PlaneShift
Fan Area => The Hydlaa Plaza => Topic started by: zanzibar on February 05, 2009, 01:20:11 pm
-
E=mc^2
The energy in a nuclear reaction comes from the conversion of mass into energy.
Where does the mass come from? Is it a conversion of relative mass? Are massive particles disappearing while massless particles are being created? Is it the bonds between particles that are being converted?
-
This might help you zanzibar http://en.wikipedia.org/wiki/Nuclear_reaction
Though I do not believe we should be doing your homework.
-
Hello
i think the "mass" come from this place
http://en.wikipedia.org/wiki/Big_Bang
-
Also recommendable literature:
(http://www.bookdepository.co.uk/RESOURCE/MEDIA/IMAGES/bookcovers/Original/BookCovers13/978/0/5/9/3/9780593048153.jpg)
According to this, mass is a property of the matter, mainly of the hadrons it is made of, and gravity is the bending of the space due to the mass.
Being hadrons, the elements of the atoms exist within the range of the strong and weak nuclear forces.
You could even say, mass is the "manifestation energy", from some point of view.
-
It is the strong nuclear bonds being broken in a nuclear (fission) reaction that produce the energy I thought.
-
The total mass of the particles after fission is slightly less than the total mass of the particles before fission. The missing mass is what was converted into energy.
E (energy formed during the reaction - fission or fusion) = delta m (change in mass) x c2 (speed of light squared)
-
Mass and energy are illusion, we are but characters acting on the holodeck.
-
Mass and energy are illusion, we are but characters acting on the holodeck.
Good post,
Zanzibar, how can you continue to to see the world as real if the self that is determining it to be real, it's intangible ?
-
Where does the mass come from? Is it a conversion of relative mass? Are massive particles disappearing while massless particles are being created? Is it the bonds between particles that are being converted?
It's slightly different depending on whether you're talking about fission or fusion (they are opposites reactions, pivoted around Iron I believe).
For fission; When you split an atom there are several products made; (usually) two smaller atoms, some neutrons and then energy if the atom is Iron or heavier. This energy is from the difference between the mass of the original atom and the combined masses of the smaller atoms and neutrons produced. That energy comes from the nuclear bonds that were holding the particles from the original atom together.
For fusion; Up to iron at least there is energy given off. This energy is again from the bonds that were holding the particles in the two atoms together. When the atoms fuse, any extra energy that's not required to create the new atom is released - this varies depending on how many neutrons are also released and the size of the atoms being fused.
Maybe a better answer to your question is; that 'mass' doesn't come from anywhere. There's no conversion between mass and energy except as a equivalence on paper, they're the same thing.
-
Where does the mass come from?
E=mc²
The mass might come from here:
Massless gluons
Massless up&down quarks
Nothing else
---------------------------------------------- +
= Mass
http://www.youtube.com/watch?v=ECkG_JdodMA for further reference on QCD
But I still remain on my Prolix idea that "Mass and energy are illusion, we are but characters acting on the holodeck."
-
It was a very trite and probably erroneous parsing of the Holographic Principle (http://en.wikipedia.org/wiki/Holographic_principle) in regards to quantum effects associated with black holes.
How that squares with the possibility of Naked Singularities (http://en.wikipedia.org/wiki/Naked_singularity) is beyond me but there did happen to be an article in the latest issue of Scientific American which bought this week for some strange uncommon reason.
-
Is the number of protons and neutrons different before and after the reaction?
-
Mass is just a specific "solid" kind of energy.
Protons and neutrons are not distinct, a pure neutron has a half-life period of just about 11 minutes - only the interchange of quarks with protons in the neighborhood gives them a pseudo-stable appearance.
Don't think of "elementary particles" as solid spheres like marbles. They are rather a streaming concentration of energy. Those which cause gravity by distorting the space around them have a mass.
Well ... according to the theories founded by Hawking and colleagues. Who knows the whole truth about the universe? One who made it - if at all.
BTW: I dare you to think in 10 dimensions (http://www.chilloutzone.de/files/09012501.html)...
-
The energy in a nuclear reaction comes from the conversion of mass into energy.
Wrong. It comes from ME.
/me cackles maniacally, and detonates. *
-
Been through Nuclear Prototype school, been certified as a nuclear reactor Operator AND Nuclear reactor techician by the NRC.
A lot of good theory mentioned above. Remember C^2 is a really big number, so any easily measured amount of mass converted directly to energy would be, well, hard to measure, since it would be really REALLY hot, melting your tiny little scale. ;D
in basic nuclear reaction, you have an unstable element (uranium for example, not iron) which will decay on its own, releasing heat and nutrons (and decay daughters, which further decay, ususally faster, adding heat and other radiation, but we will ignore that for now). You have a material to absorb the neutrons that are produced, and reaction stays slow. as you remove the dampening material the neutrons begin to collide with the uranium, making the half life thatis normally around 700 million years to become moot, releasing more and more neutrons.
