tag:blogger.com,1999:blog-34480619.comments2024-03-11T13:47:03.621-05:00Physics and PhysicistsZapperZhttp://www.blogger.com/profile/15861398273820851809noreply@blogger.comBlogger2781125tag:blogger.com,1999:blog-34480619.post-78543088003767365322024-02-02T12:26:53.864-06:002024-02-02T12:26:53.864-06:00For me its oppenheimer
He is a revolutionary phys...For me its oppenheimer <br />He is a revolutionary physicist and a cutie for me <br />Ad10935https://www.blogger.com/profile/03974905173496612504noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-14682942133091016462023-03-11T10:36:51.562-06:002023-03-11T10:36:51.562-06:00ZapperZ, In reverse bias P-N junction diode, do th...ZapperZ, In reverse bias P-N junction diode, do the thermally generated electrons in the P-region cross the depletion region due to the attractive force of the battery's positive terminal or due to quantum tunnelling?motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-31752090642168330902023-02-28T10:24:25.622-06:002023-02-28T10:24:25.622-06:00You won't beleive, but your article is now a s...You won't beleive, but your article is now a search engine spam, which is poping up on that question on Google. So, imagine, you are googling this question and getting a lecture about you don't know how to use Google. Funny.Dimshttps://www.blogger.com/profile/01849248904594906457noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-33278695437546785382023-02-16T10:35:54.636-06:002023-02-16T10:35:54.636-06:00Hello, ZapperZ. I am back again with some question...Hello, ZapperZ. I am back again with some questions and i hope you don't mind to share some thoughts more. I read somewhere on Physicsforums your post, where you hold that (in physics) a claim must be backed by empirical evidence, or else it isn't physics. I could not agree more with your claim and with that sort of strong empiricism. However, i keep on receiving counter-arguments again and again. It is all about the astronomically small probabilities which arise in quantum mechanics due to the mathematical framework. Some people claim these probabilities are correct (even if we can't confirm them in remaining life-time of the Universe) just because the math model is very successful in the range of the experimentally confirmable range... so it must work in the infinitesimal probabilities. But i just hate those "effectively" zero probabilities lurking all around in QM. Because effectively zero does not mean zero... It means "possible"<br />motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-90999108610770075952023-01-16T17:12:50.666-06:002023-01-16T17:12:50.666-06:00Danielle,
But in what way is it more useful for t...Danielle,<br /><br />But in what way is it more useful for those students? What is the difference? Have you done any kind of assessment to verify this?<br /><br />Z.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-52535425944508534432023-01-16T09:33:26.458-06:002023-01-16T09:33:26.458-06:00I've been thinking a lot about this over the y...I've been thinking a lot about this over the years, but mostly from a "what's real and what's accounting" perspective. What I mean is that Newton's laws can be thought of as momentum accounting:<br />3: things swap momentum<br />2: the rate of momentum swap is interesting to keep track of<br />1: if you don't swap it's boring<br /><br />Then energy comes from a much more sophisticated accounting trick, but I'm trying to decide if I can say that, while momentum exists (it's what's constantly being swapped), energy is a human construct that dramatically improves our ability to make predictions. No question it's a tough sell, and it gets really weird in quantum mechanics. Also I'm not sure it helps students who we're just trying to help develop some useful models.Andy Rundquisthttps://www.blogger.com/profile/04900696452285397726noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-53002549397137150002023-01-16T08:29:45.370-06:002023-01-16T08:29:45.370-06:00That depends on the math background of your studen...That depends on the math background of your students. I found that ordering useful for the students who struggle with math. Daniellehttps://www.blogger.com/profile/16467789488500908232noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-10735759257207097092023-01-16T07:59:19.653-06:002023-01-16T07:59:19.653-06:00Is this a major issue, i.e. keeping the students s...Is this a major issue, i.e. keeping the students stuck with "vectors" first before switching to using scalar quantities? After all, they have to do this again when they deal with circular motion. This switching back and forth between vectors and scalars is not something I find problematic.<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-22505179766488670232023-01-16T07:57:20.347-06:002023-01-16T07:57:20.347-06:00Why should it be explained without using tunneling...Why should it be explained without using tunneling concept when it is a tunneling phenomenon?