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Talk:Physics

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Hawking quote[edit]

Either I don't get it or it's a reference to God. So what is it doing here? Tetronian you're clueless 03:40, 4 December 2009 (UTC)

I think it's more of a question than an assertion, and gods aren't the only "answers". ħumanUser talk:Human 04:42, 4 December 2009 (UTC)
Yeah I guess that makes sense. I found it a bit odd though. Tetronian you're clueless 13:09, 4 December 2009 (UTC)
I could find a better quote. Nerd (talk) 01:09, 22 June 2016 (UTC)

Theory of Everything.[edit]

The article says that "One of the more popular of today's physics topics is the attempt to unify the theory of general relativity with quantum mechanics. This would be called a 'theory of everything' because it would mean that all four of the known fundamental forces (gravity, weak-nuclear, strong-nuclear and electromagnetic) are explained by one theory governing their interaction with the world as we know it." This isn't true. Loop Quantum Gravity, for example, is a quantum theory of gravity but it says nothing about unification of gravity with the other forces. Andy Frankinson (talk) 13:46, 28 June 2012 (UTC)

Just go ahead and change that to something more suitable. Scarlet A.pngtheist 13:48, 28 June 2012 (UTC)
Thanks! Does it look good now? Andy Frankinson (talk) 14:12, 28 June 2012 (UTC)

Four principal breakthroughs[edit]

I don't see why "planetary motion, fluid flow, wave propagation and the classical kinetic theory of gases" is all bundled into one. Sure, newton worked on most of them (not sure about the last one), but they are separate fields.

Four principal breakthroughs[edit]

I don't see why "planetary motion, fluid flow, wave propagation and the classical kinetic theory of gases" is all bundled into one. Sure, Newton worked on most of them (not sure about the last one), but they are separate fields. Super Dude,Where's my car? 13:57, 11 March 2015 (UTC)

  • Newton did manage to derive Boyle's law, which states that the pressure and volume of a gas (in thermodynamic equilibrium) are inversely proportional to one another. However, he did so by assuming that a gas may be modeled by a static lattice of atoms (yes, he did believe in the reality of atoms) that repelled one another by a force that weakens with distance, rather than a collection of randomly moving particles colliding with each other and with the walls of the container. It was Daniel Bernoulli who first derived Boyle's law in the latter manner. Finally, "planetary motion, fluid flow, wave propagation" are not separate fields; rather they are all parts of what we now call classical mechanics. Euler's equations of fluid flow and the Navier-Stokes equations are really just applications of Newton's second law, as is d'Alembert's (partial differential) wave equation. In fact, it was Newton who first showed that the speed of wave propagating on a string with two fixed ends depends on the tension along the string and the mass density of the string. I hope that is clear. Please do not hesitate to ask further questions. Nerd

Just for fun about matrices[edit]

Heisenberg came up with a formulation which he was uncertain what to do about. Matrix analysis was then an arcane branch of mathematics, but Max Born happened to have taken a course in that field and immediately realized the connection. Thus Heisenberg's matrix approach was born. Everyone was relieved when it turned out that the Heisenberg-Born formulation was equivalent to Schrödinger's wave function analysis. Cheerio Sorte Slyngel (talk) 22:51, 5 September 2015 (UTC)

  • A very good point. In fact, physicists unfamiliar with matrices, which is to say most of those working in the 1920s, referred to these objects as 'Heisenberg arrays' which obey 'Heisenberg's law of multiplication'. Nerd.
Just for added fun, when I took numerical analysis many a moon ago, it was estimated that at least 75% of all calculations in physics would entail the solution of massive systems of linear equations. To satisfy my ritræpa (that's the scientific name, it is commonly known as writing compulsion) I'll add that I don't think any discussion about these matters should omit mentioning Courant-Hilbert - mostly Courant. He gathered what he could about what was expressed in the name of the books, Methods of Mathematical Physics, that is all he could imagine what could be of use. This was before the quantum revolution and the physicists discovered to their delight, that someone had been considerate enough to give them what they needed - in advance. :-) Cheers Sorte Slyngel (talk) 00:31, 6 September 2015 (UTC)
Another good point. I plan to add a discussion on the relations between mathematics and physics soon. Nerd (talk) 16:06, 9 July 2016 (UTC)

Any good books debunking so-called 'fairy tale physics'?[edit]

I'm no physicist myself, so I'd much appreciate some input from people who know better than me what they're talking about when it comes to physics.

Looking around — taking care to avoid obvious crank tomes on the subject — I've tallied up the following books under the rubric of "Interesting":

I'm no stranger to (purportedly) skeptical books, expounding on the limits of our understanding (actually, that's really what I read the most about). Continuing that, I now want to expand on my skeptical understanding in the direction of string theory as well.

