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About Eise

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    the old world
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    Physics, Astronomy
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    University degree philosophy, subsidary subject physics
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    Database administrator, a bit of Linux too

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  1. Yes, you must distinguish between truth1 and truth2... Just kidding. To be honest, I do not like the substantive 'truth', even less when written as 'Truth'. I think the first thing is to look on which 'objects' the adjective 'true' applies: these are propositions, or complete systems of propositions, where I think about e.g. scientific theories. What it means is that they fit to what they describe. If they do not, they are false. (Or they are meaningless ('colourless green ideas sleep furiously'), or they do not describe a situation unambiguously ('One cannot see light' )) So simply said, one can define 'truth' as the correspondence between a description and reality. So it characterises a relationship between propositions and facts. Which e.g. means the 'Truth' is not out there. We find out if a proposition is true, if we find out that the description corresponds to reality. It is an attribute of propositions ('in there') and reality ('out there'.) I think this meaning of 'true' is simple. But that does not mean that it is easy to find out which propositions (or theories) are true. The two topics should not be confused: what 'true' means on side, and how we find out on the other. I think that some of the examples given are wrong: e.g that about simultaneity in relativity. Are two events simultaneous or not? Well, we know exactly how this depends on from which inertial frame you are observing these events. So we have to amend it to 'for observer A the events are simultaneous, for observer B they are not'. If we know how the perspective has influence on what people observe, then we know that there is nothing to quarrel about. It is as if two people are facing each other, and quarrel about the question if the chair stands at the right or at the left. If you take the perspective in account, the whole problem has vanished. Same with what is true today is false tomorrow. If it was an 'eternal truth' (something like F = mv, like Aristotle thought), and today we know it is false, then it was false all the time. We erroneously took it for true. But truth hasn't changed, because reality did not change. Same with the opposite: reality changes. It is drizzling. It is really true! I see it when I look out of the window! But of course this event is local: where I live, and am now, it is drizzling. It makes no sense to quarrel about the truth of 'it is drizzling', if I do not take the context in account. When I am going somewhere else tomorrow, then it is still true that 'in Switzerland at 17.03.2018 16:30 local time, it is drizzling'. Even if it is beautiful weather at the place where I am tomorrow. Personally, I would prefer to separate some concept pairs: For factual knowledge, 'true' or 'false' apply, because there can be a kind of correspondence between factual propositions and reality For morality, I would use 'right' or 'wrong'. There is no way that science can find out what is morally right or wrong. It can help if facts play a role in a moral decision ('if you do this some people might be killed, if you do that, the risk is negligible'). But this already presupposes that both agree on the norm that killing people is wrong. For aesthetics it becomes more difficult: beauty, interesting, fascinating or ugly, boring, ...The difference with morality is that it has a very strong personal factor. The compulsion to come to an agreement is less than in morality, but do not underestimate the intersubjective character of these aesthetical norms. If these is a discussion on how to renovate the old city centre, it can become very important that people agree. Well, then they are wrong. Truth is not subjective. Beauty has a strong subjective side, morality less, but truth is definitely not subjective.
  2. Moving at the speed of light

