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Not that Swansont needs me to answer for him ... You must realize, Davy_Jones, that Physics treats the trajectory of a cannonball by considering forces acting on its center of mass, or center of gravity. That is, as a point mass. Is that your 'true reality' ??? We may not know much concerning Philosophy, but you have no clue about Physics ( nor reality, for that matter ). Maybe we ( actually you ) should start over, and, instead of being antagonistic and telling us what is wrong with our world view, try to learn from each other.

Really? I know a little philosophy and physics. Enough to recognise crackpots in both disciplines. And where Krauss surely is a good physicist (cosmologist?) at the terrain of philosophy he is a crackpot. Of course I stumbled over the few lines where he talks pejoratively about philosophy. But by the quality of the arguments, one recognises the value of these remarks: none. If you do not like semantics, then philosophy is definitely not your thing. So it once was true that sun orbited earth? But when it was true, i.e. a perfect fitting model of reality, then once the sun really orbited the earth. And it stopped at the day Copernicus came with his heliocentric model? Davy (and I) are not confused. We see how complicated it is to give a correct account what happens in science. And as said earlier, I believe that the problem is grounded in the difficulty to account for the relation between language and 'reality', i.e. what is talked about. I am not 100% sure if I can also speak for Davy, but it is not about the praxis of science, the value of its insights, or its undeniable value for developing new technologies. Science works, that should be clear. It is about the selfunderstanding of science. Do you know the true nature of anything? (I am afraid I don't). I think a better criterion for'approaching the truth' is the increasing domain of theories: Ptolemy was OK for predicting celestial observations (but we would never have been able to send New Horizons to Pluto...), with Kepler the picture was greatly simplified, with Newton a connection with earthly phenomena was made (same explanation for falling objects and orbiting celestial bodies), and Einstein, making gravity Lorentz invariant (if this is a good description of GR) was even able to predict new phenomena. What we see is continuing extension of the domain of application theories. One could say, the more encompassing a theory is, the better it is. But if that means that we are 'closer to the truth' would suppose that we know there is some truth out there (how would we know that) and we are closing in. Another kind of example: we have a very extended theory of the electron. We know how it behaves in all kind of situations. It might be that there is nothing more to add to it. Suppose this is the case, do we then know the true nature of the electron? I would translate that, conform my musings above, that we know we do not have a complete theory of gravity: GR fails for the centre of black holes and the big bang. But when we have one (empirically validated), would we then know the true nature of gravity? Or are we a bit more humble, and say we have a pretty good understanding of gravity, because we can calculate through every possible situation we know of in which gravity is essentially involved?

Agreed it is 'reality' and 'true', which are the problems. Neither are scientific terms. Both Science and Philosophy have a commonality in that they have both developed a discipline specific language, terminology and symbolism. But that is as far as it goes because many if not most of the concepts these refer to only occur in their respctive disciplines. What I see happening here is the attempt to apply the language, terminology and symbolism of one discipline to the language terminology and symbolism of the other. It is not suprising to find that therefore that this fails because for instance the 'reality' and 'truth' of Philosophy, have no counterpart in Science.

