I get lots of great questions from experts as well as novices. The problem with expert questions is that they often take a lot of space to answer, and they make the discussions unreadable for the less knowledgeable. Since my main purpose is to serve the public, not the physics community per se, I’ve decided to direct particularly technical questions that I can’t answer in a few words to this area.
First Time Visitor?
This site (new and still growing rapidly) will eventually cover many topics in science, but currently focuses on particle physics in particular. My aim is to serve the public, including those with no background knowledge of physics, but also those who have been keeping track of the latest in particle physics news. If you're not yourself an expert, you might want to click on "New? Start Here" or "About" to get started.
If a Higgs particle is produced in a proton-proton collision, an LHC detector might infer what you see here. The two red blobs indicate deposits of energy left by particles of light (photons) that are the remnants of the disintegrating Higgs.
-
Recent Posts
Categories
Popular Pages
Another question regarding the Higgs field. The Higgs field is all pervasive throughout the universe, but I assume we cannot detect our motion through it. Otherwise, it seems masses would change value slightly as the earth revolves around the sun. Is the reason for this because the Higgs is a scaler field and because the spin of the Higgs particle is 0?
This question is in regard to the paper by Andrew Cohen and Shelden Glashow mentioned in your Oct 6 article titled “Is the OPERA Speedy Neutrino Experiment Self-Contradictory?.”
In the comments, Lee Smolin said that “assumes that the relativity of inertial frames is broken, so there is a preferred frame.” If so, why are the results of the paper thought given the weight of a “refutation”? The assumption of a special frame of reference seems (to me) as extraordinary as what it claims to refute,
As a layman, I thank you for this opportunity to ask this question which has been really bugging me!
The authors said “refute”, referring to a particular interpretation of the OPERA experiment. I myself wouldn’t have said “refute”, but that’s just a wording issue; the physics result is the interesting part. Their work makes clear that a very large class of modifications of Einstein’s theory would not be able to explain OPERA. I would say it makes OPERA’s result less plausible — but it is still just an argument. Until the OPERA experiment is shown to be wrong (either a mistake is found in OPERA’s technique, or multiple and/or better experiments contradict the result) the case remains open.
Sir, could the ‘indication’ of the higgs particle recently announced just in fact be confused with a di pole fermion – mimicking the higgs? Secondly, in the early stage of evolution ( ‘so called’ – linear expansion of the universe ) when no mass existed whatsoever ( inc Baryons ), does the case and argument for STR and GTR still hold true? As soon as mass appeared in this offspring ( recycled ) universe we now try to understand ‘everything’ centred around it’s existence – and the tiny parts of it. If the case for STR and GTR do not hold true in a massless space – then we are now somewhat confused? Suppose for one moment that Newton’s intuition is correct that the universe does form a background absolute and may be thought of as a separate entity – which just so happens to have mass occupying it + black energy etc. Let’s for argument sake remove all the mass from the universe by virtue of pure mathematics. What do you make of the universe then? Surely, it is still expanding with nothing in it! Moreover, let’s think of this huge void with a zero dimension where time is homogenous. ‘Zero dimensional space’ – papered by the german physicist late 19C Felix Hausdorff which has much relevance to consideration to fractals and shapes in nature. Could it be that the void of the universe is actually a pseudo space in the sense that it is not composed of Euclidian 3 spatial dimensions. If this could possibly be true and if the concept of time is homogenous – then all kinds of interesting notions are possible. Starting with Planks constant. LHC is in search of the Higgs because it causes other particles to bequeathed mass. However, If the universe void does have a zero dimension and is expanding at the rate of 300,000kms then once again we can change this value in Planks constant ( hypothetically ) in doing so the value of ‘C’ is immediately changed. In doing this we immediately alter the cohesive available frequencies in any of the standard model particles. The outcome of this revelation would be that all atoms would dissociate and be take to to a new low Zero Ground State – or alternatively a higher one depending upon the new hypothetical value given to ‘C’. Also, even more incredible would be the realisation that the ability of a photon to reach 300,000kms is not determined by itself. The ability to achieve this velocity is in fact determined by the orthogonal opening framework of the zero dimension of the universe. In the sense that for any object to move it must have a dimension to move into. The available mechanism providing this is Newton’s background absolute – which has been ignored since Michelson-morley/Eistein & Minkowski. It is creating ‘New Space’ second for second in every direction – not the thought of etheral wind! Thanks for your time in reading and considering this. From a book called Absolute Relativity Theory of everything.
