Eise

List of unsolved problems in physics

Well, this seems more or less a semantic discussion. I just like, for clarity of discussion, to distinguish between singular facts (true descriptions of events) and correct theories (that are abstract, i.e. do not contain any singular facts, but with specific initial conditions can be used to predict events).

I agree, when you talk about 'the truth'. Or better 'The Truth'. But I think that in in established scientific theories we find many 'truths'. If it turns out that QM is not complete, it will hardly effect the fact that we can e.g. recognise hydrogen by the Balmer series. And airplanes will not fall from the air because QM is not complete.

So it could be that we discover tomorrow that objects that fall on earth will not fall according to our present knowledge? That's why I like to distinguish between scientific theories in general, which might be speculative (e.g. tested in a limited number of cases, or not even that), and established scientific theories, on which e.g. we base our technology, and are even prepared to bet our lives on it. Would you not fly on a modern airplane, because QM might be false, and as computers are based on QM. and planes are completely dependent on computers?

Well, I personally think that in QM we are at some kind of end. In this case the end is that we cannot look behind our measurements. That would be a contradiction. To understand what 'really' happens in EPR/Bell situations is a question that asks to go beyond what we can observe. And that is a dead end per definition. We can only accept what the equations of QM predict, and find situations in which we can use them for even more astonishing feats than the EPR/Bell experiments themselves: topics like quantum computing, quantum encryption, 'teleporting', quantum erasers, experiments to observe quantum effects on scales visible for the (nearly) naked eye, etc come to mind. But these are all applications from the same underlying principles. Sorry this gets at your head now (I've seen this use of 'facts' already more often by other posters here ('Evolution is a fact')), but I hate this kind of misuse of the word 'facts'. Facts for me are true descriptions of concrete events, occurring at a certain place and time. So science is based on facts, but its results are theories: abstract descriptions of classes of events. Science can err on many places. To name a few: it may have its facts wrong (i.e. wrong descriptions of events), it can have plain wrong theories (phlogiston), or it supposes that its domain of application is bigger than it in fact is (classical vs relativistic mechanics). This third category is what concerns us here: with the relative small masses and velocities in daily life we get our facts right within measurable limits. So classical mechanics is still valid, but as a limit of relativistic mechanics. Now it is my educated guess that the situation for EPR/Bell situations will turn out to be at most such a limiting case (valid based on the specific values of our parameters), but even more probable, as I argued above, really the last word. @String Junky: Now, can you rewrite your post, based on a better usage of the concepts of 'facts' and 'theories'... Really? I think there is more than just 'usefulness'. To be honest, I like the 'truth aspect' of science very much (e.g. like the topic at hand), but I am less enthusiastic about the ways it is useful (atomic bombs?). But that would lead to a totally different discussion. Matter of taste. GR explains why we believed Newton was correct: in the limiting case of low speeds and masses we get Newton's equations. Hmmm... If you would have written 'Truth' I would agree with you. But I would defend that science has found many 'truths'. With established scientific theories applied to their domains of validity, we can predict events, given initial conditions. I think that is as close to 'truth' you can get. In natural science, knowing the causal role of its objects, is knowing the objects. Science should not pretend more, but surely also not less. No, definitely not. Lawyers apply man made rules in such a way to gain maximum results. Philosophers try to clarify our way of thinking in different areas, scientific thinking being one of them. Maybe you are thinking about old-fashioned metaphysics, in which is speculated about how the world is 'behind the scenes'. But, again per definition, this is doomed to stay speculative, because in science we deal with the scenes themselves, and therefore can observe and experiment. If we could do 'metaphysical experiments', then it is not metaphysics anymore, but science.

Not that I am aware of. But being the antiparticle of the neutron, one would expect that its lifetime is the same as the neutron.

I fully understand the problem with the coffee... Hmm... A matter of taste, I presume.

Aren't you mixing up the cosmological constant and the Hubble constant? So I would say the cosmological constant was re-introduced. Well, one should be fair to Lemaître. I don't know if he liked the idea of an expanding cosmos because his theology. But when the pope declared that the proof was there that the universe was created at some moment in time, Lemaître warned him: knowing how science can change when new observations become available, science could eventually prove that there was no such moment, making God's creation a scientific topic. Maybe one could see Lemaître as a early adopter of the NOMA-idea (None Overlapping Magistra): science and religion have different domains, so they cannot conflict.