So far this has been a very interesting, informative and often over my head discussion! Some great posts from the resident experts and our honoured guest! Being a Layman (or at best a novice) I have limited understanding of the subjects I enjoy, space-time, gravity and the speed of light. Reading through the posts, the discussion has often diverted off track from the original post. One of the diverts was the semantics of terms and phrases. One which I commented on way back in the discussion as a sort of dismissal. Since then I have come to realise that in fact the importance of the usage, meaning and context of some terms and phrases used have a profound effect on my preconceived understanding. In pondering the original post - "Is gravity a force?" and the phrase so often used - "the force of gravity" I started to consider the meanings behind both. The force of gravity: The interaction between 2 or more objects resulting in a mutual attraction - Newtonian The curvature of space-time - GR (Einstein - preferred model) These 2 descriptions appeared to me to be conflicting. Then I had the idea to split the phrase into 2 terms - gravity & gravity force. Gravity - space-time curvature Gravity force - the interaction between mass, space and time From this I realised that we are dealing with 2 separate, but related entities - cause (gravity force- interaction) and effect (gravity - spacetime curvature) So, based on this premise, going back to the original question - Is gravity a force?, makes no sense, rather the question should be - what is the gravity force? or, to stick with the often used phrase, - what is the force of gravity? WARNING! wild speculation and imagination alert!!! - So considering gravity within this new context, I had no problem imagining a consolidation between GR & QM model's of gravity. In my imagination I consider the "force of gravity" to be a quantifiable interaction between space- time and mass where the interaction is.. , maybe using force carrying particles (gravitons) similar to the other kwon forces within the standard model. In GR the math describes the possibility of singularities forming at the extreme small scales and high densities. In my imagination, at such scales the force carriers become intensely active, however are unable to operate below the Planck scales. Such that this tiny region of space is just too small for force carrying particles to operate in. Therefore the curvature of space-time ("mutual attraction") ceases to operate at Planck distances, resulting in the impossibility of singularities forming. So I can image at the centre of BH's for example an object extremely dense, extremely small but larger than a Planck volume.

I like van Fraassen's anti-realist position of "empirical adequacy," which @Davy_Jones has acquainted us with. From SEP.... In contrast, the constructive empiricist holds that science aims at truth about observable aspects of the world, but that science does not aim at truth about unobservable aspects. Acceptance of a theory, according to constructive empiricism, correspondingly differs from acceptance of a theory on the scientific realist view: the constructive empiricist holds that as far as belief is concerned, acceptance of a scientific theory involves only the belief that the theory is empirically adequate. This sounds to me how a lot of scientists view their work. A theory is empirically adequate, but few would mistake it for a declaration of metaphysical realism. What is a wavefunction, really?

How is this different from my position that science describes behavior (i.e. what we can observe) rather than reality. (something you balked at)

That doesn't really mean that someone is on to something. Crackpots hit a sore point with scientists, precisely for the opposite reason.

Yes. And please, no funny meant bon mots anymore. I think it is a word, but I am not a native English speaker... And yes, many people have their philosophical phases, in which they reflect on their basic assumptions. I don't see any pedantry here. (Except maybe someone who thinks he contributes to a discussion by dropping (the same) bon mots again and again). And philosophy (and most of the sciences) are impossible if we do not clearly define our concepts. 'Beliefs' can be true or false. Knowledge is true as per definition. So you correctly use 'belief' here: You said that we that 'we still do not know the true nature of gravity'. Which implicitly means we might one day. But how will we recognise we did? Therefore I introduced my example of the electron, of which we seem to know very much (Dirac equation, QED), of which Feynman proudly tells us that the anomalous magnetic dipole moment of the electron can be calculated until an unprecedented precision, and in the same lecture says 'this is how nature really works'. So, if there is nothing to discover about the electron anymore, do we know its true nature? I ask you, because you seem to adhere to the idea that we can know the true nature of (at least certain) things. I expect arguments (this is the philosophy forum!), not just be mentioned pedantic or a semantic ant fucker (OK, last two words are mine, but I assume you know what I mean.) There certainly exists a spectrum of opinions on what exactly science 'delivers': knowledge, models of reality, descriptions of reality, truths, insight, just calculation tools, etc. It is clear as day that different views about it also exist under physicists. Or even worse, some people might even speak with more than one voice, not noting that these voices are contradicting each other. And then such a irritant philosopher comes along and points them at that...

Yet you cite the scientific method with all the zeal of a priest citing the bible. You understand your bible in much the same way as a priest does, it's what you've been taught, not what you've learned for yourself.