As such: If anyone has any advice/warnings/recommendations/caveats/abrasive rants to lend me about any/all of the above titles (and indeed about the larger issue of "Is string theory pseudosciece?"), I'd much appreciate to hear it. Thanks! Reverend Black Percy (talk) 15:00, 8 August 2017 (UTC)

I think I had some trouble pinging people before. As such, here goes: @Nerd @JorisEnter @Roo @Onychoprion @RoninMacbeth Reverend Black Percy (talk) 13:04, 10 August 2017 (UTC)
I don't know. I'll ask around my more hard-sciences-oriented friends, but I got nothing.RoninMacbeth (talk) 14:39, 10 August 2017 (UTC)
I don't know, either, sorry. Physics isn't my strong-suit; I know just about enough to be able to look up simple Relativity equations online. String Theory is well over my head. As is most any other model that's supposed to link gravity with the other forces. -- Onychoprion (talk) 15:48, 10 August 2017 (UTC)
I must confess I have not read any of those books myself. However, I do have a few comments to make on string theory. Perhaps a good -- indeed, great, in my humble opinion -- book on the subject is The Elegant Universe by Brian Greene, presenting an even-handed, if enthusiastic at times, take on the subject. Greene is a life-long practitioner of string theory with multiple discoveries. As it currently stands, string theory remains under construction, so it is simply unreasonable to characterize it as pseudoscience, at least not yet. Perhaps this should clear things up. You may have studied algebra or calculus-based general physics at school. In these courses, you have barely scratched the surface of the subject. If you major or even minor in physics, you will learn a lot more. One the subject of interest for our discussion here is classical electrodynamics, where you will find yourself often performing rather long calculations, especially when you get to problems involving electromagnetic waves or relativistic collisions. Undergraduate quantum mechanics is not necessarily hard mathematically, but is definitely so conceptually. In graduate school, you will learn (relativistic) quantum field theory, which is widely regarded as a difficult subject, certainly more so than classical electrodynamics. Depending on where you go to school, you may have an opportunity to take general relativity as well, and it is not easy either. String theory is even more complicated than either quantum field theory or general relativity. We should therefore be not too demanding in our expectations of physicists being able to understand its structure and to extract empirically testable predictions.
Personally, I find it surprising that some physicists stumbled upon string theory back in 1968, right in the middle of the Golden Age of General Relativity (~1965-~1974), and when the development of quantum chromodynamics (describing the strong nuclear force) and the unification of the electromagnetic and weak nuclear forces were well under way. No wonder why most physicists did not take it seriously. But now, the Standard Model of particle physics has basically completed and high-energy theorists are seeing progress slow to a crawl. (As for general relativity, it remains a fruitful topic of research, not least because we have finally directly detected gravitational waves, which opened up a brand new branch of science, namely gravitational-wave astronomy.) Meanwhile, string theorists continue to make progress. No wonder why some physicists are excited.
Finally, if you are concerned about the "end" of physics, here are some possibilities. First, reality may be similar to an onion. Our continued research peels one layer off only to reveal another. Perhaps there will be an end to this. Perhaps there never will be. Physics will "end" when we are no longer able or willing to dig deeper. This possibility was pointed out by Richard Feynman (who was not happy to see certain members of the general public demanding updates about the unification of this theory with that theory rather than asking about what we already know well). Second, there may be no unified description of the laws of physics whatsoever and we are deluding ourselves. (Note that this is similar, but not the same as the first possibility.) I find this hard to believe as the Universe is incredibly well behaved and that we have made tremendous progress in understanding how it works, especially in the last four centuries or so. Third, there is a final theory of physics, a central station to which all trains of explanation converge, which may or may not be string theory. But the completion of this theory does not mean physicists will have nothing left to do. They could continue to play around with the equations and extract solutions and predictions. They could work out how to better understand and teach it. Take general relativity as an analogy. Its publication in 1916 is by no means the final word on classical gravitational physics. Far from it, it was a new beginning, as physicists around the world probed the richness of this wonderful framework, publishing research papers and writing textbooks. They continue to do so till this very day. In his book titled Dream of The Final Theory, Steven Weinberg warned against naive reductionism. Just because the fundamental description of the Universe has been found does not necessarily mean other subjects are affected in any major way. Mycologists, for example, could continue merrily with their work. Brian Greene made the same point using geography as an analogy. Just because every part of the globe has been mapped does not mean an excursion here or there are without merit.
Sorry for the long answer. I hope you find it helpful. Let me know if you have any questions and I will try my best to answer them. Nerd271 (talk) 00:21, 11 August 2017 (UTC)
In general, I advise you to stick to books written by actual physicists. They may not be able to explain things well, but at the very least, you know they know what they are talking about. Mere science journalists or science writers are of very variable quality. Nerd271 (talk) 00:23, 11 August 2017 (UTC)
@Nerd Thank you for your input! I will certainly take it to heart.
Note that the two first books listed ARE written by actual theoretical physicists, however (and none of the four men are cranks).
As an example of the reasoning that made me pursue this avenue of investigation, please read this interview of the 2nd book's author (by the author of the 4th book).
What are your thoughts on it? I have to say Woit makes a lot of sense to me. All the best, Reverend Black Percy (talk) 09:25, 11 August 2017 (UTC)
Just going to note that this was an interesting read as well. All the best, Reverend Black Percy (talk) 09:48, 11 August 2017 (UTC)
Thank you for sharing. I must say I am getting a little wary of those who viciously attack string theory, which, remember, remains under construction. This is akin to scolding a toddler for being not as successful as some adults, many of whom actually have trouble learning new things, unlike this child, who is making progress as we speak. More simply, this kind of criticism is similar to those who think we should stop construction of a new building for no other reason than that it is not functional. Patience is a virtue. Also, the multiverse hypothesis gets a lot of flak from these critics for being not falsifiable. I beg to differ.
I forgot about this interesting article on the "second life of string theory". Whether or not string theory proves to be the next big major benchmark in modern theoretical physics, parts of it will almost certainly remain. Nerd271 (talk) 00:15, 12 August 2017 (UTC)