This energy release is primarily from the kenetic energy of the fission fragments.
You could just as well, and perhaps more interestingly ask, since photosynthisis is transfering light energy into chemical energy, how come we can not reliably and repeatably measure the increase in weight in a closed system where only light is added (though I believe it has been done, within an expected range) . (weight of plant tissue is acounted for by water and carbon dioxide it absorbs) Again, E-mc^2 is a nice tool, but hard to meausre weight loss with energy use in a real world setting.
Even metabolising glucose and transfering energy from ATP to ADP in a human body uses mass, thoretically, but the effoct is insignificant compared to the amount of water, and even the amount of salt you may lose during such a test.
So, to wrap it up, do we create and destory mass, sure. press the "I believe" button if you like. And if you are a theoretical physicist, you may even crunch the numbers. But when you realize that the amounts discussed are less than the significant digits used in most calcuations, most tend to disregard that minor effect.
We do not run out of Uranium because it loses mass, we run out of uranium (at a level that promotes being critical in the same configuration as it being safe to use when start reactor for first time) because it decays into decay daughters.
Like asking about the energy/mass relationship of E=MC^2 relationship of gasoline in a car engine. You can not weigh your gas, and crunch the numbers and figure one gallon of gas will take you 1,000,000,000,000 miles. virtually all the mass leaves the tailpipe. I hope that makes it clear, without ruining any attempt and being somewhat humorous. :D
-
So... the number of protons and neutrons before and after uranium decays, is it the same?
-
So... the number of protons and neutrons before and after uranium decays, is it the same?
Yes
(I don't believe there is any beta decay, but I could be wrong)
-
An interesting piece of info that I came across in a recently published paper (no link sorry) is that something like 70% of the mass of a proton (I think) is actually the kinetic energy of its constituent quarks.
-
yes, that is called the conservation of nucleon number. of course they are not all attached to the decay daughters, some are "running around" but they are neither created or destroyed.
BTW, I googled your last question, a decent explanation: http://physics.bu.edu/py106/notes/RadioactiveDecay.html (http://physics.bu.edu/py106/notes/RadioactiveDecay.html) note the discussion on mass defect. it exists and is measurable, but is a relatively small amount. check out the link, i think that answers your question without me personally releasing any classified information.
it is a lot like spoilers on this forum, I can link to information I know, even when i can not reveal it myself. For example i can not tell you much about my ship, even though it has since been decommisioned, but Jane's Fighting ships has a lot of information that would send a classified person into the brig, if they were to release it themselves.
-
beta decay started to bug me so I looked it up.
From wikipedia-
Since the nuclei that can readily undergo fission are particularly neutron-rich (e.g. 61% of the nucleons in uranium-235 are neutrons), the initial fission products are almost always more neutron-rich than stable nuclei of the same mass as the fission product (e.g. stable ruthenium-100 is 56% neutrons, stable xenon-134 is 60%). The initial fission products therefore may be unstable and typically undergo beta decay towards stable nuclei, converting a neutron to a proton with each beta emission. (Fission products do not emit alpha particles.)
- so I was kind of right
The fission products have the same number of total neutrons and the same number of total protons, but the fission products may undergo beta decay converting neutrons to protons. But as Bamko pointed out the total number of nucleons (neutrons + protons) will always remain the same
-
I think it would depend on the relative strength and duration of the reaction. I can imagine a reaction of such power that at least some of the atomic constituents were broken up into their quantum components. These quantum particles might well recoalesce or recombine into atomic particles quite quickly but that would just be deceptive to the casual observer.
-
can not see it, so it must occur.... ;D
i really think this is being over-thought. Almost all the energy comes from the kinetic energy of the fission products in the fission and/or alpha decay of uranium.
we can wax poeticaly about mass loss in any reaction, chemical or nuclear, but that is "over-nukeing it" And this is from a former "nuke" so I know what that looks like. :woot:
Most do not consider the effect of mass "creation" by sunlight in a plant, because it does not create any new protrons or neutrons, and the mass gain is so insignificant compared to the amount of carbon gain by respiration.
Where does energy come from in a nuclear reaction? From the kinetic energy of the products, mostly.
But can we spin out wheels and make this into "the philosophy of matter"? sure we can. We already have.
but then, how do you know matter even exists? :P
-
Most do not consider the effect of mass "creation" by sunlight in a plant, because it does not create any new protrons or neutrons, and the mass gain is so insignificant compared to the amount of carbon gain by respiration.