<br /><br />Z.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-34052444582267102282023-01-15T07:39:42.491-06:002023-01-15T07:39:42.491-06:00ZapperZ, quantum tunnelling (of electrons) is ofte...ZapperZ, quantum tunnelling (of electrons) is often given as an explanation for the leakage current in the p-n junction. Could you, please, help me with a physical explanation for the leakage current without the tunnelling concept? How can it be explained without QM (if that is possible)? Thank you very much!!motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-90129754833306672502023-01-14T11:34:59.610-06:002023-01-14T11:34:59.610-06:00The advantage to teaching momentum before energy i...The advantage to teaching momentum before energy is the continuity for students in working with vector quantities. If you teach momentum after energy, students will tend to treat it as a scalar. If you teach it before energy, they tend to know it should be a vector - although they still have plenty of struggles with the mathematics in my experience. Daniellehttps://www.blogger.com/profile/16467789488500908232noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-1557087223885496692023-01-14T08:56:55.351-06:002023-01-14T08:56:55.351-06:00Doug,
I can see your point, but I just think it i...Doug,<br /><br />I can see your point, but I just think it is a bit tedious to have to go back to discussing momentum again after the introduction of energy concepts just to explain the idea of inelastic collisions. I much prefer to start with energy first, then introduce momentum, and tackle both elastic and inelastic collisions in one single shot. It just feels less fragmented that way.<br /><br />Besides, I can immediately start with the experiment on conservation of momentum to include both elastic and inelastic collisions.<br /><br />BTW, I was going to make a post on this, but over the holidays, out of the blue, I was curious on what happened to Hendrik Schon and did a google search on him. I didn't find any new updates, but what I did find was your amazing account of the whole event. Somehow, I did not know that you were at Bell Labs when this all transpired. I only heard 2nd and 3rd hand accounts of the rumblings that no one could duplicate his results (I was at Brookhaven back then), so having your first-hand account made for a very riveting reading (it also ruined my attempt to sleep that night! :)).<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-16836037394643392332023-01-09T11:24:53.642-06:002023-01-09T11:24:53.642-06:00At the beginning level, I'm not sure that the ...At the beginning level, I'm not sure that the order makes a huge difference, but I think it makes some sense to start with momentum and then do energy. When considering test objects in intro mechanics, momentum is always conserved, because there's nowhere for it to "hide". Even in inelastic collisions, momentum is conserved. Energy is also always conserved, but friction and inelastic collisions take energy out of macroscopic motions and "hide" it in microscopic jiggling that we can't readily track. That's a bit more of a subtle point, hence maybe having that come second. Douglas Natelsonhttps://www.blogger.com/profile/13340091255404229559noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-6239278637139917172023-01-01T13:16:40.978-06:002023-01-01T13:16:40.978-06:00ZapperZ, it seems that not only atom can tunnel th...ZapperZ, it seems that not only atom can tunnel through the same barrier, but even a whole trifluoromethyl group. I was brutally tackled with the following article: https://www.chemistryworld.com/news/huge-molecular-fragment-quantum-tunnels-in-everyday-lab-reaction/3008209.articlemotaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-91431994141098899182022-12-24T17:27:54.114-06:002022-12-24T17:27:54.114-06:00Each particle has a tunneling probability, but the...Each particle has a tunneling probability, but their tunneling probability is DIFFERENT from one another.<br /><br />A potential barrier for an electron looks like a potential WELL for a proton! Same barrier, different probability of tunneling for each of the particle. So how does a hydrogen atom tunnel through the SAME barrier with the SAME probability for each of its constituent?<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-87293178327173680142022-12-17T23:27:49.085-06:002022-12-17T23:27:49.085-06:00Zapperz, the debate about quantum tunnelling of &q...Zapperz, the debate about quantum tunnelling of "macroscopic" objects (in which I am involved) is getting really heated. There's a guy against me who gave the following argumentation: "A macroscopic object doesn't have to be in coherent state in order to quantum tunnel. The probability for such event is ASTRONOMICALLY small. However, each particle of the object is subject to a tunneling probability and you can certainly calculate the probability of all of them doing it at once. In similar vein, we have NEVER ever observed getting a "6" 10^43 times in a row when rolling a dice, but it doesn't mean it is physically impossible and we can calculate the probability for such event."