Thought Experiments

18
Jun

The Mistaken Assumptions That Changed Physics History

“Don’t assume,” they always say.

Last month, Avi Loeb, an astrophysicist at Harvard, published an essay on how mistaken assumptions have delayed the progress of astronomy. In the same spirit, I wanted to find out how the course of physics has been influenced by assumptions, acknowledged or otherwise. Can lessons from the past help us be more aware of the assumptions we bring to physics today? Is it desirable—or even possible—to work without assumptions?

In the years after scientists came to accept light as a wave, brilliant researchers spent untold hours chasing after the “ether,” hypothetical stuff through which light waves were thought to propagate. Water waves are disturbances in water, sound waves are disturbances in air, and so light waves must be a disturbance in something, the reasoning went. When the sophisticated experiments built to search for the ether couldn’t find it, theorists got to work trying to explain away ether’s experimental no-show. It was only when Einstein published his theory of special relativity in 1905 that the solution became clear: Ether wasn’t just hard to find. It didn’t exist.

If Einstein resolved one roadblock, he set up another. He adamantly refused to accept the randomness built in to quantum mechanics, famously quipping that God doesn’t play dice with the universe, and holding fast even as experiment after experiment (including one he helped to design) showed those dice tumbling. “My instinct for physics bristles at this,” wrote Einstein.

dice_620
Dice or no dice? Credit: Yannis/Flickr, adapted under a Creative Commons license.

It’s hard to imagine an astronomer dismissing observational data on the evidence of her “instinct for astronomy,” which highlights a key difference between the two fields. “The special aspect of astronomy is that we have limited information on things far away; it’s not like experiments in the laboratory where we can control conditions,” says Loeb. Astronomers therefore have to make more judgment calls than their colleagues in physics, and when they get it wrong, it’s usually because they don’t recognize the limits of their knowledge—their mistakes are failures of humility.

Physicists, on the other hand, have heaps of data, but they approach that data with certain assumptions that feel like common sense: Waves need something to wave through! The universe should behave predictably! But, says David Kaiser, a physicist and historian of science at MIT, “Sticking to what feels like common sense or intuition can trip us up.”

Einstein was “one of the most accomplished scientists ever—he took part in the process of discovering quantum mechanics,” says Loeb, and yet “he had a prejudice that turned out to be wrong.”

To Loeb, the ideal scientific attitude is like that of the perfect detective, who brings no assumptions about the guilt or innocence of any individual to his analysis of a case. “What you want is to start with a completely blank slate,” says Loeb.

But Kaiser takes a rosier view of scientific mistakes, one that suggests a somewhat different corrective. “I think we can find instances where mistakes led to productive outcomes,” says Kaiser. “It’s not always all bad.”

Indeed, Kaiser points out, even though physicists were wrong about the ether, their investigations led to critical insights, like Maxwell’s equations, which are now part of the essential physics toolkit. “We still use Maxwell’s equations even though for Maxwell, there was no such thing as an elementary electric charge. He thought the world was made out of ether!” The equations stayed the same; the world changed around them.

Hidden assumptions can also live at the heart of how we do science. Today, for example, most theorists expect that the deepest laws of nature will turn out to be simple and elegant. So far, that assumption has held up pretty well. But, says Kaiser, it’s possible that today’s most vexing puzzles—dark matter, dark energy, the nature of black holes—signal some breakdown of our basic assumptions about elegance and simplicity.

While hindsight might lead us to brand assumptions as bald mistakes, to Kaiser, they’re more like misplaced priorities. In his 2011 book “How the Hippies Saved Physics,” he tells the story of quantum physics’ journey from the “shut up and calculate” mode, which dominated teaching and research in the years after World War II, to a more open-minded approach that embraced “late-night speculation.” What the Cold War pragmatists never guessed was that the philosophical musings of the “hippies” would yield up a raft of cutting-edge applications based on the strange phenomenon of entanglement.

“Coming out of World War II and during the war, physicists were extremely creative under tremendous time pressure,” says Kaiser. “These were extremely practical, goal-oriented applications of the Schrödinger equation. They were absolutely brilliant with world-changing impacts,” including everything from transistors to nuclear weapons. Yet a cultural resistance to “daydreaming” kept them from thinking deeply about the meaning of the equations they employed so successfully.

“We are not going to get to a land where we have no biases and no intuition,” says Kaiser. Scientists are human beings; their neutrality comes from the rigor of their methods rather than some superhuman ability to transcend personal biases. So, he argues, we should build “safety nets” into the scientific culture to “allow little pockets of support for crazy ideas”—that is, ideas that defy common sense and conventional wisdom and yet have some kernel of plausibility. Kaiser is optimistic that today’s scientific culture is making room for “weird” ideas, with microgrants and new research centers, like the Perimeter Institute, where “not-quite-mainstream stuff” can gain some purchase.

One day, those offbeat ideas just might start to seem like common sense.

Go Deeper
Editor’s picks for further reading

FQXi: Which of our basic physical assumptions are wrong?
Read the winning entries in FQXi’s 2012 essay competition.

Hyperphysics: The Michelson-Morley Experiment
Learn about the 1887 experiment that helped put ether theory to rest.

Wikipedia: Bohr-Einstein debates
Explore the twists and turns of the ongoing dispute between Albert Einstein and Niels Bohr over the foundations of quantum mechanics.

