A night with the stars (Brian Cox on telly)

Ken G

What's more, even technically we should probably avoid language like something "happening simultaneously" on the Moon. Relativistic quantum mechanics must respect the limit of causal effects to propagate at less than c, so it is only what we regard as happening on the Moon that is altered simultaneously to the change in what we regard as happening in Manchester. What is "actually" happening on the Moon is a matter for people on the Moon to decide authoritatively, given the local limitations on the act of doing observations. I guess you can call me a positivist!

ThomasT

Apparently, according to Brian Cox, your mistake might not (in some sense) really be a mistake. And anyway Brian Walsh is a lot closer to any of us than the moon (not that that matters). As atyy and others have pointed out, what Brian Cox said can be considered technically correct. But as Ken G and others have pointed out, it's important how formal QM is translated into ordinary language, because its precise relationship to nature is very much a matter of interpretation.

I'm still of the opinion that Brian Cox's popular presentations are meant to entertain, and not necessarily to inform or clarify -- and that it remains for each of us to learn enough of the technical theory to decide for ourselves when and if the mathematical formalism might be translated literally into ordinary language statements about nature.

So, there you have it. Brian Cox's (and anybody else's) popularizations can be taken to be correct statements about reality or nature ... or not, depending on how one chooses to interpret the mathematical formalism.

SecularSanity

Seems to be some confusion here about far apart and isolated atoms. Personally, I think it was intentional, to push a new book.

“When they are far apart and isolated, the atoms have identical energy levels. However, as the spacing between the two atoms becomes smaller, the electron wave functions begin to overlap. Antibonding orbital are repulsive and act to destabilize the molecule as a whole..”

http://en.wikipedia.org/wiki/Antibonding

Lec 14 | MIT 5.111 Principles of Chemical Science

Double Twit Experiment – What Brian Cox Gets Wrong

Ken G

In my opinion, that last link is unpleasant and unjustified. If framed as a list of constructive criticisms for Cox to consider in his next presentation, it would only have been presumptuous. As it is, it is a vitriolic diatribe with no apparent reason for existing other than to express a very large chip that the author seems to carry for Dr. Cox. It makes one wonder if Brian kicked sand in his face when they were kids! I only found it interesting for the nice clips it gives of other lecturers, but it is no kind of critique of Dr. Cox that people like Feynman give great lectures. They can all have their own style, and the audience can be allowed to decide their preferences.

James_Sheils

Hello,

I am the author of the review "Double Twit Experiment – What Brian Cox Gets Wrong", as linked by others.

I came across this thread after Cox's BBC show and linked to it in the blog article. I was surprised to notice a few days later that someone on the forum had linked back to what I had written, and that many people are reading it via this thread.

For Ken G and others who may find my comments 'unjustified', allow me to elaborate a little.

I am a maths and physics graduate who has taught physics in secondary schools in the UK for around 6 years. During this time, I've thought quite carefully about which parts of scientific inquiry are worth teaching - which ideas and skills are valuable.

For classroom teaching, there is inevitably a conflict of interested when we consider how long a student might stay in science education. Some, who will go onto further study, need to be equipped with particular skills and informed of specific ideas. Those who will go on to do other things after high-school will likely find little benefit from these skills. I'm talking about learning how to use a micro-metre, or learning which of Newton Laws is which.

However, there is much of scientific inquiry that is valuable to everyone, regardless of specialisms. Most important of all, any citizen will benefit from understanding the process of scientific thinking. The role of evidence in falsification, what constitutes a scientific theory, how logic is utilized to determine consequences of a theory, the imaginative guesses that bring about new theories. All of this equips a person with thinking skills and understanding they can apply to enrich their lives, and their understanding of the latest research.

Values to extract from this include: anti-authoritarianism, fallibilism, logical analysis, philosophical reflection and courageous imaginations.

Let's suppose you think this is too abstract or challenging. Which parts of physical theory might be valuable knowledge to everyone? Some basic knowledge of Newtonian mechanics, descriptive optics, electrical circuits would be a good start. Sure, they approximations for theories we now know to be closer to the truth, but if taught well they will not impede possible future study.

So what to do with a 1 hour presentation? Now, i'm sure there will be much noise about how producers won't agree to programs that present these 'old' ideas. But Cox seems to command a lot of respect - they have already agreed to let him give a one hour lecture with a blackboard.

It is disappointing that he has decided to present something so esoteric, yet mostly rely on intellectual intimidation and argument from authority to establish the results. Sure, he tried some underrehearsed explanations and demonstration, but the material was far too broad for even the greatest of educators to do a good job.