In 1966 — or perhaps a year earlier — one of my undergraduate students in the physics department of Queens College (CUNY) had entered a paper into the school’s science publication; “The Nucleus.” Its title was: “A NON-RELATIVISTIC MODEL OF DISTURBANCE PARTICLES.” None of our faculty had ever seen the term: “disturbance particle,” used before and the paper gave rise to a great deal of heated argument within the physics department, and even beyond it. It transpired that the student had ‘invented’ the term along with a model of something which he referred to as a “free energy field” capable of supporting disturbances which caused changes in local energy density. The student posited the existence of certain “Critical Numbers” which bore the units of energy density and which served as predictors of just how a locale of the energy field would behave as a function of its density. Above a certain critical number — his theory predicted — the locale would behave as a ‘particle.’
One of the young student’s professors, Dr. Banesh Hoffman, pointed out that the proposed model was “attempting to resurrect the concept of an aether which we all know is impossible,” and that “his model does not transform relativistically.” When I replied that it was, after all, a “Non-Relativistic” model, Dr. Hoffman simply shrugged his shoulders, smiled, and asked: “What on earth does that mean?”
It may be that, now, with the advent — possibly — of particles which travel faster than the speed of light, that young student’s model of “Disturbance Particles” may, in fact, mean something after all. Perhaps we should take another look at “The Nucleus” publication which bore that paper.
M.C.
Professor,
this has been dwelling on my mind for quite sometime now. I am currently enrolled in college and there have been a few things on my mind that I have tried figuring out on my own as well as discussing with my peers. I have asked numerous science majors this as well and have gotten mixed responses. I have heard talks about whether teleportation is possibly these days and we both know it is not. Well, not with OUR current technology anyway. But if technology wasn’t an issue, it would most certainly be possible. I sincerely apologize for rambling on quite a bit in this letter to you, so I will quickly get to the point. I am sure that you are well aware that if a person were to be teleported from a certain point (lets say point A), their atomic structure would be broken down and then the data of that person (memories, personality, etc etc etc) would be transmitted to point B. I am well aware of quantum entanglement and whatnot. Also, the argument of the soul and religion cannot be used as part of this due to the numerous amounts of complications that they may cause. Now as for the new person that was constructed at point B, the atoms would be new ones, therefore making a new person. But, I decided to take this argument a step further. If the SAME atoms were transported from point A to point B, would it still be the same person? Or would it be a clone? Many people have said that it would be the same person, due to the building blocks being the same. However, there is something that still bothers me. When the bonds of the atoms are broken, the atoms go back to their original state. I.E. carbon, oxygen. And I would like your opinion on this, if the all of the same atoms were put exactly back into place as they were before the person was atomized, would it be the same person with the SAME consciousness, or a new person with identical personality, memories, etc etc etc with a NEW consciousness as well? I look forward to your response(s). Thank you for your time and consideration.
You have asked a classic philosophy/physics question, one that has been asked a million times before. Including by me, when I was your age. [Anyone who has watched Star Trek or its predecessors raises this question.] I am afraid that no one knows the answer, and it isn’t obvious the question can be answered in the next few decades or even centuries. Or perhaps ever.