What does 'believe Hubble' mean? He was the one that discovered that the universe is expanding, based on observations, and that was confirmed many, many times. It was also predicted just a few years before by the Belgian priest Georges Lemaître, based on Einsteins equations of general relativity. So what does 'Einstein was wrong' mean? As others already explained, the Einstein equations do not allow for a static universe: it must be expanding or shrinking (yes, not just shrinking as you suggest). It was Einstein's belief that the universe would be stable, and a way to reach this was by adding what he called the cosmological constant. That, but only that, was his error, as he honestly admitted when Hubble did his discoveries. But Einstein's best known theories, the special and general theory of relativity were confirmed many, many times, and are used on a daily basis in modern technology (GPS would not work if we would not account for the effects of special (movement of the GPS satellites) and general (effect of gravitation) relativity). You know, science is not religion: it is not the case that science just believes what great scientists said. Their theories are tested and tested again, and eventually applied in technology. Also they are further developed, and applied. Einstein was sometimes wrong in his applications of physical theories (expanding universe, interpretation of quantum physics), but the theories he (helped to) develop(ed) are standing all empirical and theoretical scrutiny. So anybody claiming 'Einstein was wrong' means just one of his 'blunders', which are generally accepted as real errors (some of them already by himself), and that is of no importance, these are interesting footnotes in the history of science. Or he means his big theories are wrong, but then he forgets that these big theories are proven right again and again, and applied in our technology.

Ehhmmm, no. It was meant as QM-Spin. Maybe the misunderstanding lies here: you think that I said that the spin measured can be 30o, 45o, 55.3977o, , but I said 'in which direction we measure the spin'. Instead 'up' of down', maybe one should use 1/2 and -1/2. So I have my measuring device under different angles, and measure the correlation between the other, also under different angles. As examples: Measurement Angle Device 1 Measurement Angle Device 2 Correlation 0 0 100% 0 90 0% 90 90 100% 0 45 55% (The last percentage is my invention). Does that clear it up?

Thank you. And glad you didn't spoil my joke this time!

As Strange already noticed, there is no faster than light 'communication' involved. What is the case is that those experimenters showed you can derive which colour balls are at the remote side, by measuring the colour of the balls on their own side. Of course it is more complicated than that in this experiment, but it is the basic principle. But here is a thought for you: if those experimenters do not understand entanglement, why then were they able to do this? And also, there are already more technologies based on entanglement. How could these technologies be developed when nobody understands entanglement? No: the mathematics of entanglement is clear and unambiguous. The only problem for us is to picture how the correlation in QM can be stronger than classically possible. No. What you have in your pocketsess is a fact that I cannot derive from theory: it needs an observation. Obviously you do not understand the difference between simple observations and established (in the case of entanglement) scientific theories. And I don't know everything about the beginning of time. But I do know a little which cosmological theories are more or less established, and which ones are still (very) hypothetical. There is no problem that the time between the measurements can be infinitesimal small. Compare with the red/green balls: how short can the time be between me opening my box, and the alien opening his box, and we still see that the measurements are correlated? Again you suppose that there is causation between my measurement and that of the alien, but there isn't. There is only correlation. And this does not violate physics at all: that entanglement should exist was first derived theoretically (Bell's theorem). But in those days technology was not developed enough to really test this. Only one or two decades later, the experiments were done, and they succeeded: these experiments proved, that the understanding of the theoretical physicists was correct. And now you say that nobody understands entanglement? Entanglement is a very clear case where first there was the theoretical prediction, i.e. the understanding, and then the confirmation by experiment.

Sigh... One of my, call it didactic, principles is trying to explain as simple as possible something. For this it is essential to see where the person to whom it is addressed stands in his understanding. In your case, it is very low. So I very slowly built up my explanation. Anyone interested in it would appreciate it, I hope (I am afraid that the points I got are by people who already understand entanglement). But sometimes somebody comes along who thinks he understands these things better, and does not want to learn. So this was a pearl for the swines... But if you know better, explain to us how it can be done! We are listening! But if you say that it is a secret, and therefore you do not know, we know all what you really are... So please explain how entanglement can be used to send message faster than light.