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Kate Becker

    In a parallel universe, Kate Becker is senior researcher for NOVA and NOVA scienceNOW and a blogger for Inside NOVA. In this universe, she is your host here at The Nature of Reality, and it is her mission to blow your mind with physics. Kate studied physics at Oberlin College and astronomy at Cornell University. You can also follow her on Twitter and Facebook.

    • abc123

      Sadly I heard a contrary story on NPR recently. In it a physicist was interviewed who described the academic physics world as bleak…more people jockeying for less funding for even “safe” (I.e. mainstream) research.

      When your work, by definition, plays at the edge of the schoolyard where traditional concepts and common sense break down and are then reimagined, the dialectic process inherently must move between equally strong poles of imagination and experimentation. Without the former, experimentation is done for its own sake and results in little innovation.

      I believe Einstein’s reluctance to accept uncertainty as part of nature was natural for his time for it was the beginning of the end of logical positivism…the optimism born of the rapid advances in science and philosophy of the Enlightenment that I’m sure appeared to assure the smartest among us that we would soon have this atomistic, monistic universe figured out. To have gained so much only to learn that uncertainty was an inherent part of nature must have felt like a collective slap in the face to those who toiled so hard to rebirth humanity from the dark ages and escape Plato’s cave on solid footing.

      I often think of Wittgenstein: paid to live alone, far from civilization, to think and write…and what a return on investment that was. Sadly I think those days are lost.

      Bottom line is we gotta gave both, at least equally as strong, in order to move forward.

    • jimg

      I can’t believe nobody mentioned Einstein’s cosmological constant, which he described as the biggest blunder of his career, but seems to match the density of the universe perfectly.

      • katembecker

        Good point; wait a while and a “mistake” may start to look like an insight!

      • Zaoldyeck

        “I can’t believe nobody mentioned Einstein’s cosmological constant, which
        he described as the biggest blunder of his career, but seems to match
        the density of the universe perfectly.”

        … Because it didn’t. Einstein used Λ in order to force the universe into a steady state, it had an opposite sign, while the energy density of ‘dark energy’, is causing the expansion of the universe.

        Also the magnitude of the observed cosmological constant is rather impossibly small, certainly nothing that ANYONE actually predicted, or would have predicted. Our smallest predictions of what lambda could be were over a hundred orders of magnitude too big.

        Nima Aranki-Hamed has some excellent lectures online regarding this problem and various proposed solutions among the theoretical physics community. Most of it goes well over my head but they’re interesting puzzles with interesting implications.

    • SERAPH1212

      Complete and utter arrogance.

    • Steve Barnhaus

      This author suggests that Einstein rejected the notion of space as something distinct from nothingness. That is utterly wrong. He simply argued that it could not comprise any known form of matter– that it was not a gas like true ether is. But he most definitely built his theories around the concept that it was analogous to a gas; hell, he even used the word ‘ether’ in his writings: “Recapitulating, we may say that according to the general theory of relativity, space is endowed with physical qualities; in this sense, therefore, there exists an ether. According to the general theory of relativity, space without ether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring-rods and clocks), nor therefore any space-time intervals in the physical sense.”

    • D.C. ADAMS

      The New Standard Model – http://www.amazon.com/New-Standard-Model-Introduction-Dimensional-ebook/dp/B00JXW7KGI/ref=sr_1_1?ie=UTF8&qid=1403275312&sr=8-1&keywords=the+new+standard+model

      Everyone quotes Einstein, but they rarely understand him. He was looking for a better interpretation of mathematical laws as they relate to the explanation of our physical world. Experiments like the Higgs will be proven incorrect next year in 2016. The point of physics is to continuously, gradually iterate and mitigate our understandings until we arrive at a precise undeniable conclusion!

      • Zaoldyeck

        ” Experiments like the Higgs will be proven incorrect next year in 2016.”

        What do you mean by this? Do you mean that the signal that both CMS and ATLAS detected at ~125GeV will vanish and we’ll lose our 5+ sigma result? Do you mean it will have spin? (Will it *gasp* be Spin 2?!)

        What do you mean by ‘it will be proven incorrect’?

        Edit: Or equally confusing, spin 3/2.

        • D.C. ADAMS

          E) All of the above! – Mark my words…the more we find out about it, the more we will find out (the particle and theory) does not fit our previous predictions. Unfortunately proponents will go to unimaginable extreme efforts to explain why it is incorrect when all we need to do is consider an alternative theory-something Einstein suggested prior to the development of Quantum Mechanics. – http://www.amazon.com/Tale-Two-Theories-Motivation-Dimensional-ebook/dp/B00KQUM2DM/ref=sr_1_5?ie=UTF8&qid=1403532364&sr=8-5&keywords=the+tale+of+two+theories

          • Zaoldyeck

            Is mount Everest, the tallest mountain in the world, located in Asia, Australia, or is it really just a small hill we mismeasured?

            Saying “all of the above” isn’t an answer, at least not without a LOT more explanation what you mean by that.

            I asked you a series of mutually exclusive questions, you can’t have a spin 0 particle that is also a spin 2 (like saying Everest is in both Asia and Australia at the same time) nor could it be EITHER spin 0 or spin 2 (or any other half integer) while having our five sigma signal vanishing (like saying Everest isn’t real at all)

            All of those questions imply different things about how you believe physics to operate. Expecting a signal to vanish verses expecting it to be real but different from what was expected imply very different models of physics.

            All of the above isn’t then any real answer to my question. You gave me no insight into how you believe the Higgs is flawed. Plus citing an amazon book rather than an arxiv link is poor taste. If it is your research I will read the Arxiv preprints, not some book designed to earn money by saying strange things.