Consciousness is very poorly understood, in general. Moreover, it has two very different aspects. The *appearance* of consciousness is still not something well comprehended, but at least one can try to study it using investigations of the brain: one can ask how the brain allows us to make choices, for instance. That’s an active area of research in neuroscience. But worse — and this is crucial to the question you are asking — the *experience* of consciousness isn’t even obviously something accessible to scientific inquiry. Suppose you made a copy of a person and that person acted as though they were the same person as before, and claimed to have the same consciousness as before. How would you check that person’s claim? How would you know if that person was mistaken in his or her belief? What experiment could you do?
Similar question (addressed, again, by many science fiction authors, and numerous philosophy classes); suppose all your neurons were encoded somehow in a computer, with all the connections and electrical activity repdrocued through software. This system would then act as though it were as conscious as you. But would it be conscious, or not?
Let these questions dwell in your mind, because that’s where they belong. Perhaps you will someday have an insight into how to think about them. I certainly haven’t had one.
Lurk on this blog a great deal. Great job Dr. S. I am a physical chemist turned neuroscientist and hear these questions a great deal. I find that even otherwise objective folks (including scientists) can get bogged down in philosophical (and often, pseudo mystical) speculations about consciousness. Consciousness (which is really a perception) can be operationally defined (although there is always someone who will aver that the definition is not *real* consciousness) and examined objectively in the laboratory, both behaviorally and with neuroimaging. Questions about teleportation, computer cloning, etc. have two kinds of answers. The first is that Star Trek style teleportation and exact computer duplication of a brain are fantasy, not science. Consider the second scenario. What would it mean to “encode all your neurons in a computer”? Presumably this would mean constructing a model of the brain using some sophisticated combination of hardware and software. To what level of fidelity would we make our model? Not, clearly, at the level of elementary particles. Although the brain is collection of quarks and electrons, it seems that a model developed at this level might strain our current computing power. How about at the level of neurons? We could imagine creating a bunch of subroutines that model, say, an excitatory glutamatergic neuron’s hundreds of synapses, multiple neurotransmitter and neurohormonal receptors, it’s biochemical interaction with the surrounding astroglia and have the subroutines output a firing rate that models the release of glutamate from the neuron’s axons. We make similar models for each kind of neuron and glial cell in the brain, and put them together in a topographically organized fashion that maps to how one particular brain is put together. We’d have to model the brain’s continual remodeling that is necessary for memory and learning, model inputs from sensory regions that are greatly responsible for the brain’s architecture, model the feedback from possible motor movements, accurately model all the connections between neurons that have resulted from however many years of experience our potential computer clone might have had, and so on.
Is there a layer of abstraction at which it makes sense to talk about uploading a person into a computer? I suspect not, because when I follow the logical path to what such a statement might actually entail, it appears to be practically, if not intrinsically, impossible. it is quite possible to construct toy models of brain function and they can tell us a lot about how the brain works. The question of whether a machine can develop consciousness is a different issue (it’s clearly true, our brains are machines and they are conscious, but this question usually refers to machines designed by humans). There is also the problem of the computer person’s body. Our brains live in the rest of our bodies and our brains’ experiences are predicated on how our extracerebral self gathers data. I suppose we could model a body, too, and how it reacts motorically to the external world. But you see my point.
“But”, it is often said, “just suppose we *could* duplicate you exactly, either in a computer or in the flesh. Well, you’d have two people who were quite familiar with one anothers’ favorite drinks and intimate details of their past lives. They would certainly be more similar than identical twins, but they would be separate individuals, who would, over time, slowly diverge in terms of experience and behavior. As there is nothing magical (or supernatural) about what makes someone a person, those duplicates would have all the characteristic of birthed and grown people.
A somewhat long post (and yet not long enough) that primarily argues that discussions of teleportation and personality uploading tend to ignore the real problems associated with actually performing the task and simultaneously somewhat mysticize the hypothetical result.
Next time, I’ll ask how spontaneous symmetry breaking is like a phase transition (to which it is often compared).