So if I change the charge of one plate, somebody can measure an instantaneous change at the other plate. Wouldn't that be a violation of special relativity? @Menan You show that you do not understand entanglement. Let's go one step at a time. First a classical example. I have a bag of balls, they are all red or green. Without looking I pick two balls, and I put them in separate boxes. I keep one, and send the other far away. Then I open my box, and see it is a green ball. What can I conclude about the colour of the ball in the remote box? Right, nothing. And why? Because there was nothing special with my picks. It could have been two reds, two greens, or one red and green. Now I pick, looking of course, one red and one green, and put them in two separate boxes. So what I did here is 'entangle' the balls. Now I shuffle the two boxes, so that I do not know which one is which. If I open one, and see that it is red, I immediately know that the ball in the other box is green. And of course, this is independent on the distance. If I send the second box lightyears away, and only then open my box, I still know immediately what some alien sees when he opens his box. I know it because the observations are correlated. And the correlation already happened at the moment of my picks. That is the moment of entanglement. It is not when the boxes are opened. Now in quantum physics, there are processes where two particles pop out, which have e.g in one aspect always opposite values. Say the direction of spin. So if I measure the spin e.g. in a vertical direction, say it is 'up', then I immediately know that the other one will measure spin 'down', when also measured in the vertical direction. But as with the balls, the 'moment of entanglement' is when these particles popped into existence. But in quantum physics a few things are different: first, it is impossible to say which particle has which spin without measuring (it is as if I created the green and red balls, including their boxes, without knowing which ball is in which box). But as the two particles are entangled, if I measure both, the measurements will always be correlated. And there is nothing special with correlation: if I send one particle far away, and then measure my particle in the vertical direction, and the alien measures his particle in the same direction, I will always know what he measures: the opposite of my measurement. The 'spooky' aspect comes in when we do not know from each other in which direction we measure the spin. It can be vertical, horizontal, 30o, 45o, 55.3977o. What we find is that the correlation is stronger than one would expect if we would assume that the particles already had a definite spin from the beginning. But it still is correlation, not causation. As with the red and green balls, there is no direct causal relationship between my and the alien's observation. The causal relationship goes back to the moment of 'entanglement'. Everything afterwards is just correlation, and therefore cannot be used to transfer information. And because there is no causal relationship between my measurement of the spin of my particle, and the alien's measurement, I cannot use entanglement for sending information. And all this is very well understood by all quantum physicists, and is no secret at all.

Missed this... Ah..! The 'nothing but' operator! (Also known as the 'just', or 'nothing more' operator.) That means a piece of iron dissolving in sulphuric acid also counts as 'we'? In the end that is a chemical reaction too. So we can question if it is ethical to stop this chemical reaction, in the same way we can ask if it is ethical to kill somebody? Is a steam train 'nothing but iron, coal, and water'? Of course we do: they don't. Mind and brain are different views on the same processes in our brain. So there is no need to philosophise about how they are connected. Is the plain event of a runner crossing a line the cause of him winning the race? Or how is that event connected to him winning the race? Or is there just one event, seen from different viewpoints? Is it comforting to know that you get reincarnated as some lowlife, because of your bad life? (OK, you can reincarnate again and again, and have a chance of better lives some time. Might be better than eternal torture in hell...)

