atom, to be pedantic) will "go pop." Modern physics always talks about probability because there is currently no evidence to suggest any mechanism behind quantum phenomena like radioactive decay that makes them actually deterministic.

That doesn't mean that such a mechanism doesn't exist. It does mean that physicists are going to want any proposed mechanism to be testable. It's also a pretty safe bet that if a mechanism exists, it's going to be a pretty strange one.

14
Physics, Astronomy & Cosmology / Re: What do you think of my quantum power idea?
« on: 09/07/2014 14:51:48 »
I agree with JP. The article does not describe what you want for your quantum power idea, which would be some sort of persistent entanglement. Entanglement as it is theorized and has ever been observed only lasts until the first measurement is made.

Particle A and B start in an entangled state, but we know nothing else about them. We measure particle A, and the entanglement determines what the result must be if we perform the same measurement on particle B. However, if we do something else to particle A after the first measurement, it will have no effect on particle B.

The article describes those initial measurements working when the particles are the two electrons in a Cooper pair. It does not describe changing the state of the first electron after measuring its state initially.

An experiment where manipulations of one particle after an initial measurement managed to change the state of a distant entangle particle would receive both far more hoopla and far more skepticism than shown in that article because it would run completely counter to the predictions of quantum mechanics.

15
Physics, Astronomy & Cosmology / Re: how many of you believe that a vacuum can have temperature?
« on: 24/06/2014 15:01:40 »
Quote from: yor_on on 24/06/2014 11:37:03
Only in relation to matter, as I think, Evan.

What do you mean by this? Specifically, when you say that vacuum only has a temperature in relation to matter, how do you view that as different than the temperature of any other physical system?

16
Physics, Astronomy & Cosmology / Re: Can electromagnetic fields be generated where there is no movement involved
« on: 20/05/2014 15:10:52 »
OK, lets look at this in detail.  A charged particle has an electric field.  This is true in all frames of reference.  If you look at the charge particle from a frame of reference where it is in motion, it will also produce a magnetic field.  The electromagnetic field is transformed between relatively moving frames of reference.  However, when you take this into account with everything else that gets transformed, observers in the different frames of reference will still have consistent observations.

If we have two particles with charges of equal magnitude but opposite sign, if we look in the frame of reference where they are motionless (or if they aren't constrained where their motion is solely due to their mutual attraction) the electric field will be very weak far away from the particles because their effects cancel.  If we look at them in a frame where they are comoving, they do produce a magnetic field, but again a very weak one because we now have two opposite "currents."

If we have charges of the same sign, the electric field is stronger because the effects don't cancel and the magnetic field is also stronger because the currents also have the same sign.

If we are asking whether the two particles can fire the trigger, the easiest way is to figure out what would trip it in the triggers rest frame and then figure out what field the particles are producing in this frame.

If we then change our frame of reference, it will be true that the electromagnetic field of the particles will be transformed, but we need to remember that the trigger is now in motion as well and we need to consider how the electronics in the trigger behave moving through the new electronmagnetic field.  We can't act as if it is stationary in that field, because it isn't.  If you crunch through the details, there will be no paradox.  All observers will agree whether the trigger should be tripped or not.

17
Physics, Astronomy & Cosmology / Re: direction of Torque
« on: 07/05/2014 16:02:49 »
There isn't a physical reason.  That's what JP was saying.  It is a convention that the torque direction is the way it is, but it is an arbitrary convention.  If we used the opposite convention, the physics would be identical.  There is no experiment to determine that the right hand rule it the correct way to describe torque and that the left hand rule is the wrong way.  This is true of all quantities of angular motion (angular velocity, angular momentum, etc.) not just torque.

Take the example of the rotation of Earth.  Viewed from above the North Pole, Earth is rotating in an anti-clockwise direction.  Following the right hand rule, the angular momentum vector of Earth is pointed "north."  If we used the left hand rule, we would just be describing the same rotation of Earth with a vector pointed in the opposite direction.  Nothing physical changes, just the mathematical convention of how we describe the physical reality.

18
Physics, Astronomy & Cosmology / Re: Has Einstein been misrepresented?
« on: 06/05/2014 15:10:44 »
It may flatten, but it will not be perfectly flat.  Sure, over short distances it may need an impractically high level of precision to detect any tidal gradient, but that's true near Earth's surface as well.

19
Physics, Astronomy & Cosmology / Re: Has Einstein been misrepresented?
« on: 05/05/2014 19:19:08 »
Quote from: jeffreyH on 05/05/2014 17:10:59
However in the case of a cubic object this will not be true.

Why not?

20
Physics, Astronomy & Cosmology / Re: does plasma happen in soild state
« on: 30/04/2014 16:36:45 »
Generally, the word plasma is reserved for an ionized gas. In this case the electrons are not bound to anything.  While the conduction electrons in a metal are not bound to a single atom, they are still bound to the bulk solid.

Really, this is an accident of language.  Plasma could have been defined broader than it is.  Understanding the behavior of an ionized gas provides little insight into the behavior of a solid conductor, so the narrower defintion is probably going to endure.

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