When you say “consciousness” , it seems as if you meant to say the “soul” . As physical consciousness is the same as the persons working memory (it is the open interaction of various sections of your brain using stored chemical memory in your mind when the neurons begin transmitting all over you become conscious as a result of new experiences your consciousness changes and so do you and when you go to sleep or are knocked on the head like Tintin often it’s similar to miniature death as your brain loses complete consciousness . So as far as your question goes
1) Yes the persons soul ought to be transported to point B [ that is if he can be kept alive] and he would be the same if the same atoms were used while a new soul /[he'd be a clone] if the original was terminated and a copy from the original data was created at pt. B.
2)they would both have the same consciousness the fraction of a second after transportation but person before (proper transport or cloning) and person after (proper transport or cloning) would be as different from each other as you are from yourself a second ago[always changing]
That’s why i’m sure it was federation rule to use the same stuff rather than other stuff (the Vulcans would never except the kill original then clone yourself method due to their Katra/soul etc. etc.) they had nothing against cloning just that they knew you can’t kill your self then give birth to a clone to live your life for you using your memories and everything.
I hope this helps.
Sir, in a sense if you can imagine the universe providing the primary – dimension where time is 100% homogenous = ’0′ or 1., which is creating New Space second for second since the big bang. You may wish to think on the idea that since the beginnings everything that has happened has been recorded. Thinking on a bit more you may wish to consider that as New Space enjoys constant production at the rate of 300,000kms it may be thought of as an endless spool of magnetic tape ( cutting a plane of it ). Onto this tape the activity of every single atom – or particles -or photon which has ever existed is fully recorded second for second. For example in the time it takes you to read this short idea the local universe has/may have enlarged to a staggering 1 billion cubic miles. This number of course is determined by how fast you read – this number is probably not realistic. But in every second the universe is increasing its manifold size – but of course the sun remains at constant distance to us – and we are totally unaware of its local volumetric increase as it exists as a totally separate dimensional unity. This unity however may well provide the space into which Euclids 3 dimension may be located. Therefore maybe we just to enjoy 4 spatial dimensions and the Primary one is the expansion of the very universe providing new void which is necesary for anything to move in the remaining other 3? Food for thought. So it terms of teleportation if the entire universe consists of a homogenous time then wherever you wish to visit is actually where you are located! Think on the Horizon Problem – how can the temperature at the opposing periphery of the universe be uniform across a huge distance of 40 odd billion light years!! Surely there would exist a small variation in temp where the distance is so vast the possibility of information exchange impossible. ( ‘information’ exchange being the transit of temp from one side to the other to achieve this thermal equillibrium). Ridiculous it would take countless light years for such information to be transmitted across the diameter. Privately it must be because time is homogenous across the huge gap. Think of Newton speed=D/T. If time is zero or 1 then the transit time is identical to the actual distance = spontaneous. I think our basic understanding of the universe if full of flaws hence so many unknowns and paradoxes. In my mind temporal time which can only exist if matter is present all events occur in our experience with a background time reference of zero. Which in thinking more on this even the future. Before it has happened in temporal time. Kind regards ewj.
Professor Strassler,
It is accepted that the strong nuclear force decreases with distance, up to the size of the proton, then remain constant for longer distances. Is there any reason why gravity can’t be thought of the same way, with the strength decreases with distance up to the galactic bulge, then stay constant further out? Is there any research to that end?
Thank you,
Long.
There certainly has been a lot of research as to whether there can be modifications of Newton’s law of gravity at long distance. Ever since the first galactic rotation curves appeared in the literature decades ago, there have been such efforts. Unfortunately, no modification of the force law seems to fit the data very well. For instance, different galaxies have very different shapes and sizes; what determines precisely where the force changes from Newton’s law to something else? The failure to find any modification of gravity that works well is just one of many reasons most physicists and astonomers are convinced that there is dark matter.