Urr, there is no mass 'creation' in light photosynthesis. The light is used to split an electron from chlorophyll (which it regains later from water), so there's no energy to mass done here.
Also, the mass 'loss' in a nuclear reaction is a fundamental component to the process, the discovery of it was quite major in the field. So I don't know what you're talking about when you say it's poetic waxing.
-
Almost all the energy comes from the kinetic energy of the fission products in the fission and/or alpha decay of uranium.
...
Where does energy come from in a nuclear reaction? From the kinetic energy of the products, mostly.
The added kinetic energy of the fission products is the energy of the missing mass.
-
I think it would depend on the relative strength and duration of the reaction. I can imagine a reaction of such power that at least some of the atomic constituents were broken up into their quantum components. These quantum particles might well recoalesce or recombine into atomic particles quite quickly but that would just be deceptive to the casual observer.
Is this just what you think, or are you citing something?
-
What I think of course but if you consider what might happen in the collapse of a supergiant star the forces are so great that the streams that shoot out from the event horizon are likely enough to break up the atomic particles. Now once you get into quantum particles it gets a lot more dicey and my understanding is far more limited. I am a lay person and not a scientist of any type. Certainly what happens within a singularity is a subject of much debate. From what I understand, large stars that go nova become neutron stars, huge ones become singularities where even the neutrons break down.
At the quantum levels I think some of the particles are considered massy while others not so much.
Nobody knows what really happens.
Anyway my imagining does not necessarily match reality :)
-
What I think of course but if you consider what might happen in the collapse of a supergiant star the forces are so great that the streams that shoot out from the event horizon are likely enough to break up the atomic particles. Now once you get into quantum particles it gets a lot more dicey and my understanding is far more limited. I am a lay person and not a scientist of any type. Certainly what happens within a singularity is a subject of much debate. From what I understand, large stars that go nova become neutron stars, huge ones become singularities where even the neutrons break down.
At the quantum levels I think some of the particles are considered massy while others not so much.
Nobody knows what really happens.
My question was whether or not you were citing from something you've read, or if it was just your speculation.
Anyway my imagining does not necessarily match reality :)
Exactly.
-
Well to be more specific I was relating my poor understanding of vaguely remembered reading of various articles in popular science magazines. Particularly Scientific American which I buy maybe once a year or so. I think the last edition I bought talked about this stuff, I do know it talked about multiple universes as well. Certainly not everything you see in such a magazine is definitive and sometimes turns out to be complete speculation.
-
Well to be more specific I was relating my poor understanding of vaguely remembered reading of various articles in popular science magazines. Particularly Scientific American which I buy maybe once a year or so. I think the last edition I bought talked about this stuff, I do know it talked about multiple universes as well. Certainly not everything you see in such a magazine is definitive and sometimes turns out to be complete speculation.
Ah. If you happen to find the article you were pulling ideas from, I'd read it.
-
Well this months (feb09) Discover magazine has an article "The Violent Birth of Stars" and another "Quantum Secrets of Life", This months Scientific American has "Naked Singularities" The older magazines appear to have been recycled but you ought to be able to find them in your local library. You might try a search (http://www.sciam.com/search/index.cfm?cat=Physics&i=1&q=string+theory&submit=submit&submit.x=5&submit.y=1&u1=q&u2=cat) of Scientific American's website. Discover magazine has a website (http://discovermagazine.com/) too
I'm sure most of the other science magazines have stuff online as well but the hard copies probably have more stuff in them.
-
I'm really just interested in your claim that nuclear reactions create plasma. I'd like to see a source so I know what to believe.
-
I never said anything about plasma, (http://en.wikipedia.org/wiki/Plasma_(physics)) that is a subatomic state of matter not a quantum phenomenon. Elementary particles (http://en.wikipedia.org/wiki/Elementary_particle) are smaller than the protons/electrons/neutrons and can be produced in an atom smasher like the Large Hadron Collider (http://en.wikipedia.org/wiki/Lhc). All I was saying was that if humans can produce these quantum particles artificially through the destruction of sub-atomic particles then it is not too far-fetched to think they can be created, or rather exposed as they already exist, buy natural means. I am not at all certain that they cannot be reduced beyond the quark, strange or whatever level as it has been shown time and again that existence is far more complex than previously understood. Elements were supposedly indivisible until atoms were discovered and they were supposed to be basic until quantum particles were produced. Given the generally fractal nature of reality as we know it I think I hear a Who, eh Horton?
-
About the "mass creation via photosynthesis":
Ah, therefore it is called "power plant"... :D
[ Plant: a) lifeform; b) factory ]
-
The nuclear reaction (fusion) which occurs in stars is the inverse reaction of what we've been discussing here (fission).