            • William F. Nappi

              I wouldn’t be comfortable saying that the Higgs is either flawed or not flawed, but otherwise, I REALLY like what you’ve said here. It’s given me better insight to what I DO know and a little about what I didn’t know.

            • Zaoldyeck

              The more statistics that are done the more and more we’re convinced it is a zero spin particle, which means if it’s not “The Higgs”, it is Higgs-like enough to where even if branching ratios aren’t exactly like predicted (Which would be awesome, as far as I know the excess in the diphoton channel did vanish in 2013 but it’d be cool if it reappears) we’re pretty safe in calling it the Higgs.

              Very few people in the physics community seem to expect that to change, and I know some people on ATLAS who if they found the particle looking like it is something genuinely new or different, I’d have heard *SOMETHING*, even in passing. (That buzz even should happen on r/physics no less)

              So when it comes to people saying “The Higgs result will be proven wrong!” it is a statement that while we do need new physics, and physicists want SOME divergence from the standard model as a hint for new physics… most of the people who shout to me often have no idea what they actually mean by those statements. It makes it easy for a laymen to pretend and act like they have an education on the subject, without addressing the actual questions physicists have (and ask).

              As I said, most physicists don’t really question it’s a spin zero particle anymore. That’s why it’s usually an adequate litmus test for what someone really means when they talk about the Higgs. If they expect new physics to emerge from it, but at least admit basic empirical results… they probably have some sense of what they’re talking about. If you say “it’s wrong, in some totally random way I can neither describe, nor explain”… they’re probably talking out of their -ss about physics.

              Physicists don’t have all the answers, but they don’t usually answer questions like mine with “E) All of the above! – Mark my words…the more we find out about it, the more we will find out (the particle and theory) does not fit our previous predictions. Unfortunately proponents will go to unimaginable extreme efforts to explain why it is incorrect when all we need to do is consider an alternative theory-something Einstein suggested prior to the development of Quantum Mechanics.”

              My professors would never have given me such a weak answer to such a strongly defined question.

            • William F. Nappi

              You clearly went to better schools than I have. I’ve been more of a General Education kind of guy since I started my ongoing life time of learning-stuff adventure back in 1979; so I’ve gone to all junior colleges (except a writing class at UCLA).

              A few of the teachers, not one single professor have I had save for one with whom I was at odds over centripedal as opposed to centrifugal forces where as it turns out, they work in tandem really is what I’ve concluded based on the natures of the two… anyway, more than one, but especially one teacher, I really had to resist the temptation to NOT beat the guy up he was so incompetent…I think I’m rambling now…

              THE POINT IS, I think you clearly got the most out of your education however you chose to downplay what you DO know.

              I appreciate your input. Thanks.

              WFN

            • Zaoldyeck

              I went to a decent university with a surprisingly good physics department (I always was pleasantly amused when I found myself citing papers conducted at my school just because they happened to have the results I needed to cite)… so I at the very least am not too terribly removed from the larger physics community and I *try* to keep informed, even if I admit my math skills kinda suck.

              One of my favourite professors (who I got to work with a couple of times in labs and he’s awesome as can be) was on the WMAP project, I had another who handled quite a bit of the electronics management for ATLAS (And one of his doctoral students, randomly, turns out to now be dating my brother’s ex)

              Suffice to say, the physicists I got to know were not idiots, and I have profound respect for everyone in my university’s physics department.

              Oh, and with respect to centrifugal force, as is almost everything in science… there is a relevant xkcd.
              http://xkcd.com/123/

            • William F. Nappi

              1. xkcd is pretty funny. I just checked that out.

              2. With that then; does centrifugal force NOT oppose centripetal force which I suppose IS just an apparent force, which results from one or the other extremes of inertia, most likely a body IN motion, since it occurs during a turn.

              Not getting flippant with YOU, but IF NOT, then somebody better correct those aviators and their kind because they’re teaching and learning about the dynamics of flight all wrong.

              Finally, you mentioned your math skills. I’m not very good with functions myself outside of spreadsheet stuff.

              Math skills lacking I can see how it would be very difficult to be taken seriously by advance physicists if one cannot prove something mathematically.

              AND, oh yes. WITH the exception of the centripetal/centrifugal force(s) argument/disagreement, the good Dr. Midili was AWESOME. What a great, GREAT, (crazy s-o-b he was,) but nonetheless most excellent ehh, quasi-professor of the natural sciences.

              Without mathematical proof then, is anything hypothetically or theoretically based even otherwise ‘plausible’, to be considered some creative form of art instead?

            • Zaoldyeck

              1) There is a relevant xkcd for nearly any topic in science, but especially physics. So it kinda has a big ‘geek’ following.

              2) Centrifugal force IS centripetal acceleration, in a difference reference frame. That’s the point of the comic, in that if you write out your free body diagram from the perspective of the moving reference frame (the person on the centrifuge) you experience an outward force, the free body diagram has centrifugal force show up clear as day.

              BUT! If you then move to an inertial reference frame (that is, one not accelerating) then the acceleration is all inward, ‘centripetal acceleration’. The most important thing isn’t what we call it, but rather, that we are consistent within our setup.

              It’s *usually* easier to work from inertial reference frames, because outside of them, Newton’s Laws break down and that gets hard to work with. (This should be intuitively obvious. If an inertial reference frame is one that is ‘not accelerating’ then everything in it to accelerate needs to be acted upon by ‘a force’. But in an accelerating reference frame, in absence of forces, all objects are still accelerating!)