Could spacetime be rotating in some way, so that “further out,” the acceleration increases? Perhaps it might be rotating in an undiscovered dimension? [just a novice asking silly questions, hopefully in an appropriate place] Thanks
Professor,
When matter gets converted into energy and vice-versa. is the end result the “same” or something new? Seeing as how it has nothing to go back to, it seems like it turns into something new. Please give me your opinion.
Wow, what i asked before came out to be completely butchered. please ignore this.
Hi Professor
I am a lay person interested in physics. I was wondering if the first law of thermodynamics can really be considered a law. I was viewing a lecture from the Perimeter Institute website by Dr Natalia Toro. She stated that at the sub-atomic level you can borrow energy to make particles as long as they decay right away and the debt is paid really fast. Shouldn’t a law hold in all circumstances? I have also read that our sun does not have the energy required to burn. If not for the uncertainty principle allowing protons that according to the math do not have sufficient energy to get close enough to fuse to actually get close enough? Are these events somehow related?
There are indeed different kinds of laws in physics. There are laws that say: this NEVER happens. There are others that say: the probability that this will happen is so tiny that you’ll NEVER see it happen in the entire history and expanse of the universe. Thermodynamic laws are of the second category, and they do break down as the number of particles in the system you are studying becomes sufficiently small.
Thank you for your reply. The Classic Laws of the Macro world just do not hold in the Quantum micro realm.
Wait!! What you say is true, but it’s not quite the right conclusion in this case.
Statistical/thermodynamic laws are not laws of classical physics which fail at the quantum level; that’s something else.
Statistical laws are laws that govern large numbers of similar objects; they fail when the number is small. This is true EVEN if the objects are macroscopic and effectively classical.
For example, one version of the law of increasing entropy: it tells you that if you take a barrel full of marbles, with all the white ones at the top and the black ones at the bottom, they will mix, but they will never unmix [i.e. the probability is so low that it will never happen if you shake the barrel for the rest of our life]. But it is not true [or more precisely, it requires some modification] if you take a little vial with only six marbles in it. Unmixing will accidentally occur in that case, now and then. That’s all classical (i.e. non-quantum) physics.
“There are laws that say: this NEVER happens…Thermodynamic laws are of the second category…”
Thanks for that, it helps my brain tremendously!
Since you mentioned entropy. In a lecture by Fay Dowker, she said that Jacob Bekenstein said that the entropy of a black hole must be proportional to the surface area of the event horizon. Steven Hawking later found that Black Hole Entropy = Event Horizon Area(in Planck lengths)/4. It got me to thinking that this equation should also hold for any system. Therefore the total entropy of the universe = 4π(radius of the observable universe in Planck units)^2 /4 or π r^2. It also follows that the cosmological constant is really the rate of increase in Universal entropy? Am I way off base here or does this make sense to you?
Professor,
Regarding accellerated cosmic expansion, could one correctly imagine all the stuff of the primordial universe as being scattered by a central explosion, giving more boost to the more centrally located matter, and having less oomph near the perimeter, thus having the the parts with the most impetus travelling faster (hence farther away now) than the less proximal primordial material at the time of the bang?
Also, (if the above idea is out), could the eons old radiation pressure (and other pressures) from all the outgassing of stars, supernovae, QSO’s etc, cause a repulsion in the whole system, of one part for another, resulting in dispersion being greater in the distance than nearby?
In the theory of the Big Bang, there’s no center, and the Big Bang is an expansion of space itself, not an explosion of stuff into space. The image that you have is giving you the wrong impression of what is actually believed to have happened. (Unfortunately this misunderstanding of the Big Bang is not only widespread, it is actually reinforced by most public TV programs on the universe, which show a completely erroneous picture of an explosion. I was appalled to see this even on Steven Hawking’s latest TV series.)
If there *were* a central explosion from some central point, then we would not expect the part of the universe we can see to look almost the same in all directions, and to be largely uniform.