I think the problem is that many physicists think about old fashioned, classical metaphysics. If you read a history of physics (and/or astronomy) you partially read about the same bunch of people as when you read a history of philosophy: Thales, Heraclitus, Plato, Aristotle, ..., Kant, just to name a few. There we have explicit 'explanations' about the physical world, and in the light of modern physics they are mainly wrong. On the other side, there are philosophers who seem to think that they can talk about physics as peers of real physicists. That can cause some irritation with physicists of course. And then there are the irritations here in the thread, and having a background in philosophy and in physics (a background, @MigL, I am definitely not a physicist (as I use to say, I am at most a 'half-cooked physicist')), I would say that beecee does not understand what exactly you are aiming at. Again and again he comes with the same (kind of) 'bon mots' about philosophy, that are taken out of context (Russel), are just nice sounding one pointers (Shaw), or have themselves no idea what modern academic philosophy really does (Krauss). @beecee, for all clarity: Davy is not aiming his arrows at science itself; they are aimed at its self-understanding. And this self-understanding is hopelessly naive in the 'shut up and calculate camp'. The other camp, that of the 'what is it exactly all about camp' have an inclination to become philosophers: reflecting on basic premises and methods of their science, eventually developing new concepts or methods. And there philosophers can learn just as well something from these kind of physicists as some physicists can learn something from philosophy. It's not all just black and white.

Tensor analysis. A very complete classic book of which affordable paperback editions exist: https://www.amazon.es/Tensors-Differential-Variational-Principles-Mathematics/dp/0486658406

It is tensor calculus, and differential geometry. Perhaps it would be better to start with Special Relativity first, which is simpler, and work your way up from there.

No, the IPCC reports were more conservative in the past, not less, with more care to emphasise uncertainty over confident and unequivocal statements. The hockey stick "controversy" was never a real controversy and Mann's early modeling has been confirmed as close to the mark. Multiple independent studies confirm the fundamental nature and existence of global warming, including hockey stick like change. Al Gore - not a scientist - speaking of worst case possibilities that haven't eventuated is not good reason to doubt the veracity of mainstream climate science - not when the most likely possibilities have eventuated, and those are as serious as was claimed. Questioning whether climate change has a net positive or net negative or where some kind of sweet spot between harms and benefits might lie has been tried. But you will struggle to find conservationists/environmentalists - and a great many ordinary people - for whom the remnant natural ecosystems and species have high value who will accept economic modeling that says the losses will be worth it. Adding 4 or 5 C degrees to already very hot and dry regions that experience serious droughts and heatwaves will have very serious consequences - adding that much to any region will have profound and serious and not entirely predictable outcomes. That kind of not being predictable doesn't make it more likely that no harms will occur greater, just makes the seriousness of the worst ones greater. Cost vs benefits studies have also been done in purely economic terms and the answer from credible ones appears to be the same; the disruptions from change will have costs impacting people now living, in their lifetimes, that no far future "better climate state" after they are gone can compensate for. And the potential for extreme outcomes with catastrophic outcomes remain real and in risk assessment terms, very high. So, if you find one claim - say that fires can't be clearly tied to climate change - does that make all the claims that have turned out right, like ice loss, ocean heat content rise, temperature rise, more frequent and severe heatwaves, more new hot temperature records broken and less new cold records - do you count the one claim as significant but all the rest not?

Speak of the devil . . . If you'll notice, in the sketch of "The Scientific Method" that beecee has posted above, one (supposedly) begins with an observation/question in the absence of any hypothesis. The hypothesis, we are told, comes later (Step 3). This is indeed representative of the "Baconian method" usually described as inductivism. On this account, one does not bring a hypothesis to the "raw, neutral, unladen-by-theory" data/facts; rather, we are led to believe, the theory is somehow already in the data just waiting to be teased out, so to speak. Charles Darwin, just to name one, was less than impressed . . . - Robert N. Brandon, "Concepts and Methods in Evolutionary Biology", p147 also . . . - Charles Darwin and just one more . . . - S. J. Gould, essay "The Validation of Continental Drift", found in "The Richness of Life", p 291

My favorite historical tidbit regarding the scientific method is that Francis Bacon may have died from conducting a scientific experiment in the preservation of meat, by going outside and stuffing eviscerated fowl with snow; he became quite chilled and developed fatal pneumonia. (a close second, in favorite historical tidbits, is that his mother Anne's maiden name was Cooke... in marrying Sir Nicholas Bacon, she thus became....)