              How you set up the problem is a big important step, but so long as you’re consistent, you should always get the right answer, even if you’ve made life much more of a nightmare than it should be in doing the problem.

              Still I have no idea how aero engineers use those terms and since consistency is the key, they don’t need to map onto each other if the uses are sufficiently different in most circumstances. “Does centrifugal force actually exist”, like in the comic, mostly dies by the end of High School.

              “Math skills lacking I can see how it would be very difficult to be taken seriously by advance physicists if one cannot prove something mathematically.”

              It’s not about proving things mathematically, it’s about DESCRIBING things mathematically. Math is like a language, it is meant to convey information in a very strict and precise fashion. So without an intuitive understanding of what the math is describing, how functions map onto each other or how transformations work or how observables work, etc, etc, you aren’t really understanding anything, you are just saying words.

              The math is how we began to form our words, and the attempts to paint more intuitive descriptions have to usually come from the math, because the things being described are usually so alien in concept that the only thing both robust and adaptable enough to describe them is mathematics.

              The “proof” might convince others, but before you even get to the proof, if you don’t understand the math, you don’t understand the subject, and can’t really offer anything reasonable new or interesting simply because you haven’t gained the information the math is supposed to teach you.

              It’s more about the proof, it’s about the intuitive understanding. It’s about knowing what the operations you are doing mean, and how they relate to each other.

              That’s something that’s hard to come by without any formal education. Not impossible, but d-mn difficult.

            • William F. Nappi

              1. “Does centrifugal force actually exist”
              Not to be overly simplistic but I feel some steps must be taken back.
              Q. Is it *centrifugal force* or is it not an equal or opposing force of centripetal force?
              A. In the context of aviation terms and application, in strict compliance with Mr. Newton’s 3rd Law regarding action and reaction, NOT to be hung up in Newtonian Physics: Yeah. acceleration or even a steady rate of speed is being applied. One force opposes the other.

              (Sidebar; Newton’s third law applies to the bottom of a plane (read a wing(s) surface) where Bernoulli’s principle law applies to the top of the wing’s surface (it works, okay). If you don’t want to take my word for it that’s fine. I’ll notify the FAA at once to let them know they’re books are in need of updating if you can prove otherwise.

              I’m certain they’ll appreciate this new information because right now they’re under the impression that that’s how it works because that’s what the aerodynamic engineers keep telling them.

              It’s even in the FAA publication known as the PHAK Pilot’s Handbook of Aeronautical Knowledge. I have a copy. Took the class a few years ago for a Private Pilot’s Certification, blah, blah, blah) so much for centripetal anything dying after high school. The laws apply I did not cite an invalid reference.)

              In the context of the existence of centrifugal force NOT occurring, okay, I’ll take your well informed word for it PRESUMING that non Euclidean algebra is being used perhaps? (You do know Mr. Einstein arrived at many conclusions in his General Theory of Relativity using just plane geometry, yes, in that “gravity” is … okay it’s been awhile… please correct me if my memory is not 100% accurate at the moment, “gravity” is a geometric property of space and time. (???)

              As for mathematical models ‘explaining’ some concept as opposed to proving it, I appreciate your explanation. However, you are the one who said your math skills s^ck.

              I just said “I” have a rough time with functions. To me they aren’t easy problems to, uh, explain something physical, imaginary or otherwise.

              Finally, for now, just for the heck of it, I feel it bears worth mentioning that according to Mr. Newton’s 2nd Law in the form: F = ma fictitious (or among others “inertial”) forces ALWAYS are proportional to the mass acted upon.

              Granted you changed the frame of reference to one where acceleration is constant: why? Because of the non-inertial reference frame because there’s no physical interaction????

              Gravitational force is an inertial force according to GR.

              RIGHT now, MY wires are feeling a little crossed here. I’m lost somewhere in gravitational forces, free fall, zero acceleration unification of quantum and classical mechanics (something’s wrong here) and IT’S JUST BEEN A BAD DAY and I’m still getting over it.
              Sorry if this whole thing just got messy, I’m hitting the ‘Post as…’ thing on this….

            • Zaoldyeck

              “Q. Is it *centrifugal force* or is it not an equal or opposing force of centripetal force?”

              Huh? Depends entirely on how you want to define the word I suppose. Consider from the frame of bond on the giant centrifuge. What forces does he feel? Well, he feels a force pushing him down onto the ring, and the ring exerts an equal (but opposite) force keeping him from flying straight past the ring. So from his perspective, his acceleration towards the ‘floor’ could be called ‘centrifugal force’ and the normal force, that the ring exerts on his body, I suppose you could if you want call ‘centripetal force’, an equal opposing force to the ‘centrifugal’ force. As long as you’re consistent within your frame, who cares what you name stuff?

              I have only been exposed to ‘centrifugal force’ as a pseudo-force in circular motion, and since fluid dynamics is typically not circular motion (I am not even slightly equipped to deal with whatever goes on when a plane does a barrel roll) I don’t really care what context aero engineers want to use any of the terms. All that is important as far as math goes is you be consistent with what you mean. No books need to be ‘updated’ unless they are inconsistent within (or between) themselves.

              “In the context of the existence of centrifugal force NOT occurring,
              okay, I’ll take your well informed word for it PRESUMING that non
              Euclidean algebra is being used perhaps?”

              Huh? Non-educlidian geometry is being used for what? Why do we need to abandon Euclidean geometry?