As for radiation pressure from all those photons out there — first, the the effect is far too small even on ordinary matter. And most of the matter of the universe is “dark matter”, a type of particle that neither emits nor absorbs photons, and wouldn’t be affected by radiation pressure anyway. Finally, because the universe is almost perfectly homogeneous (at least the part that we can see), without a center, there is equal pressure from all sides, and no net force outwards. Those photons do affect gas and dust inside of galaxies, and around stars, so these effects are studied by astrophysicists and astronomers in detail.
Some early renderings of the CMB sky show a disk with a red half, swirling into a blue half. The explanation was that this was before certain corrections were applied. Doesn’t this indicate an off-centered-ness to the energy that was recorded, suggesting motion in some direction?
Yes — the universe is engaged in an overall expansion, and is largely uniform on average, but any individual galaxy is moving relative to that overall expanding uniformity, and ours is no exception. This creates a Doppler effect in the cosmic microwave background (CMB), which is uniform with respect to the overall expanding universe. The existence of this effect was no surprise and was fully expected.
Once you remove that one effect, you can see that the universe at large scales was extraordinarily uniform in the distant past, at the time when the cosmic microwave background became uncorrelated with what the matter around it was doing.
You can think of that as a little like the motion of a boat through a uniform sea. To realize that the sea is uniform, you have to first correct for the motion of the boat through the water.
I wonder how inflation affects this issue – since the universe leaves the inflationary era at different points at different times, does that not provide some kind of centre to our universe?
Well, the fact that inflation may make the shape of the universe very complicated may indeed mean that there are edges between different “patches” where the universe is very different from what it is in the middle of a region. But unless you are in a rather small inflationary patch, or near an edge of a patch, there won’t be any simple experiment you can do to figure out where the center of your patch is. In principle you could try to define it but in practise you won’t be able easily to detect it.
At large scales, it’s safe to ignore quantum mechanics and focus only on general relativity; at small scales, you can ignore gravity and concentrate only on the quantum aspect of nature. So it seems you never need both quantum mechanics and general relativity at the same time in order to descrive a physical phenomenon.
Knowing this, do we currently have some need for a theory of quantum gravity? Obviously, understanding the fundamental rules of the universe is a noble goal by itself, but what I mean is if there’s a known and observed phenomenon/physical object that is currently waiting quantum gravity to be properly understood. I’m guessing some sort of weird star or black hole?
In a sense, if we had an immediate need, we’d also have an experimental setting in which to study it. So the answer as to whether the need is clear is perhaps no.
On the other hand, it’s good to study it in case we run into it in an unexpected place. If extra dimensional effects were detectable at the LHC (so far indications are that they are not) then we might in fact run into gravity (in the form of quantum black holes and gravitons etc.) at accessible energies.
Also, the relationship between quantum field theory and string theory that was discovered by Maldacena and friends makes us want to understand quantum gravity as a way to understand quantum field theory better — and quantum field theory really is part of the real world. We are more likely at the LHC to run into a quantum field theory process that can be usefully understood using gravity (classical or quantum) than to actually run into quantum gravity directly.
But when Einstein developed general relativity it wasn’t clear there was a need either. Only after the theory was developed did it occur to people to look at the bending of light by the sun — a new type of experimental question. Today we use this “gravitational lensing” to study the universe.
So you can see the argument that you should develop the theory in hopes that an experimental test will become clear once you understand it. And at that point this might lead you in new experimental or observational directions where you really would have a need for quantum gravity on a regular basis.
And, of course, as any good newspaper would say, quantum gravity may help us understand why there’s more matter than antimatter in the universe (haha, just kidding).
Anyway, thanks for the answer!
Update on the mass of neutrinos:
http://www.tgdaily.com/general-sciences-features/63827-subterranean-search-for-neutrino-properties-yields-first-results
The article claimed that the experiment narrows down the mass of the neutrino “to less than 140- to 380- thousandths of an electronvolt”.