One could change your sentence in a way that it literally says the same, but completely changes its meaning: the mind and all her furnishings -- beliefs, desires, hopes, fears, even consciousness itself -- do exist, but not as commonly understood. Of course, the traditional science of consciousness is not very successful, and Dennett is pretty clear why: because our intuitions fail. Especially the intuition of the Cartesian theatre: dualists suffer from it, as do materialists denying that we have free will. That is definitely not true: his method of heterophenomenology is not behaviourist. That bon mot is found everywhere on the internet. Depending on how you understand it, it is true and false at the same time. Take one of Dennett's early favourite examples: a doctor explains the effectiveness of sleeping pills because it contains vitus dormitiva. Did he explain anything? Of course not. Explaining the workings of the sleeping pills must be build on lower level mechanisms. With consciousness is the same: trying to explain it with conscious subelements means that you did not even start explaining consciousness. At most you are are building up a phenomenology of consciousness. (there is nothing wrong with such a phenomenology, but it is no explanation of consciousness). So explaining consciousness means to explain by processes that are not conscious themselves. And where this principle is accepted in nearly every science, when it is about consciousness suddenly people raise up, complaining that consciousness is explained away. So, yes, the bon mot is true in the sense that every explanation is sort of explaining away, but it is false in the sense that it is a real explanation. Life is not explained away by pointing to the fact that life is 'nothing else' than a very complex chemical process. The 'nothing else' however is very tricky: one could understand it as 'chemical reactions are not life, so it means life does not exist'. Those who say Dennett 'explains consciousness away' do the same with Dennett's theory of consciousness. Do you really think that Dennett would say consciousness does not exist? If John Searle thinks Dennett denies consciousness, then he is wrong. I am pretty sure Searle does not understand Dennett. And as he is still sticking to his faulty 'Chines room' intuition pump, he is disqualified in my eyes. I think this is the whole point: the answer on the question depends on how you define 'sound': is it the vibrations in the air (then yes, the tree made a sound); or is it only sound when it is heard (then no, the tree did not make a sound). Philosophers should be trained very well in shifting of meanings of words. I notoriously get into these kind of problems when discussing e.g. free will. I can explain a hundred times what I understand under free will, but when arguing I soon observe that my 'opponents' return to their own meaning. Their intuitions about what free will is supposed to be are so strong, that they cannot leave it behind in understanding what I am trying to say. Dennett has the same problem with explaining consciousness: the intuition of the Cartesian theatre is so strong, that even when people understand the notion, when evaluating Dennett's arguments they unconscious (!) they fall again for the illusion. And as a real life example in this forum: ask Koti about see1 and see2... He probably gets a nervous breakdown when he reads this... Did you read that somewhere here? Or can you recognise my Dutch accent from my writing??? Pity for you I do not live in the Netherlands anymore. So no Grolsch, sorry. But you are right it is much better than Heineken and Amstel.

I don't think he made such terrible 'gaffs' (new word of the day for me ). As far as I remember you did not understand the point Reg was trying to make. But I do not want to recap the whole argument again here. As far as I remember the discussion was about naive falsificationism, which nearly nobody adheres to anymore, except maybe a few naive scientists. I know that it can be difficult to keep calm at Reg's posts, because of his 'know-it-all' and cynical style, but if you feel angry because of that, just take a deep breath, and concentrate on the contents. Are you sure you understands what he says? If not, ask. If you are, give counterarguments; but do not dismiss them just out of hand. Philosophy is not trying to dismiss the other, but proof the validity of arguments. In my impression the threads were not just closed by Reg's tone, but also by those of others. Any discussion, be it in science, philosophy or daily life, is done best by taking a disinterested stance, by not identifying oneself with the arguments, and so feeling attacked when somebody does not agree with you. And again, @Reg Prescott, please temper your tone. It could be much more productive.

I have no idea what Dyson has to say that would debunk Swansont's 'belief system'. Unless you are interested in the man, it is not very interesting. I am, a little, so I watched the video. The main 'shocking point' is that Dyson sees no reason why GR and QM should be reconciled. I did not find it very convincing, but hey, I am not a physicist. I just know that hordes of physicists do not agree.

Sorry that I have not so much time to chime in. I have a lot of other stuff using nearly all my energy. Then there is not so much time for deep thoughts. But I could not let this pass: Dennett is definitely not a behaviourist. It seems to me you have never read something from him. Maybe just about him. I could not find an online version of it, but maybe you can find it: "Skinner skinned", from Dennett's book "Brainstorms". For the rest, I feel as if I am in a time machine flying back to the days I studied philosophy. I already forgot (not in this thread if I am correct) the distinction between 'intention' and 'intension'... Great you brought that back to me. Just some fast shots: I recognise a lot of your thoughts, and, as info for the others, Reg is using standard terminology in general accepted philosophy, and his ideas are not extreme I can imagine that it is difficult to see where Reg stands: maybe it helps to see that Reg is not attacking science in itself, but more the accounts many people have of understanding what science can accomplish, and how it accomplishes it. It is about what knowledge means, what truth is, what facts and theories are, etc. It is notoriously difficult to give an account of the relation between language and reality (and what latter exactly is...). As science must use language (even if it is 'just' mathematics), the difficulties in this respect work through all the way to science. It might even be impossible to give a consistent account of the relation between language and reality. (Because such an account must be given in language...?) And as a hint to Reg: I suggest you slow down a little, you overwhelm people here with a torrent of philosophy. And it might also help to be patient and polite. Let the irony and cynicism be. I think it would be a pity if your threads always get closed.

