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.
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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.
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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.
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.
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.
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.
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.
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.
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!