... So, it seems to me that I am loosing the debate.: it seems that quantum tunneling of "macroscopic" objects IS NOT forbidden by the fundamental laws but just the probability is fantastically small. Please, share your thoughts about the subject one more time.. i really need some arguments on my side. I can't get along with the idea that quantum tunneling of macroscopic objects is possible (although improbable)...motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-59671152552093723802022-12-14T09:38:18.046-06:002022-12-14T09:38:18.046-06:00The tunneling probability depends on mass. In fact...The tunneling probability depends on mass. In fact, it decreases with increasing mass. A macroscopic object is definitely more massive than an electron.<br /><br />Another factor to consider. A potential barrier for an electron looks like a potential well for a proton, and vice versa. Already the tunneling probability for, say, a neutral atom is not going to be the same for each component that makes up the atom.<br /><br />Z.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-59854011371663742042022-12-12T10:26:42.460-06:002022-12-12T10:26:42.460-06:00ZapperZ, theoretically, does a "macroscopic&q...ZapperZ, theoretically, does a "macroscopic" object (prepared in coherent state) have the same probability for quantum tunnelling (through a given potential barrier) as an electron?motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-12950712896582060082022-12-08T07:25:58.132-06:002022-12-08T07:25:58.132-06:00Look up "field emission". This is a comm...Look up "field emission". This is a common phenomenon due to tunneling.<br /><br />Z.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-11377128016462645472022-12-05T22:16:21.683-06:002022-12-05T22:16:21.683-06:00However, let's consider a solid. A piece of me...However, let's consider a solid. A piece of metal or a piece of wood - it doesn't really matter, just a regular solid at room temperature. Some people are telling me that there's non-zero probbaility (very small) for a subatomic particle in the solid to completely "escape" from the solid due to quantum tunnelling. Can really the particle escape the binding forces of the solid? In my humble opinion, this is completely impossible because tunnelling is only between states with the same energy. The final state of the particle outside of the solid would have very high energy and that is violation of the conservation of energy. Or maybe my argumentation is wrong? Could you please elaborate a little but your opinion about the given scenario...motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-82689722632247107062022-11-30T06:23:40.352-06:002022-11-30T06:23:40.352-06:00I don't know of any such papers or physicists....I don't know of any such papers or physicists.<br /><br />On the other hand, you might want to ask the same thing of "them", i.e. if the experimental evidence are in the "wings", then there should have already be theoretical development to show that such a thing can be reasonably measured (notice I wrote "reasonably"). Ask them for such a publication.<br /><br />Other than that, I consider this to be a waste of time.<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-20657476050873269472022-11-29T23:04:55.648-06:002022-11-29T23:04:55.648-06:00The experimental observations actually are in acco...The experimental observations actually are in accordance their claim: in the "wings", the probability is so astonishingly small that it will never happen in the age of the Universe. Is their claim effectively untestable? For sure! Is their claim correct or not? We don't know! Personally, I don't like tge concept of "effectively zero". I don't find it rigourously scientific: at WHAT point we consider a certain probability as "effectively zero"? Obviously, it is not well defined concept. On the other hand, I strongly appreciate your insisting on empirical confirmation. Quantum tunneling of subatomic particles happens on a daily basis in the cores of the stars (of course, under very extreme conditions, high temperatures). It happens also in the SSD devices (under not so extreme conditions). Also, you are not claiming that tunnelling of macroscopic objects is forbidden by quantum mechanics.. at least, it seems to me so, as far as I can understand. By the way, could you please point out for me physicists (even if not mainstream) who actually claim that quantum tunneling if macroscopic objects is forbidden (completely zero, impossible)? I will be very interested to read such papers, if they exist in the scientific world....motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-22779203187457430862022-11-29T20:46:27.854-06:002022-11-29T20:46:27.854-06:00But what about experimental evidence?