I'm not sure that is a useful example. After all, particles have momentum (and waves have position). But it does, perhaps, relate to the fact that the uncertainty principle is based on Fourier transforms between the two things being measured. Agree with you, Strange. I even think that Itoero's expression does not make sense, because it suggests that there is a 'real' wave that at the moment of measurement becomes a 'real' particle. And your remark about Fourier transforms: here is a wikipedia article about it.

Oh, my. Where has this discussion gone... If this way of discussion would be representative for what philosophers do, I tend to agree with beecee's stance on philosophy, with his many times repeated quote of Mencken. I learned first to understand exactly what the position of the other is, before showing weaknesses in that position, or bringing one's own. Really, it is possible to do philosophy in a civilised way. But if people feel their 'holy houses' are attacked, and react from their hurt feelings, it is inevitable that a discussion regresses in a discussion about who is right. I am sure Reg makes some valid points, and so do others. Happily enough, most of philosophy is not like this. To say it in line with Mencken's quote: some philosophers behave like that, some don't. Sounds a bit like Reg's distinction between 'Science' and 'scientists'... Please do not generalise... Just one question: do some scientists engage in a quest for reality, or do these scientist believe they are engaging in a quest for reality? What is the real question at hand here?

I am not so much in the science of hypnosis, but it at least makes some sense to me. I once did a small course in hypnosis during my studying at university. Some elements were to strengthen certain thoughts, by using suggestive imagination, to improve memory by using images and a few more. As special 'last session' we did a regression (=reincarnation) session. I was the voluntary. As usual we worked with images. At some moment there arose an image in me, clearly not from my life, and I did not like it. Against what many people believe, during hypnosis one is still fully aware of what is happening inside and outside you. And because I did not like the image, I decided to wait until some other image would come. But there came none. So rather unwillingly I started to describe the image to the course leader and my colleagues. So it really seemed my critical, fully conscious thought had not much to say in the matter. Looks like the 'bottom-up' situation you describe. Another observation: there was obvious anger in the story I told, and at some moment the course leader invited me to express my anger: one of the things I did was clenching my fists. But afterwards, coming out of the relaxation of the hypnosis (which took about an hour), I only could start moving very slowly. Impossible to clench my fists immediately! For the record: I do not believe in reincarnation. I explain my session as finding images that fit best to the feeling I had at the moment. I even think that I know where some of the images came from: some movie that impressed me very much, creating then my own story around it. But I can imagine that for many people it feels very real because one is very focused on what is going on in one's mind.

I think what Darwin is saying that organisms in the process of natural selection only become good enough for their environments. Otherwise they would become extinct. But there is no drive to go beyond 'good enough', or if you want 'sufficient perfection'. The comparison with divine creation seems to be Sober's interpretation. I have a stance, but it is not deeply thought through. It is definitely closer to scientific realism than antirealism. Semantics was never a main topic for me. So I hope I do not dissapoint you with my reactions. No, I explicitly said that the concept of 'unicorns' is not empty. Otherwise the sentence 'unicorns do not exist' makes no sense. We all recognise a unicorn immediately from some drawing or painting. But at the same time we know there is no such animal in the 'real world'. I would subscribe to this view. Dalton rightly recognised that there must be smallest particles of each element, each particle of one element being exactly the same, and that compounds are combinations of these particles. To say something is the same as another is always under a certain aspect, leaving out some others. E.g. the modern idea of atoms does not imply 'undividable', which was part of Dalton's understanding. So there is a continuity from Dalton's ideas about atoms and ours, which makes it possible to identify the concepts with the same objects. I seriously doubt that we could do the same with e.g. Demokritos' atoms. (But are not even sure). Don't be too sure. In the end I have a degree in philosophy... I think it is rather the tone from the discussions between Reg and several others that creates the problem. I thought about chiming in the thread 'Challenging Science', but then the thread was closed. Reg had a few valid points (but others had too). The discussion was more arguing that the other is an idiot than an intellectual probe in the supposed dogmatism against openness of science to changes of its ideas.

Uih.. it is a long time ago. I interpreted the phenomena as the possibility of dying: my heart beating strongly, and not being able to move. Maybe (but now I am already interpreting) I did not breath when I woke up, realised that after a while, and then started breathing consciously. I do not remember pain. Sorry I can't tell more. It is about 25 years ago.

You have a tendency to spoil the jokes of others...