It's very confusing when the topic keeps changing in random directions :P
Fusion reactions can 'create' subatomic particles called neutrinos, but not quarks (which make up protons and neutrons).
The difference between the LHC and the Sun there is that the former focuses a lot of energy into a small space, the latter just releases a lot of energy. The density of the energy makes a big difference.
Electrons are an elementary particle (lepton family) btw.
As for plasma - usually plasma is needed to start a nuclear fusion reaction, it's not created as a by product of it.
It'd be more informative if people didn't speculate completely devoid of fact. ;) Not that speculation is a bad thing.
-
As long as the mankind only knew electrons, protons and neutrons, those were the elementary particles.
When quarks got discovered, protons and neutrons were no longer elementary. Electrons are still elementary for us, as long as noone discovers that they may consist of smaller units.
As far as I remember, it is convenient for mathematic models and for the Grand Unifying Theory, to interpret matter and particles (quants) as a special meta-stable form of energy. Forces are interpretable as exchange of quants ... so far with the exception of gravity, which appears as space distortion instead, supporting the absence of "anti gravity" forces.
Until contrary experiments prove the current theories wrong...
-
Science is confusing.
-
And imagine ... in medieval times, most people learned in their whole life as much as today you can learn from one daily issue of a newspaper.
-
Most do not consider the effect of mass "creation" by sunlight in a plant, because it does not create any new protrons or neutrons, and the mass gain is so insignificant compared to the amount of carbon gain by respiration.
Urr, there is no mass 'creation' in light photosynthesis. The light is used to split an electron from chlorophyll (which it regains later from water), so there's no energy to mass done here.
Also, the mass 'loss' in a nuclear reaction is a fundamental component to the process, the discovery of it was quite major in the field. So I don't know what you're talking about when you say it's poetic waxing.
Been a few decades, but I remember (hopefully accurately) that when the formulas are tracked in chemical reactions, in photosynthesis for example, there would be nanoscopic increases in the atomic mass of the resultant molecules when energy is added to a system, and a loss when energy is removed. of course we see this as the chemical "energy" of the bonds, but, as I understand it, this energy is stored as mass. Of course I am talking about even smaller masses. Obviously the amount of energy stored in a glucose molecule, is surely many magnitudes smaller than the amount of energy that is released from the decay of a Uranium atom. I would have to more than a cursory look to find this, but I am pretty sure that it supports my point. We do not say "wow, we turned mass into energy" but we know we do not create it from nothing. So saying a nuclear reactor gets power from the mass that is lost, (though it no net loss of particles) may be accurate, but we in the industry point out that the power comes from the kinetic energy from the fission fragments. See http://en.wikipedia.org/wiki/Uranium-235 (http://en.wikipedia.org/wiki/Uranium-235)
Just as kinetic energy is transferred to potential energy on a roller coaster, and back again, I believe that chemical potential energy is not magically held there by the fact that chemical bonds use energy. Some use energy (endothermic) and some create energy (exothermic). I would bet that the bonds that, when broken, releases energy, that potential chemical energy could be measures as an increase in mass. I also bet that it would be very hard to measure it, as we are talking the edge of theory here, but that is what I meant. the increase in weight of plant tissue is 99.999999? accounted for by CO2 and water and other stuff, so talking about the energy stored in the chemical reactions is a small portion. (I do concede it may not have been a good analogy.... I was typing it while a co-worker was talking to me about his plans for the weekend..hehehe)
Same with U-235. people talk about the weight loss like the reactor is going to get lighter as we run it. sure, in theory, but the fact is, the weight loss is best pondered by physicists. When I stood for my NRC (Nuclear Regulatory Commission) Board, if I had said "the energy comes converting mass into energy" I would of been booted out of the Board. So forgive me if I do not concede the point quickly.
to wrap it up, that is like, to me, when you are asked "why does this rice taste sweet?" saying "because you have sensory organs in your mouth that can sense the presence of sugars, and your brain interprets these sensations as "sweet"." instead of saying "oh, I mistook the sugar for salt, so it has a little sugar in it". ;D Both are true, but what answer is correct? depends on our intrepretation of what was really asked. and that might be even more hard to guess.
-
Well - so we presented a wide range of possible answers. Pick the one that suits best your expected meaning of the question...
-
I pick these :D
The total mass of the particles after fission is slightly less than the total mass of the particles before fission. The missing mass is what was converted into energy.
E (energy formed during the reaction - fission or fusion) = delta m (change in mass) x c2 (speed of light squared)
The fission products have the same number of total neutrons and the same number of total protons, but the fission products may undergo beta decay converting neutrons to protons. But as Bamko pointed out the total number of nucleons (neutrons + protons) will always remain the same
The added kinetic energy of the fission products is the energy of the missing mass.