So what is the result? We have people who think they are interested in science, credulously parroting the latest scientific ideas to each other at the dinner table.

Most dangerous of all, it encourages already arrogant students to presume they have understood an idea, when they have merely remembered some impressive words. I have met many students who have tried to explain black holes to me, or something about string theory. I always fell a sympathy that these curious minds have been duped by yet another shallow presentation of scientific inquiry.

Or, there are the adults I meet who tell me they are 'really interested in science' and then ask me about m-theory, or black-holes.

"Why do some object float in water?" I ask them. Most of them have nothing to say about this. Now I ask you, if a person cannot connect the perceptions of their experience with scientific patterns, what is the possible value in describing the theoretical intricacies of the latest research?

In short, I think presentations like Cox's contributes to a social game that people play, to impress and stupefy. But not to understand.

unusualname

unfortunately the relevant pages 274,275 are not available in my google books preview. But if you have a (free) amazon account you can just search for the word 'moon' in the 'Look Inside!' view


http://www.amazon.co.uk/reader/03064...TF8&query=moon

(The relevant section starts on p 273 called 'When Can We Ignore Symmetrization and AntiSymmetrization?')

The point is that the the type of effect Cox tried to popularize, is in fact completely negligible in practice, even if quantum mechanics, as we currently formulate it, is exactly theoretically correct. But he did link to lecture notes where this point was made explicit to ~50 decimal places in his first post on the thread (several weeks ago)

SecularSanity

Bravo, well said. I enjoyed your review. The internet is plagued with so-called wisdom. For those of us who are interested in science, but wish to avoid the pseudo-junk altogether, can you tell us how to find trusted sources?

Wikipedia can be a good starting point, right? From there you can check all the references to see if the authors are from a university, research facility, or published in a reputable journal. Peer reviewed is more reliable and clearly, arXiv is not peer reviewed. It can contain some dubious e-prints but most of the authors care about what they write. If the website ends with .gov or .edu it’s probably a good source, right? Can you think of anything thing else to add?

List of Scientific Journals

How the Scientific Peer Review Process works

Misconceptions about science

What is Science?

P.S. If you’re such a stickler, here’s a suggestion for your next write up.

Why does a photon slow down in a medium?

There are tons of explanations out there. Here is ZapperZ’s explanation from in here and another from yahoo. Is either of these explanations accurate? If not, then perhaps you could provide a better one on your blog.

http://www.physicsforums.com/showpos...93&postcount=4

http://answers.yahoo.com/question/in...8084206AALZBC5

atyy

Let me add that although the topic was first introduced in scenario where the effect is so small as to be practically negligible - the antisymmetry of fermionic wavefunctions that Cox talks about is very important. Matter would not be stable without it, nor neutron stars exist.

http://rmp.aps.org/abstract/RMP/v48/i4/p553_1
http://www.astro.umd.edu/~miller/tea.../lecture17.pdf

James_Sheils

Thanks for your kind words.

I agree that Wikipedia is a good starting point. Contrary to popular opinion, Wikipedia has a very high fidelity, in physics at least. I hear from specialists in other fields, such as art history, that the pages do not generate enough interest from editors to be reliable. However, in physics there seems to be a good supply of specialist contributors. The only disadvantage I have found is that for a non-specialist, the pages can be difficult to understand. But Wikipedia is a reference source, not an educational program.

I agree with what you say about the other sources, but would always read them with a skeptical mind. As I mentioned in the article, I think the best source for basic physics comes from Walter Lewin's MIT course.

As for the photon question, that's a pretty difficult one to answer, and I can't claim to fully comprehend all the details of modern theory!

I think the explanation you linked was right to avoid single atom explanations, but did not address the faulty assumptions in the question.

As the Double Slit Experiment aims to elucidate, we are not able to measure what happens between a photons emission and its arrival without changing the conditions sufficiently to alter the experiment. And the double slit experiment summarized the very counter-intuitive results concerning detection of photons. They arrive as particles, but do not seem to behave as particles on their journeys.

Encapsulated in the Copenhagen Interpretation of QM is a policy of not trying to speculate about 'where the photon goes' from source to detector.

We might have some mathematical equipment to calculate the probabilities of where the photon might end up, but we don't (or can't) know which path it took. Indeed, QED calculations assumed you need to consider every permissible path to determine the probabilities. So we can't appeal to the mathematical calculations for a satisfactory answer.

Thus, to as 'why' and expect a deterministic 'then the photon does this...' type of narrative asks too much of quantum mechanics.