              ” (You do know Mr. Einstein arrived at many conclusions in his General
              Theory of Relativity using just plane geometry, yes, in that “gravity”
              is … okay it’s been awhile… please correct me if my memory is not
              100% accurate at the moment, “gravity” is a geometric property of space
              and time. (???)”

              That gets into a lot of really weird and difficult issues. First, if by “plane geometry” you mean Euclidean, then that’s because Riemannian spaces can be made locally euclidian. (Ask me to prove this and I cannot, but it’s an accepted property if you want to look it up)

              So since Einstein needed to describe curved spaces in four dimensions, things like differential geometry were important. Differential geometry is hard. I have barely any exposure to it and what little exposure I do have is mostly me in the fetal position.

              “As for mathematical models ‘explaining’ some concept as opposed to
              proving it, I appreciate your explanation. However, you are the one who
              said your math skills s^ck.”

              And they do. If they didn’t, I’d have a better grasp of the words I just wrote down. But I don’t, I at best know what kinds of descriptions the math provides, but I haven’t done sufficient practice and effort to actually learn any of that. Hell, I barely know what a holomorphic function even is! And I had an entire semester where they were a fundamental concept! (For what it’s worth, Complex Analysis did give me my best insight into what the world of differential geometry is supposed to address. It is an incredible subject to expose undergraduates to and I’m thankful that it really isn’t *that* difficult.)

              Also a note for any graduate students passing by, who might make it sound like I’m boasting getting my terms confused. I have had exposure to holomorphic functions in complex analysis. I have NO idea what homology means, and just looking up the terms together and finding stuff like this frightens me.

              http://www.sciencedirect.com/science/article/pii/S0001870803002330

              …. Now I admit my standards for what I consider a ‘good math student’ are probably higher than most, but to anyone schooled in math, they’d likely share a definition which would likewise exclude me.

              “I just said “I” have a rough time with functions. To me they aren’t
              easy problems to, uh, explain something physical, imaginary or
              otherwise.”

              I don’t write out equations, but the thought crosses my mind every now and then that there’s a fun probability problem that most students have to confront of “the bus leaves at X+/-Y. It takes you Z minutes to walk to the bus stop. If you miss the bus, it takes you Q>Z minutes to arrive at your destination. How many minutes early should you leave to minimize your overall arrival time?”

              How I organize my mind has changed with increased math education. I see puzzles and problems in areas I never would think to before.

              Math gives structure, and it conveys information. That intuition takes time to build, I was lucky to have a good early math education, but higher order math still scares the living daylights out of me.

              “Finally, for now, just for the heck of it, I feel it bears worth
              mentioning that according to Mr. Newton’s 2nd Law in the form: F = ma
              fictitious (or among others “inertial”) forces ALWAYS are proportional
              to the mass acted upon.”

              Yes, umm, I suppose that’s true. But it’s also why it was amended to F=dp/dt, since momentum doesn’t necessarily scale simply with acceleration, thanks to relativistic terms. In general every day life, F=ma is well, well, WELL sufficient.

              “Granted you changed the frame of reference to one where acceleration is
              constant: why? Because of the non-inertial reference frame because
              there’s no physical interaction????”

              Huh? Sure, why not? You can define or impose an artificial reference frame that does just about anything, without assuming a ‘physical interaction’? Say you’re in a car accelerating on a highway, and want to look out your window. If you define yourself to be stationary (which you are fully allowed to do) then the rest of the world appears to be accelerating with nothing acting on any of the objects.

              It’s not very convenient then to do math from, however, when you treat everything as accelerating but you stationary. Much easier to treat you as accelerating and everything else stationary.

              “Gravitational force is an inertial force according to GR.”

              Since a body in ‘freefall’ in GR is not acted upon by any forces, but it doesn’t seem a particularly useful or intuitive way of thinking about skydiving, I prefer to think of gravity as a ‘real’ force, rather than the result of your particular geodesic. Whatever convention is most useful is generally the best to pick, so long as you’re consistent.

              “RIGHT now, MY wires are feeling a little crossed here. I’m lost
              somewhere in gravitational forces, free fall, zero acceleration
              unification of quantum and classical mechanics (something’s wrong here)
              and IT’S JUST BEEN A BAD DAY and I’m still getting over it.”

              Those are all subjects well beyond my math skills. I can describe to you what a geodesic is. How it came about. And not much beyond that.

              … My GR is pretty limited, my SR isn’t terrible however.

            • William F. Nappi

              I’m feeling a little overwhelmed. Thank you for the update on F=ma to F=dp / dt I was NOT aware of this, ya’ never know when it might be important to know this WELL WHAT DO YOU KNOW by the very virtue of this fact it’s importance has already manifested itself in the absence of some degree of ignorance on my part. (God I hate to be ignorant about something ALL THINGS BEING RELATIVE, well it is virtually and naturally impossible for anyone to be ‘ignorance free’ or they’d know everything about everything. T or F?

              OKAY. So, again I appreciate the update on what F is = to.

              As for centripetal and centrifugal forces, I’m not budging on my firmness in natural laws that they do not oppose each other any more than, say “gravity.”

              Does gravity push? Or does gravity pull? There must be some opposing force if it does one or the other, therefore it must do both, yes? (Please don’t say no. I’m bent on the notion that the FAA repeatedly uses the term “the ‘force’ of gravity in any publication I’ve read anyway not to exclude “The Airplane Flying Handbook,” a MUST, absolutely, positively MUST, make that a BETTER read for any airman… READS ‘FORCE of gravity as opposed to just one mention un the PHAK about the ‘pull of gravity” So in retrospect, hmmm. Personal dilemma. Case closed unless you care to elaborate or query anything on that.)