It seems th...But what about experimental evidence?<br /><br />It seems that the people you are in contact with don't seem to think that validating their ideas with experimental observation is necessary. Have you ever asked this to them? Because if this is their take on how we do science, then the conversation should stop right there! They are not doing science, but practicing some form of a religion.<br /><br />I did my PhD in tunneling spectroscopy in high-Tc superconductors. I do mainly single-electron tunneling. In a few cases, I did what is called Josephson tunneling, in which two electrons that make up a Cooper pair tunneling across the barrier.<br /><br />However, here's the caveat - the two electrons that tunneled across are in a COHERENT STATE with one another!<br /><br />This is related to what I said earlier about macroscopic object, i.e. the inability for the the entire object to be in a single, coherent state. It is not the size, but rather the ability to get the entire object to be coherent. I don't see how this can be done. It is already difficult enough to do this with two electrons, i.e. they have to be in a superconducting state before this would even occur!<br /><br />I wish people who would claim such a thing would get out of their houses and go do a few experiments already.<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-87333181485965373782022-11-29T11:15:35.223-06:002022-11-29T11:15:35.223-06:00I really appreciate your further explanations and ...I really appreciate your further explanations and details. As I said, I am completely layman in the topic, so I cannot give relevant scientific argumentation. However, I believe that atoms, molecules and macroscopic objects are fundamentally incapable of tunnelling. So, it is fundamentally meaningless to even calculate and mathematically speculate about the non-zero probability. We have never observed an atom to quantum tunnel. Only subatomic particles: electrons and protons. Yet, quantum fundamentalists claim that I am wrong because I cannot prove that macroscopic objects have emergent property which COMPLETELY prevents them from tunnelling. So, they are insisting again and again on the mathematically derived non-zero probability. However, I think that they cannot prove their belief, just like I cannot prove my opinion. It's just that their astronomically small probability is untrstable. So, it is Belief vs Belief. A matter of opinion. Do you agree?motaro2022https://www.blogger.com/profile/09621039355663215418noreply@blogger.comtag:blogger.com,1999:blog-34480619.post-31172437530937418642022-11-29T08:38:13.492-06:002022-11-29T08:38:13.492-06:00Let me ask you this. Take a vase that has been sma...Let me ask you this. Take a vase that has been smashed into thousand of pieces. Now throw those pieces onto the floor. What are the odds that it will fall just right that it reassemble itself back into the original vase?<br /><br />No one in his/her right mind would consider this as a reasonable possibility. In fact, most rational people will say that this does not happen, and history has shown us that it HASN'T been shown to have happened. But yet, statistically, it isn't zero! But does that mean that it can and will happen?<br /><br />What is the gravitational force from Alpha Centauri? For every practical measurement that we make here on Earth, the gravitational force from Alpha Centauri has NEVER been considered, nor is it a fact in anything that we do. Yet, it is still non-zero! But is it rational to keep harping that just because physics says that it is non-zero that it must be considered in every single calculations that we make?<br /><br />I will once again reiterate that just because someone can come up with a theoretical description, it doesn't make it correct. Without experimental evidence, it is simply a belief. And the one who is proposing it is the person responsible for providing the evidence, not the other way around, i.e. it is not the responsibility of other people to prove that idea wrong.<br /><br />Zz.ZapperZhttps://www.blogger.com/profile/15861398273820851809noreply@blogger.com