But, the question could be answered by describing why the extra calculations for the material seems to delay the probability of a photon's arrival, compared with it traveling through empty space. I don't have sufficient quantum mechanical answer for this!

Ken G

So have many of us. Do you recognize that this practice generates in you a number of opinions, that can be expressed without automatically assuming yours is the complete and final truth of the matter? The most important element of the art of advancing an opinion is the high regard for decorum, civility, and the right to respectfully disagree. Polemic diatribes are both easy, and tempting, but often limit their impact to a relatively small set of die-hard afficionados.Absolutely, essentially any science educator would agree with that. The issue is, does each person who gets on the internet for a half hour or hour presentation need to feel responsible for all that, or is this more logically the mission of the science educator in the classroom setting?
I agree completely, and indeed from your comments on Dr. Cox I formed the opinion that you are most likely both very capable, and very dedicated, in your science education mission. You probably teach very well, and linked to others who do also. But none of those facts actually justify that vitriolic critique. Not everyone needs to adopt the same mission that you would, in order to be considered of value to science in some objective or demonstrable way. In short, they do not necessarily need to submit to your judgement of their performance. The question is, what audience is your criticism intended for? If you want Brian Cox to pay heed, the tone would rule that out-- I doubt he would read past the first few paragraphs. If your goal is to get people who like to listen to him to boycott him and listen to others that meet with your approval, I doubt you'll have much success-- those inclined to agree with you have probably already formed a similar opinion and don't seek out Dr. Cox's presentations, and those who like them will most likely not be dissuaded, because they simply won't agree with you. If you want to reach that crowd, I think you'd do better with your own presentation-- enlighten and entertain in your own way, achieving those goals that you value, and reach that clientele in that manner. That would accomplish the same goal, but more effectively than a largely unfocused critique-- it's easier to teach than to unteach.
And this is the fundamental flaw in your position. Here you suggest that your goal is to convince Brian Cox to use his hour differently. Do you really think the way you presented your position is likely to accomplish that? Your comments are not even directed to Dr. Cox, they are directed to people who would listen to him. So your goal is clearly not to get Dr. Cox to use his hour more effectively, which would be a constructive goal (though presumptuous), it is to get those who would listen to his hour to avoid it or join in the Brian-bashing. How is that going to teach people Newton's laws?

What's more, you are overlooking the fact that there may be a reason that Dr. Cox is getting this hour (and a blackboard!), and neither you nor I are-- he has proven the ability to entertain and energize his viewers. Personally I think I could put together something that would be entertaining and enlightening also, which you might find less occasion to criticize if we share similar educational values, but I'm not going to get the opportunity to reach such a huge audience. I'm just not, the issue is moot. So I can see value in a certain trade-off there-- yes, perhaps there is an overemphasis on what is titillating rather than what is good basic science, but it's not such a bad exchange to get these ideas out there to people, to help them see that scientists are not just in ivory towers discovering arcane looking equations that somehow helps us build better iPads. Instead, we are getting glimpses deep into the workings of our reality, and getting quite amazed in the process, and we are inclined to want to share some of that experience with a larger audience.
OK, so maybe not everything he did worked as well as it could have, and maybe he can learn some lessons for next time. He probably knows that, or if he doesn't, a simple constructive comment might be all that would be needed. What's the purpose behind all the bashing? That's what I really think you should look at more closely, what is really pushing your buttons here? For example, why do you think that his primary motivation is to make himself feel smart? I think it's pretty clear what his primary motivation is, it is to share with others some of the amazing glimpses he feels he has gotten into our reality. Of course it's also fun to feel smart, and of course it's also a rush to be able to entertain, I hardly think we can criticize the comedian for liking to hear a house full of laughter!
But this is unavoidable. Do you really think this never happens to your students? At least the people in question are interested in something that connects with science-- the alternative may be the absence of any of that.
OK, but the point is, maybe they would not have said they were interested in science and then talked about Newton's laws! That's what you have to include in your calculations. I have had some small success getting people jazzed about Newton's laws, but the fact is, it's just a lot harder-- the number of people who are going to feel that way is just less than it is for the wilder stuff. That I believe is Dr. Cox's primary motivation for his subject selection, not the desire to feel smart.
It is simply not an either/or propositon.
And there's certainly some truth to that. This is a valid criticism that can be raised, but it doesn't make what Dr. Cox is doing worthless or damaging to people's minds, they come to it because it gives them something they like, and it is certainly connected with science. I think it does a lot more good than harm, and if it could be improved in some way, who among us could escape that criticism? None of this justifies that vitriol, even though there are valid aspects to the points you raise.