              Coincidentally, 1st, I could go on about airplanes and flight all day and night regarding The Wright Bros. WW I, aeronautical terminology (why there are so many French terms) etymologies ALL KINDS OF trivia BUT as it relates loosely to our correspondence: did you know that an aero planes wings are actually in fact ‘planes’? (As in geometric type “two-dimensional surfaces in or on which a straight line between any two points will lie
              wholly on that surface” essentially, type ‘plane?’

              Hence the term given air/aero ‘plane’.

              So gravity does it push, pull or do both? I persist given opposing forces MUST absolutely, POSITIVELY, no 2 ways about it be considered in a 3 -D world viewed I suppose FROM a 4th dimension. (Or not.)

              In closing, regardless of what you say about yourself, me? I think you would be an incredible high school teacher of the natural sciences, MAYBE even math. If you didn’t tell anyone your math skills weren’t 100% perfect, given a comment maybe something like, ‘If YOU see a mathematical inconsistency PLEASE enlighten us” or “tell me and I’ll look into it” whatever no one would notice the difference at your level.

              Anyone so inclined to advance would catch mistakes later maybe??? Or not.

              Nice meeting you. It’s been incredibly interesting. Tea time here believe it or not.

            • William F. Nappi

              ONE OTHER THING I found to be of interest, not that the overall communication wasn’t interesting to me, BUT you mentioned in closing that your GR understanding is limited (likewise AND/but I have been trying to get back around to reading more of it – the tab is open on another pc i another room)

              SR, I would debate points on events occurring simultaneously FROM or using a different point of reference. NOT in some attempt equivalent to, say, using the order of operations in a spreadsheet disregarding or omitting parenthesis or something and expecting to get a correct answer, YEAH, I would get an answer but not the one corresponding to the actual argument intended, NONETHELESS NOT trying to contradict SR because the bottom line on that theory has stood the test of time, more than could be said of Aristotelian “Physics” (unquote) or something but I AM curious about a few things just the same. Not that any conclusions invalid or otherwise might come of those conclusions…just curious.

              GR, yeah, I wanna get back to that: SR ok mc2 is the energy possessed by the mass BEFORE it absorbed the energy Eo (Section 15 ~[56] those are the general results I got from my notes; (I don’t know what happened but they jump from there to quarks, hadrons, baryons, mesons, pions,kaons, cosmic rays, visible light … go figure okay! What I CAN tell you about GR for what it’s worth to you, is this: GR generalizes SR AND Sir Isaac’s Law(s) of Universal Gravity where:

              SR generalizes Galileo’s Principal of Relativity.

              To sum this up in simplest terms then: GR describes SR (which describes Galilean Invariance/principal of relativity and Newton’s Law of Universal Gravitation and the three unified whatever it is that it unified and all the answers were correct leaving Messers. Galileo, Newton and Einstein in agreement but now this Quantum Mechanical question thing in need of unification with the Classical exists but you already knew a lot of this maybe and I think I’ll go get that tea now.

              (sigh) Cartesian Coordinates anyone?

            • William F. Nappi

              With the temperature of my tea decreasing at an alarming rate I cannot resist whipping the horse just at least one more time ‘cuz the thing won’t die. RE: Mr. Bond on the centrifuge.

              As you pointed out (“What forces does he feel?) Well, he feels a force pushing him down onto
              the ring, and the ring exerts an equal (but opposite) force keeping him
              from flying straight past the ring. So from his perspective, his
              acceleration towards the ‘floor’ could be called ‘centrifugal force’ and
              the normal force, that the ring exerts on his body…” STOP.

              Consider taking a bucket nearly half full of water. You pick the bucket up by it’s handle and twirl it windmill style. (Does the water spill out of the bucket in the 12:00 position?) It doesn’t because centrifugal force is PULLING the water to the bottom of the bucket.

              In the meantime, centripetal force is PUSHING the water to the bottom of the bucket.

              At this time, please take a moment to think about this, then answer honestly, and objectively without bias or prejudice to formerly held dogma and the like. T or F?

              (Sidebar: you asked ” What forces does he feel?” Uh, G-forces?)

              Okay. Lifeless horse given time to re-think it’s behavior while it’s still breathing. That’s all for me tonight/this morning, whatever.

            • William F. Nappi

              I hope I did not give you the impression that I presumed to understand everything you said. However as for spin 0 and spin 2 and no half integers, what this called to mind is a concept POSSIBLY in string theory, I’m not sure you MAY know what I’m talking about as I VAGUELY allude to sub-atomic particles that it is believed and I think possibly PROVEN that they can in fact be or exist in 2 different places at the same time.

              With that basic concept of thought in mind, PROVIDED you’re familiar with what I’m getting at, (it’s 2 a.m. I’m having a hard time recalling details right now) IF some ‘one’ particle is occupying 2 places only in different places far apart from each other…

              is their behavior identical? That is, for example would a Higgs with 0 spin be also of a co-existence elsewhere ALSO be spin 0? OR, could it be of some spin ‘anything’??? OR would it just be identical in nature, period?

              Any definite answer on this?

      • William F. Nappi

        Next year in 2016??? Today’s date, as I write is July 10, 2014. Is there some time lapse, collapse or spread of some type expected I’m deeply concerned to occur that we should know about?