Dr. Organtini has a paper explaining the Higgs mechanism:
http://arxiv.org/abs/1207.2146
Between equation 9 and 10, there is a new term, (phi^4), is that because we are assuming that the self-interaction of the Higgs field is negative?
Long.
The approach he takes is interesting. The one I am preparing is very different; they will be complementary.
I think he just adds this term because he can… but I should read this carefully to see if he has a more motivated line of argument.
Hi Matt,
I have a simple question (these are the most difficult to answer sometimes). Maybe the answer has already been given.
It s about the Zero Point Energy of the EM field.
As a consequence of the Heisenberg Uncertainty Relation (or non-commutativity of operators), there remains some energy once you have removed all the photons (one half h omega). This is the ZPE. You can show that you still have an electric field and a magnetic field. Their mean value is zero, but there is a non-zero variance (thus some energy). So you have E and H, but NO photons. First question : can E and H be considered as noise ? I guess yes (zero mean value and non-zero variance). That’s probably what people refer to when they say “fluctuations”. Does fluctuation mean noise ? Is it equivalent ?
Second question : this happens with NO photons around. My understanding is that ZPE is a stationary field, not propagating. There are really NO photons whatsoever. Neither real nor virtual. Right or wrong ?
Usually people think about these fluctuations as virtual photons popping in and out. But this means there are photons (even if only virtual). Isn’t that contradictory with the fact that the number of photons is zero ?
Thank you.
Christian
if we happen to remove our hand just when flow of electrons is approaching the other end of wire what will happen to the energy spent by the electrons and where will it go?
Sorry, your question needs to be more precise. What exactly are you talking about?
the flow of electrons constitutes current, now we know that the speed of the electrons can be considered as about 90-97% of light and if suppose a wire is plugged in the socket of 220V and because of the difference in potential as on end of the wire is free, and naturally the flow of electrons will be there. initially i placed a conductor at the other end of the wire and as soon as the potential was developed, the flow of electrons was there, i suddenly remove the conductor as fast as the flow of electrons by some means( although not possible) what will happen to the energy spent by the electrons as conservation of energy is true?
I am afraid that right from the beginning you are profoundly confused about how current works and what electrons are doing inside a wire both in the absence of and in the presence of current. Your statement about the speed of the electrons is both incorrect and confused. First, you have the speed wrong. But second, and more important, it isn’t the speed of the electrons that determines how quickly the current builds up. That’s determined by the speed with which the electric field builds up along the wire. Moreover, just like atoms in a light breeze, the electrons’ motion is mostly random with a slow overall drift, so their speed isn’t what determines how fast they flow in the wire. The electrons move fast, but most of that motion goes nowhere; the slow drift that leads to a current is very slow. http://resources.schoolscience.co.uk/cda/16plus/copelech2pg3.html And energy conservation inside a wire is extremely complicated, because the electrons are regularly banging into things inside the wire and losing energy to the lattice of atoms that make up the wire; that’s why the wire heats up (through electrical “resistance”) when you pass a current through it, and why the current doesn’t keep growing even though an electric field should be accelerating the electrons to higher and higher speeds. You can’t keep track of the energy of the electrons unless you keep track of all the heat that’s being lost to the lattice of atoms.
In superconductors things are different, because there is no resistance; but you don’t use those in ordinary wires.
I have a fundamental question:
When I think of elementary particles as the electrons and quarks, may I think (imagine) of them as “euclidean points” in space, as something without structure, or, as I understand from quantum field theory, as ripples in their corresponding fields, i.e. as something with 3 dimensions (the dimensions of the field)? Maybe as an infinitely peaked ripple in the field (~deltas)? If this is the case, is it correct to imagine an electron “flat” field that becomes extremely peaked when an electron appears?
Nice question – I also await Matt response….>
I have thought that maybe one cannot imagine it one way OR another due to particle-wave duality…
I also forgot to thank and congrat proffesor Matt Strassler for the great blog
I hv posted the following under “New ? Start here”.