I respectfully suggest not, sir. You use the word as everyone else does. Your intuitions just need to be "teased" a little. Two pages ago I said this: QUOTE Well, guys, on your account--that knowledge doesn't imply truth--we should be able to say the following: "It was once known that the Earth is flat. It is now known that the Earth is (roughly) spherical. The Earth has been known to be both flat and spherical." Now, no one has dibs on how the English language has to be used. Speak any way you like. All is I can say is: if you'd be willing to give a lecture to 100 knowledge thirsty students and say that (above), your cajones are bigger than mine. UNQUOTE Would you feel comfortable saying something like that? Radical skepticism of the Cartesian demon or the brain in a vat type always lurks in the background. I'm not sure it can be refuted. That said, it's not a position that is taken seriously these days -- even by philosophers. (Though you can always count on one or two exceptions) Edit: You might say we all work on the assumption that we are not brains in vats or victims of a Cartesian demon or puppets in the Matrix. It causes me no sleepless nights. How about you?

OK...this is Don Lincoln here. My name was invoked and a little bird came and suggested I pop in. I have not read all of the chat above. Regarding gravity and belief. First, belief is a non-scientific word....or at least it has lots of really ridiculous connotations. When a scientist says that they believe in a theory, they're just being sloppy. (And I include me in that. But language is language and we do the best we can.) "Belief" to a scientist simply means in this context, that the theory is consistent with all relevant known data and we can take it as an approximation of the truth. Now, on gravity. It's very clear that Einstein's formulation is more accurate than Newton's or, for that matter, any other suggested theory of gravity. It's also eminently clear that general relativity fails at small sizes and very high gravitational fields. For that, we will need a theory of quantum gravity. Some ideas have been put forward, but none have been validated in any way, meaning to all intents and purposes, we have no believable theory of quantum gravity. However, given the established validity of general relativity, it follows that that when quantum gravity is evaluated for gravitational fields not strong enough to manifest their quantum behavior, that the predictions will be effectively identical to general relativity. From that, we can infer that the bending of spacetime will be valid in quantum formulations as well, although there may be additional explanatory insights. Accordingly, I feel quite comfortable in saying that I believe in general relativity in the realm in which it is applicable. Similarly, I believe in Newtonian gravity in the realm in which it is applicable. After all, we shot the New Horizon probe to Pluto - traveling billions of miles, passing by several planets, and NASA hit a target 10 km in size. Newton works. Einstein works. Well, until they don't. That's all of science. Theories work as long as they work. One other piddly point. Our current understanding of gravity is qualitatively different from the other known forces. Sure. Some of you have been discussing the meaning of the word force. Classically, it means something that has the potential to cause an object's velocity to change according to some reference frame. At the quantum level, it has a somewhat different meaning. There it means that the phenomenon can effect some sort of change, be it changing velocity or causing particle decay. The fact that the word has a nuanced meaning depending on the size scale at which it is being evaluated implies that the word is fuzzy and anybody trying to nail it down, will fail. This brings up a more important point is that the mapping of words onto scientific concepts is a dangerous endeavor. It is highly unlikely that any word can be mapped into a concept so well that it is impossible to find an exception. There will aways likely be a qualification of some sort. Accordingly, don't hold onto words very hard. They will fail you. Instead, understand the more nuanced scientific principle for which the word is nothing more than an imperfect and ultimately inaccurate placeholder. For the person who complained about the videos being at a commercial site. Well, I've worked for over three decades learning this stuff. I spent half a year writing the lectures, which comprise 12 hours of clearly-explained advanced science. I spent a week filming the project and many hours ensuring that the quality of the video and audio product was high. And someone has the temerity to suggest that I and the production company shouldn't be compensated for that effort? It's like whining that someone won't come and paint your house. Go ahead - enroll in the streaming service - you will have access to an astonishing amount of knowledge and expertise, translated in such a way that non-experts can understand a portion of the more complex ideas. BTW I was a solid presence at SPCF for a long time, but I will not be a regular here. I have just contracted my 5th or 6th book and that will take enough time that active involvement here is simply not in the cards. Cheers....