        I’m deeply concerned here as I find this disturbing the way I wake up some days and ask myself, “What happened?” as it is.

    • Zaoldyeck

      I’m glad you/your editor decided to include a link to the Michelson-Morley experiment. Following that, the Aether was doomed to die. The main components of Relativity had already been laid by the likes of Lorentz and Hilbert. Even without Einstein I have a hard time believing that relativity would not have been formed at roughly the turn of the 20th century by someone else. It’s important to recognize that progress in physics never happens in a vacuum and the ‘big names’ we recognize today all contributed in a much wider field.

      • William F. Nappi

        Oh the many unsung heroes, too many to mention. Of the big names, Neils Bohr was one of my heroes; and talk about unsung: I CANNOT remember the name of the BRILLIANT son-of-a-gun (John Wheeler-Anderson something like that sound right to you?) who wrote such incredibly informative books in layman’s terms that I learned so much from.

        I feel like a near complete ingrate, as I feel, all things being relative of course, that I have a more reasonably strong background in this arena than the average citizen anyway. YOU, clearly have a strong command of this yourself.

        I just also wanted to let you know your comments are appreciated.

        • Zaoldyeck

          John Archibald Wheeler, close enough I suppose. I haven’t read his pop sci books but given he was Feynman’s adviser, I can’t be terribly surprised they’re quality reads.

          I fully admit my ignorance of the subject though. I have but a lame BS in the subject and while I have a habit of watching lectures or skimming through textbooks in my free time, that leaves me barely competent enough to discuss the subject with a first or second year graduate student, much beyond that and I start to admit I’m swimming in deeper waters than I should.

          However, because I understand my own ignorance, and because I’ve still studied the subject formally enough for me to be able to distinguish between sources of information, I can generally tell when people are making claims based out of a position of knowledge (that is, graduate student or better) or based out of a position of ignorance (generally, less than undergraduate student, or maybe to be charitable, first year undergrads)

          You don’t watch and listen to lectures by Aranki-Hamed or Sean Carroll without starting to understand not only how physicists think, but what words they’d use to actually express important ideas they have.

          I am no physicist, I want to make that clear. I just am currently an enthusiast who hopes to some day maybe follow in the somewhat odd footsteps of Queen Guitarist Brian May. (Who, naturally, has a PhD in astrophysics. Not that surprising when you listen to a song like ’39)

          Undergraduate degrees like mine mean almost nothing in the subject.

          • William F. Nappi

            Personally, I think you’re underselling yourself. As for Queen, wasn’t “You’re my Best Friend” on that same album? ‘Night At The Opera’ was first, THEN ‘Day At the Races’?

            No matter, a few great songs on both in my opinion. 39, though? DEFINITELY one of my favorites whichever one that’s on. Somebody stole my concert tickets to see them at Long Beach Arena back in late ’78.

            I’m over that now. Still love to read up on quarks though. Can’t get enough of that tiny stuff. I haven’t even made undergrad.

            I think some of those people are crazy. They DID get their degrees though. Thanks for sharing. It’s been interesting.

            • Zaoldyeck

              Not underselling myself, I am keenly aware that a BS makes me better than most laymen in physics, but leaves me hopelessly ill-equipped to deal with a lot of higher order physics. You don’t see me pouring over tensor analysis day after day but that’s the kind of practice I’d need to invest in if I wanted to have any hope of doing the subject at an appropriate level of rigour. The most I’ve got right now is ad hoc.

              ’39 is yeah on Night at the Opera and Brian May (who sings the album version) wrote the song explicitly about time dilation. It’s a sci-fi epic that’s rather accurate, which is kinda cool.

              Sean Carroll and Nima Aranki-Hamed did get their degrees, and then some. Preposterous universe is a great read, if you’re interested in more rigorous physics blogs than you’d get on a source like PBS. He’s not the best with updates but I quite like Sean’s author’s voice.

            • William F. Nappi

              And there I remained locked, but not locked in time (Shroedinger ‘cat’ reference) just ‘Liking’ 39 for it’s catchy beat.

              Do you suppose there was something else there all along (Time Dilation you mentioned) that I liked but didn’t realize?

              In closing, I have 2 questions:
              1. Do you have any brief thoughts or otherwise on alternate/parallel universes/multiverse(s)?

              2. Do you really believe that it is mandatory for one to have advanced degrees to understand higher order physics in order to have a plausible hypothesis on the matter of parallel or multiverses what I refer to as an alternate universe (as opposed to the more generally accepted terms for alternative universes?)

              Finally thank you for Preposterous Universe. I WILL look into that further. PBS and NOVA alike can get a little lax on what they let what it appears slip by in terms of fact checking from time to time.

            • Zaoldyeck

              *sigh* it’s 1am and my response was eaten so I’m gonna try to keep this somewhat short, finish a slice of pie and go to bed.

              ’39 constantly harps on you that something ‘unusual’ is going on… it’s an unusual story structure and lines like “don’t you hear my call though you’re many years away… write your letters in the sand till the day I take your hand in the land that our grandchildren knew” kinda makes it fairly clear something deeper has been going on… even if most people don’t stop to think about what it really is. (I mentioned time dilation and by that I mean 100 years have passed on earth for space-travelers who had only been gone a year. They’re in the land of their grandchildren, their loved ones are gone)

              “1. Do you have any brief thoughts or otherwise on alternate/parallel universes/multiverse(s)?”