So far, so derp[edit]

Farewell to Reality: How Modern Physics Has Betrayed the Search for Scientific Truth was available in audiobook format, so I bought it right away. As far as the introduction went, I was with the author (who is a scientist) completely. But just as he began to get the steam up in his first chapter, I couldn't help but get slightly totally derailed by how messily he was handling the philosophical aspects of his argument.

As someone clearly more well versed in philosophy than the author, it concerned me to think "Ok, if he handles stuff I do know about this sloppily, how will he handle the stuff I need him to instruct me on?". (Then again; any author who scares the blinders off of my skepticism is doing me a favor, I suppose... But still!)

Sure, his philosophical examples are not even central to his overall point (which I agree with), but — as someone who, while not a physicist, essentially 'majors' in philosophy — it pisses me of that he had to misappropriate (read: misunderstand) Plato's allegory of the caveWikipedia's W.svg in order to make his point. In fact, it's by stopping halfway through Plato's basic story that he can 'make the allegory fit'.

The author then skips directly from Plato to quoting bishop Berkeley (of all people, for a book supposedly on physics) completely out of context, as if Berkley's words were somehow authorative (or even insightful), and as if Berkeley and Plato were discussing the very same things in their respective allegory and motto (protip: they really weren't).

The author also continually uses the expression "the thing in itselfWikipedia's W.svg" without even notifying the reader that this expression communicates an implicit acceptance of Kantian metaphysics. The author also phrases himself so sweepingly that he makes it sound like Plato was reasoning in Kantian terms.

To top things off, he then skips directly to cite (as a philosopher) the Templeton Foundation quantum woo-meister laureate Bernard d’EspagnatWikipedia's W.svg on his concept of so-called 'veiled reality' — which would be defensible, if done in strict conceptual isolation (e.g., as a proverbial stand-in for the arguable implications of Bell's theoremWikipedia's W.svg).

But no: he keeps the specifics underlying his inclusion of d’Espagnat both broad and vague — which is kind of a problem, considering d’Espagnat actually qualifies among those very same 'fairy tale physicists' the book supposedly sets out to debunk. Facepalm.png

What's worse is; I totally get what the author was trying to say. And I totally agree with him on that, because that point is reasonable. But he didn't actually have to resort to using faulty thought examples, borrowed lingo and the namedropping of dusty old thinkers to make said point. But alas...

Philosophy rant over. I'll try to keep listening now. Reverend Black Percy (talk) 17:34, 8 August 2017 (UTC)

@Reverend Black Percy: Most physicists I have encountered tend to avoid dipping their toes into philosophy, and wisely so. In fact, some take a devil-may-care attitude towards the philosophical implications of the subjects under discussion. If you are trying to understand how nature works, then nature is always right. It makes no sense to impose your preconceptions upon nature. The only thing that really matters in science is that your hypothesis or theory produces predictions that agree well with experiments and observations. Whether or not a hypothesis or theory is somehow philosophically objectionable is irrelevant. Nature is under no obligations to conform to your expectations. I hope you don't take this the wrong way. But I have seen way too many low-grade philosophers attempting to criticize physics who in reality are showcasing their ignorance. But the reverse can also be true, when physicists step outside of their domain of expertise. Some cannot resist the temptation to make things sound more impressive or profound than they actually are. (Richard Feynman was merciless in questioning such individuals when they give lectures or seminars.) Nerd271 (talk) 21:05, 14 August 2017 (UTC)