SecularSanity

And thank you for the reply.

Sorry, but I couldn’t resist. However, I’ll refrain from linking the video.

You’re young, handsome, and your accent makes you sound intelligent, but here’s some womanly advice. Critics should cover their own butt and stick to the bare necessities, don’t cha think? What’s up with the banana?

Thanks again.

Cheers!

unusualname

There are several science programs on bbc tv and radio, some more populist than others. Brian Cox's are more at the entertainment end of the scale, but I for one quite enjoyed the four episodes in The Wonders of The Universe series, for example (even with the ott music in the first series of broadcasts).

The target audience is certainly not elitist types, and you should probably avoid these programs if you have 'a stick up your bottom' attitude to such populist science.

There're always the online lectures of Susskind for example if you want a dry Diracesque introduction to QM. Feynman's style can be seen in the Messenger Lectures http://www.microsoft.com/education/f...&c1=en-us&c2=0 (requires silverlight - microsoft compatible only) , I personally doubt his double-slit lecture (lecture 6) will enlighten the uninitiated any more than Cox's attempts.

cpsietc

I am still surprised by what was said about the consequences for electrons throughout the Universe of warming a diamond in one's hand. For a start, diamond is an electrical insulator with a large energy gap of more than 5 electron volts whereas the average thermal energy of an electron at room temperature (3/2 kT) is only 0.04 eV. Increasing this by at most 5% falls far short of the minimum needed to cause any electrons to jump into higher energy levels (assuming the "box of carbon atoms" contains no impurities); it will just cause the atomic lattice to vibrate a bit more.

Ignoring anomalies (if any?) caused by relativistic effects such as electron creation and annihilation or the lack of any FTL signals, the Pauli Exclusion Principle does of course hold for all electrons everywhere, regardless of whether they are pictured as bound to nuclei, zipping along on their own at almost the speed of light or just drifting about in a plasma.

The double-well example is fine as far as it goes, but only bound states corresponding to fixed separations of the wells are considered. In a gas, unless two nuclei are part of the same molecule, they will not usually remain a fixed distance apart and therefore will not give rise to a set of stationary states with exact electron energy levels.

I think I'm right in saying that at present, the conventional view of astronomers is that a good 90% of ordinary (baryonic) matter (nearly all H) is in the plasma state. If this is correct, then around 90% of all electrons are not bound to any nuclei at all!

When two of these "free" electrons are in relative motion, there could always be some inertial observers for whom their energies are equal alongside others for whom they are unequal. Therefore, I do not see how it is possible in general to substitute rules about electron energies for the basic requirement of antisymmetry of the electron component of the total wave-function, a property which is both observer-independent and permanent.

I agree of course that quantum mechanics does imply that "everything is connected to everything else" through entanglement, but I don't think the scenarios chosen to illustrate this amazing idea were at all convincing.

pds

If it is the case that electrons occupy slightly different energy levels, then wouldn't it follow then the spectra would show similar subtle variations? In Chapter 11 of the Quantum Universe, it mentions the "Lamb Shift" and this is accounted for by factoring in particle interactions within the atom. Wouldn't this Lamb Shift be undetectable if there is also a certain "arbitrariness" about the actual energy levels? Or is it a question of scale? Or maybe, I haven't understood!

mc^2

If all the electrons in the universe have to be in constant communication to ensure that no two of them are ever in the same state, then this may contradict the principle of conservation of energy. If we control a material in such a way that it's electrons would occupy most of the lowest possible energy states - this would indicate according to Cox explanation that all the other electrons in the universe would have a lower probability to occupy these lowest energy states and a higher probability to exist in higher energy states. This cannot be correct.

Ken G

I'm sure Dr. Cox understands conservation of energy. His viewpoint is simply that if there is a probability that an electron will be in an energy state, this affects the accessibility of the state, so if I remove energy from an electron such that it would have a higher probability of moving into some state, and there is already some probability of an electron being in that state, the fact that all electrons are entangled (by their indistinguishability) implies that they are all "affected" in some sense. I think the real problem here is that Dr. Cox's words are being overinterpreted-- the key point is that electrons are identical, and thus entangled. Hence, any counterargument that first pretends the electrons have separate identities is already missing the point. Perhaps he was not careful to make this distinction-- it is crucial that all language like "this electron" or "that electron" be avoided when one is discussing Pauli exclusion.

mc^2

"I think the real problem here is that Dr. Cox's words are being overinterpreted."

I agree; the real problem is to try to find the right words to describe the situation in terms of a layman's frame of reference while minimizing the possibility of misleading them.