    Did you read your own linked article? If you have any questions, please ask.
  3. Not so absurd as it seems. The acceleration is not essential. Essential is that the spaceship changes its inertial frame. That makes the situation asymmetrical. Of course this implies, when you try to make the example more realistic, that the spaceship accelerates (at least at the turning point). Adaptions to the twin paradox have been made where nobody returns to the earth, but that one spaceship flies past the earth (with its 0.8c) to Alpha Centauri, where it meets a spaceship that flies in the opposite direction, also with 0.8c (compared to the inertial frame of Alpha Centauri anf the earth). So no acceleration is involved, but if you add the times of the two flights (according to the spaceships themselves) then during their flight times more time has passed on earth. If you look at the explanations at Wikipedia, you see that often acceleration is neglected, e.g. this one: But the difference in time still exists. Later in the article more realistic scenarios, with acceleration, are presented (which makes the math a bit more complicated, of course).
  4. Is that really a problem? You just must be sure that the definition you use for your unity (kilogram, meter, second, whatever) is defined in such a way that it can be measured in the same inertial frame. Why would this be 'more fundamental'? On one side, we know the relationships between many physical parameters (Newton's law, Ohm's law, etc). So we can 'span' all possible dimensions based on different 'basic vectors'. But when e.g. it is easier to make an experiment for exactly determining what 1 Ampère is than what 1 Coulomb is, then of course one would take Ampère as basic unity.
  5. I assume that even in the cgs-system, adding inductances and lengths, or EMFs and ergs does not make sense... For those who understand what it is all about (I do not quite), the Wikipedia article about the cgs system describes it all.
  6. It is rubbish. Others already mentioned how the author has his science wrong on quantum mechanics. I can only second these arguments This of course is a nonsense argument: Where did Einstein say that death is an illusion? There is a huge argumentative gap between 'the distinction between past, present and future is an illusion' and 'death is an illusion'. The world is not exactly timeless and spaceless. It is only that space and time are intertwined in an exact defined way according to Einstein's special relativity, and therefore is called 'spacetime'. But spacetime is another way at looking at events. It does not mean that events are illusions. And because death is an event, it is no illusion either. The whole article is New Age woo, worth nothing from a scientific viewpoint, worth nothing from a philosophical viewpoint.
  7. As this seems to be important... The meaning depends on the context. One way to see this is that you can change the '=' into '=>', in the other that is definitely wrong. But you mustn't. The problem could be given as: Solve: (x - 1) (x - 1) = x2 +1 - 2x So the 'derivation' would be: x2 +1 - 2x = x2 +1 - 2x So it is true for every x. (Why do I have faint memories of 'see1' and 'see2'?) Some already said it: mathematics is (amongst others) with dimensionless objects, e.g. numbers and vectors. So you can add x2 and x, because there is no dimension there. But still you cannot add 2 and the vector (1,2), because they also in mathematics have different dimensions. But in physics all quantities measured have dimensions: length, surface, mass etc. And here the same is true as in math: you cannot add numbers with different dimensions. The reaction equation: HCL + 10H2O = HCL(aq) + 16.61 kcal is just sloppy use of the '=' sign. Literally, i.e. in the mathematical sense, you cannot add molecules and warmth. But we know what is meant. The word 'equation' is not in the mathematical, or even in the physical sense. 'Allowed symbols in reaction equations are: Edit: OK, that citation does not quite work. Follow the link to see the symbols in their full glory...
  8. science is subfield of philosophy

    Yes. In the line of the discussion in this thread, and understanding the text about Feynman, it is. That is another topic. You can open a new thread if you want.
  9. science is subfield of philosophy

    But Feynman meant science here, not philosophy. And we are all physicists when throwing a ball, or when we bend over in curves when driving a bicycle...
  10. "Intrinsic angular momentum"

    Or Dirac. AFAIK spin (and antimatter) rolled out of his theoretical synthesis of QM and special relativity.
  11. science is subfield of philosophy

    In the end I had the time to read, and react on it. I like the article. It is interesting to see that Feynman (I would say of course...) surely has made philosophical ideas about doing science. So I would say that his disdain for philosophy is partially explainable by the (bad) philosophy he has seen during his excursion at the philosophy faculty. Instead he could have developed his own philosophy of science, contradicting ideas he thought stupid. That would have been a valuable impetus to the philosophy of science. Interestingly enough he touches at some (radical) ideas of Paul Feyerabend: Just two quotations I like, from your link:
  12. science is subfield of philosophy