I later noted there are ‘Enlightend’ souls here (Technical Zone) who may shine my path too.
Pls comment if you find my question worth your attention.
I am looking for an answer in terms of Particle Physics, if possible.
REGARDS
UT
QUOTE:
UT | November 23, 2012 at 3:00 PM | Reply
Respected Prof,
It is indeed privilege to post a question to you directly. If fortunate enough, (me) expect to receive a considered reply.
Of late a simple question is bothering me a lot !!
Given :
When two bodies (A & B) collide Kinetic Energy is exchanged. Total Momentum is conserved.
Question ?
1) How does the bodies retain the Kinetic Energy.
( we do know how the Heat is retained)
Observation: :
More Kinetic Energy (equals more velocity). Say A was faster before pushing B (from behind, like cars in the same lane)
After collision, change in velocities of both bodies takes place. ‘A’ slows down & B goes on faster after a push.
MY REMARKS
The change that has enabled the body B to negotiate the space in front more efficiently (faster).
Question ?
What has changed ?
Is this change something to do with the space property ?
Is this change has to do with the body and space both ?
or this change has changed something inside A & B.
Interesting Scenario !!
Say we fire a bullet. The bullet has two motions.
a) forward (x axis)
b) spiraling around its forward motion (x – axis)
c) the bullet strikes a thin wire. It acquires another motion. Spinning (in addition to above (y-z-axis) as well.
To make it simple – the question is ?
How does the body retains the ‘Memory’ of motion (on all 3-axes).
AND
the question is :
How does this memory is transferred to new body on collision ( in what form, from where to where (mass to mass, of course)
From where it is released.Where it is received. And where it is then retained ?
With SINCERE REGARDS – UT
Dear Matt, thanks for a great website!
I was reading an article on the “5 sigma rule” of experimental physics and although the article was not very deep, it got me thinking and I have a few questions regarding inference drawn from physics experiments:
How do scientists calculate the uncertainty in the results concerning a scientific theory? I.e. how do we know “how many sigmas we are at”?
I would guess that most (all?) scientific data would be far from normally distributed, so do the scientists invoke the central limit theorem? If yes, I see a couple of potential problems:
(1) We naturally only have a finite sample, hence the normal distribution assumption is only approximately correct. What happens if the convergence to the normal distribution happens extremely slowly for some reason? Is there a way to test for this in a given scientific experiment (without imposing additional assumptions on the data generating process)?
(2) In a similar vein, and taking the Higgs as an example, I imagine that both ATLAS and CMS collect huge amounts of data, thus strengthening our belief in the CLT-approximation. But if the Higgs in only rarely detected, we actually have significantly less data than one would imagine from the number of collisions being recorded. Is stuff like this taken into account when calculating the “5 sigma”? (I would guess yes, but I dont know the procedure)
(3) What if the assumptions underlying the particular central limit theorem being used are violated? How do we check for this? And can we be certain in any conclusion regarding the validity of the assumptions?
Are the above questions trivial for a physicist or could they pose problems? Are scientists actually asking these questions when doing experiments and inferring from them?
Hi! I am a retired physics prof. here. Only a few days back I became aware of your excellent blog .From now on I will read your blog carefully!
I have two questions. (1) I understand that baryon masses cannot come from Higgs. But I have a feeling that quark model will not work with zero or very small mass quarks anyway. Will the lattice gauge calculation work with zero or very small quark masses? So Higgs may be necessary for baryons also. What do you think?
Also can you give me a reference which calculates with what energy quarks or gluons collide for a given cm energy of the two protons. I suspect it is quite involved and depends on the specific details of each collision in addition to the cm energy. Perhaps for each event one has to reconstruct. Is this right? Thanks.
Kashyap Vasavada
I am withdrawing the first question!!! I got the answer in Wilczek’s article on origin of mass. I will appreciate it if you answer the second question.