If it requires significant speed to be useful, C is the obvious choice. C is also, in my experience, rather painful to use. If you want something relatively simple that can do the modeling (just not as quickly), try Python. It's fairly simple to learn and you can probably find pre-existing Python code that'll help you do what you want. O'Reilly's Learning Python is a good place to start.

Bullshit. This idea of "valid" is ridiculous as it has little application to reality and none to truth. I suspect you would like to idealize reality and turn it into a model that fits your rules. (Plato is not the only one who has that problem.) The Plague is a highly contagious deadly disease -- truth. Some people when exposed to the Plague do not get it and/or do not die -- truth. Does that negate the Plague as a highly contagious deadly disease? Men grow beards -- truth. If a woman grows a beard does that invalidate her as a woman? I have no idea where your thoughts of "absolute" and counterexamples come from, but they are idealized nonsense. It is not good Philosophy and it is not good Science. It is piss poor communication, so I will apologize for my part in that very bad communication. So what you are saying is that a premise does not need to be true; it can be false as long as it works and does what we require of it. Philosophy is not therefore necessary. Congratulations studiot. Religion will be so happy, because I think you just validated "God". Gee

I'd personally amend that, sir, to "how a lot of physicists view their work". It (i.e. antirealism) does appear to be the dominant poistion in physics. I doubt very much it is in other branches of science. Copied from page 2 . . . And I'd reiterate, this is almost certainly a minority view in science as a whole (physics being the apparent exception). Try asking a psychologist if he thinks consciousness is real. Try asking a geologist if she thinks tectonic plates are real. Try asking a paleontologist if he thinks dinosaurs are real. Try asking a chemist if she thinks oxygen is real. Try asking a neuroscientist if she thinks neurons are real. Try asking Richard Dawkins whether he thinks natural selection is real or merely a theoretical postulate, useful for predictive purposes, but not to be taken at face value. . . . Does physics try to describe the trajectory of cannonballs and other such thingies or not? If it does, then contra your own (seemingly crazy) view, physics is trying to describe reality (at least the observable part thereof).

Would "Does physics (try to) describe reality?" be considered more of a scientific question or a philosophical question? Is this question amenable to employment of "the scientific method"? Apparently not. Is there any experiment we might perform to shed some light on the question? Apparently not. It would appear, then, that the question is more philosophical in nature than scientific. So, with regard to your comment above, as thanks for offering my philosophical "take", among other slings and arrows of outrageous fortune, I got accused of being obtuse, suffering from comprehension issues, various other insults sprinkled liberally throughout the thread (to which, some of you may have noticed, I invariably turned the other cheek), a downvote or two, and a rap on the knuckles from a moderator. Ponder that while I ponder the limits of hypocrisy here.