    Well, if it is fully explained without particle interaction, then it is a typical case for Occam's Razor. A black hole has no corona, but light is bent, can be doppler-shifted, so whatever the effect of a corona is, we do not need it to explain the effect of gravity on light. Occam's Razor rules. It really seems you have no idea about what doppler-shift is. It is completely explained by the relative velocities of different inertial frames. No property of photons changes, but due to velocity differences, observers see the light with different frequencies. It is as if you want a physical explanation why I see a circle as an ellipse because I see it under another angle than 90o. To you maybe. But take care when you are creating your private language, especially in domains where most people more or less agree on the use of their words. You take the risk of being seen as a parvenu, defending standpoints that are wrong, until one discovers that you use words differently than most other people (I remember a discussion about the word 'theory', where you used it in a much more vague way than could be derived from the context of the discussion of that thread. And then I do not even talk about refraction and scattering...). What drives you to redefine existing concepts against the main stream of science and philosophy? What do you think is gained by that? Mastering of a language is to comply with it. Because it needs too much expertise in the theories themselves. On the other hand, such interpretations fit more or less to the old view on metaphysics: how nature is behind the empirical scenes. Such metaphysical ideas should be consistent with empirical proven theories. 2 Possibilities: Only one interpretation is possible: but then it is science. Empirical facts have decided what the correct interpretation is. More than one interpretation is possible: then it is not possible to decide which is the correct one, and the theory's interpretation could be called metaphysics. However: most philosophers, following more or less Kant ('Critique of pure Reason') have decided that metaphysics in this sense is an empty enterprise. Why bother about questions that principally cannot be answered? Therefore modern metaphysics is not interested in such questions anymore. (One could add that there is a third possibility: No interpretation is possible. This stance is also defended trying to understand QM, e.g. the classical concepts of particles and waves are conceptually contradictory. Nothing can be a wave and a particle at the same time. This is more or less the Copenhagen interpretation.) Maybe superfluous to remark: there is a huge difference between interpretations and scientific speculations, or better hypotheses. First cannot be decided empirically; latter can. Therefore scientific speculations are definitely not philosophy. And because metaphysics in the old fashioned sense is 'out', there is here no role for philosophy to play.
  13. Light: visible or invisible?

    No, no, I am sure that was not the reason. Just stay on topic, polite and friendly, and you will have no problem being banned. Let's test if I get banned: As most people here say that it is a semantics question, so not an empirical one, it is not a scientific question at all. It is a philosophical question. Seems we plead that the question belongs to our domain of expertise: one says it belongs to physics (where we still are), you say it belongs to neuroscience, and I think it belongs to philosophy. Can't we all drink a beer together? (Ups, Cape town is far away...)
  14. Light: visible or invisible?

    Maybe you are right. But by making artificial new words I tried to keep emotional attachments to meanings of words out. It is a strategy that most of the time works, but not with everybody, not always... Yes, that is one form* of 'change blindness'. Daniel Dennett describes his own experience, with him as guinea pig in such an experiment. The eye tracker was attached to his head, and when he felt OK he said 'you can put the system on now'. The answer was: 'it is already on, Dan!'. *Another form of change blindness: tell me your experiences. How long before you discovered the change? The short 'break' between the two pictures is the equivalent of the saccades of the eye Does it? Let's make a (very!) primitive model of the visual cortex. It is like a screen, that assigns an RGB-value to every 'pixel' (nerve cell?) inside the limits of the visual field. Nearby the middle however, the 'pixels' do not get any signal from the eye, because of the blind spot, and 'no signal' of course means 'black'. That black spot has to be photoshopped away. Now a little less primitive model: there are no nerves from the blind spot (per definition) so there are also no nerve cells in the visual cortex that are eagerly waiting to get input from the eye, from the blind spot. Where is nothing, there is nothing. And where there is nothing, nothing must be photoshopped away. Being conscious of absence is not the same as absence of consciousness... (That one is not from me of course. Dennett again.) The same might hold for change blindness.
  15. science is subfield of philosophy

    What is philosophical science? Never heard of it. Something like Christian Science, but then based on philosophy instead of christian belief? If you have a scientific theory, like QM, and all agree this theory is an extremely good theory of empirical reality, how can one do then empirical research in its interpretations? I think that we should leave the interpretations of physical theories to those people that understand these theories. Mostly these are physicists themselves, not academic philosophers. And I, as an academic studied philosopher, have nothing against physicists 'going philosophy'. There is no guarantee that some good philosophy comes out of it, that should clarify itself in an ongoing discourse with other physicists and philosophers (but please philosophers that know their limitations...). Strange already gave an answer. But it surely is not democratically decided, and certainly you do not decide it. Let me just say that some topics in my academic study of philosophy were: history of logic (e.g. syllogisms), propositional logic, predicate logic, modal logic, argumentation theory; I even tasted some of temporal logic (which, I confess, was extremely difficult. I think only the theoretical physicists that were also attending the lecture were equipped enough to really understand it).