Beecee, I can't believe that you actually wrote the above. I know that you have a serious bias against religion, and it became clear to me, while reading the other thread about science and philosophy, that you can not tell the difference between religion and philosophy. But how could you not know that your statements are almost the same thing that religion would believe? Read the following where I changed just two words: A religious theory or model, is not necessarilly after or searching for truth and/or reality. It is a useful, faith supported theory based on current evidence, that describes a certain situation. The thinking in your statement is exactly like the thinking that religion uses to promote the "God" idea. It is the same kind of thinking that validated drowning "witches", because it solved the problem of witches and made everyone else feel satisfied and self-righteous. No truth was required, no examining of the premises, no philosophy -- it just had to work. Well, Beecee, logic does not change by subject matter, so what is good for science is also good for religion, which would be why I stated that Studio's logic validated "God". Yes, I have seen this video many times and even used his examples to help me explain some aspects of consciousness. Feynman was brilliant, but had a bad attitude toward philosophy, which is kind of funny because he was very much a philosopher. Did you know that he took at least one philosophy class when he was young? He took his brilliant mind to an academic philosophy class which turned him totally against philosophy. He never got over it. I can understand his attitude because my first philosophy class gave me a similar disregard for academic philosophy, although I believe there are some classes that are worthwhile and taught well. I don't believe this for a minute. It looks like you cherry picked, adlibbed and generally corrupted what Wiki had to say. Considering the bias that I have read in your posts, this is not surprising. You can't tell the difference between religion and philosophy and talked about "absolute truth" with regard to philosophy, so I know you are clueless on this subject. Truth is subjective and is not "absolute" -- that would be either religion or maybe idealism. Gee Studiot; Because you asked me to explain what I see as the differences between truth and facts and how that relates to this topic, I wrote the following: I have spent the last week, or so, trying to verbalize how I see the difference between philosophy and science; it has not been easy. I think that a lot of the miscommunications and misunderstandings between us have been caused by very different ideas of what science and philosophy do, so I thought it would be helpful to clarify. My thoughts are that most people in science forums divide philosophy and science by the physical and the non-physical; the physical (real) being science and the non-physical (imaginings, ideas, ethics, etc.) being philosophy. Or they divide them by subject matter, such as ethics is obviously philosophy and mathematics is obviously science. Is some of this familiar to you? I think that Russell's explanation is a lot better and more accurate; science is what we do know; philosophy is what we don't know. Why is that? I am sure that some people believe that science knows what it is doing because it is superior or advanced, and philosophy does not know because it is inferior or confused -- this is nonsense. Earlier I stated that philosophy studies truth and science studies facts -- this is the biggest reason for the differences between these disciplines. Truth is subjective; facts are objective -- so truth (philosophy) is at the beginning of the process (where the observation, idea, or experience starts) and fact (science) is at the end (after confirmation or collaboration). Because truth is subjective, it can change because of perspective, time, and/or circumstance -- so truth can almost always be countered. It is rare to find a truth that is also objective, which makes it damned difficult to know anything for certain or come to any consensus in our conclusions. Hence, philosophy is what we don't know -- yet. So how can we know facts? Well, philosophy took the liberty of "establishing" certain truths to make them easier to deal with, so technically these truths are made-up. We took a one-to-one association of objects and ideas and called it counting, then we created numbers and then math, which allowed us to do all kinds of calculating. We established measures of liquid, distance, weight, volume, etc., and used numbers to measure many things. We broke down time into increments that allowed us a detailed measure of time. We established directional words like north and south, inside and outside, left and right, up and down, etc. With these objective truths that we actually created, or established, we could finally have a solid foundation for science and learn things that can be known. Hence, science is what we know. So it looks like science is an advancement of philosophy, and maybe does not need philosophy any more. Many people think this, but the problem here is that facts do NOT necessarily give us truth. For example: There was a hundred dollar bill in my hand that transferred to your hand -- that is the fact of what happened. So what happened? Did I give you money? Did we complete a contract? Did you steal it from me? What is the truth? Facts require interpretation and seldom, if ever, stand alone. Since science has become the "answer man" and philosophy has pretty much been removed from consideration, we are starting to learn just how dependent facts are on philosophy and truth. Just watch the evening news or see an advertisement; you will be inundated with facts, but will you see any truth? Facts are easy to manipulate because they do not stand alone and do not give us truth. These are some of the reasons why I think that philosophy and science are necessary to each other and interdependent. Although I can see why people think that philosophy is the beginning or base that started the process, but is no longer necessary, that is rather short sighted. Every new discovery is another beginning, every improved understanding is another beginning, every question that is answered prompts two or three new questions, which are two or three new beginnings. The only way that philosophy will ever become obsolete is when there is no new knowledge, no new discoveries, no new beginnings. By the way, it is not necessary to be a scientist in order to experiment and it is not necessary to be a philosopher in order to experience -- both disciplines use both methods. Facts can and do expose us to new truths and truths can and do uncover new facts. Gee