              Not really other than any alternate/parallel/whatever universes must almost by definition not be casually linked to our universe so even if I’m thinking of many worlds or eternal inflation, I don’t really let universes which affect nothing keep me up at night. It’s not a terribly interesting question at this point in time.

              “2. Do you really believe that it is mandatory for one to have advanced
              degrees to understand higher order physics in order to have a plausible
              hypothesis on the matter of parallel or multiverses what I refer to as
              an alternate universe (as opposed to the more generally accepted terms
              for alternative universes?)”

              Yes. So strongly that it’s ALMOST without a caveat.

              I don’t mean the sense that the piece of paper is the requirement, rather, the process and knowledge you must acquire to obtain that piece of paper is the requirement.

              Notice that while I have little respect for my degree, and little belief that undergraduate physics education is worth anything to anyone, I am very VERY respectful towards the people I had teaching me. Anyone even somewhat intellectually honest in any half-way decent physics program will have the same feeling. When my friends and I would complain about profs, it’d be along the lines of “I cannot understand a single word he says” (Which was especially relevant for my electrodynamics prof who was literally a former USSR nuclear physicist… with the most perfect accent you’d ever expect or hope for from such an individual, even if you couldn’t understand a word he said… However, since the textbook was Griffiths, that really didn’t matter very much. Griffiths E&M is about as standard as you can get.)

              The longer you spend in a physics program the more you start to realize where each professor has their speciality. The more you realize what kinds of work is needed to understand different topics.

              Sure, without an undergraduate education, anyone could pick up vector calc or linear algebra pretty easily, but if you want to use those to build an intution to how physics works, it really REALLY helps to be able to ask questions, to find someone who knows the subject better than you and can clarify.

              …. That’s not even getting into the harder subjects, like topology or differential geometry, and while you (and I) can grasp that there’s this really REALLY interesting mapping between math and physics regarding “monstrous moonshine”, I admit I have no intuitive sense of what it means, just that there’s a fact that I’d like to one day gain an intuitive understanding of.

              That intuition doesn’t come magically, it comes with effort, and practice. It comes from reading textbooks, doing problems, and understanding what observables are even being referenced in your equations. Basically, the more ‘higher order’ you want to study, the more you need to essentially do graduate school studies, with or without that ‘piece of paper’.

              … So I suppose a person especially dedicated can find people to advise them, hang out on r/physics and the like enough, get textbook lists and run through them (INCLUDING DOING THE DAMN PROBLEM SETS!!!!… a message to myself as well as anyone else) and learn everything you need to know to be well informed.

              But since that requires obscene time commitments, the effort you’re spending doing that might as well be called graduate school, and given lost free time, it might be costing you the same amount as well.

              There are ways to be able to study the subject and have meaningful comments without the piece of paper, but in general, few people take that road, and even fewer of them who do have something interesting, correct, and counter-intuitive to add that hasn’t already been addressed by the formally educated community.

              “Finally thank you for Preposterous Universe. I WILL look into that further. PBS and NOVA alike can get a little lax on what they let what it appears slip by in terms of fact checking from time to time.”

              Sean Carroll is a physicist first, educator second, and a blogger third. He isn’t exactly the type of person who lets tons of loose facts and loose terminology slip into his commentary, it’s not like he maintains that blog to be world famous any more than Terence Tao maintains his blog.

              PS. I can read, and understand, some, if not most, of Sean’s posts.

              … Tao just makes my head spin in confusion and pain. I understand what the symbols mean in an objective sense but holy cr-p I swear a single line of his would require me a day to parse out and follow the rabbit hole of terminology and theorems required to understand it.

    • abc123

      Occam’s Razor states that answers “tend” to be simple, not that they must be. This principle has served us well thus far so I don’t think we should abandon it just because the true solution in one instance may not be elegantly simple.

      I agree that to eschew bias we must rely on the rigor of our methods and continuously work to better them. A true tabla rasa is not possible but is something to strive for.

    • johnny impactite

      exactly. And even the ridiculed ‘ether’ does seem to be as good a name for the fullness of the vacuum of space as anything nowadays with particles popping into and out of existence all the time. So they even got that one wrong,or are unwilling to still admit it. As well as Einsteins other really really big ‘that of which we shall not speak’ of thing, the negative side of his relativity equation, which he wanted nothing to do with, and Dirac solved. His cosmological constant was ridiculed and he even apologized sorta for coming up with it, only nowadays, again he is found to have been correct. his problem was a bunch of egos that outmatched his, that happened to be installed into minds that weren’t even in his league. The egos won.wrongly of course. Dirac showed that his equations were only for any one measured state and measured instance of matter or energy in that state, with the speed of light timesthe speed of light both above and below absolute zero the other possiblities, but Dirac also perfectly showed his univeral speed limit and all the other postulations as correct and true, for any one problem. It is hard to read new stuff after living through Einstein and Dirac, one expects, really more substantial discoveries and one gets mostly new speculation invariably driven by the latest macro ego trying to reach the top in a pseudo scientific turf war. I hate the wait while the chaff is being driven away by time, and younger would be gang leaders trying to topple the current shot caller. I long for Einstein, alas, he comes not. Where is our Einsteins these days? Are they selling sticks in Albania so their families may eat? Or perhaps prostituting for the same reason in IndoChina? We produced Einstein with a population of perhaps three Billion People. We have possibly three times that many now.We should have already produced at least two or three more. But apparently our stalwart EGOS have managed to keep them confined to menial labor at best and starvation or death by war, or disease or murder. Fate may not be so kind as to lay a humble patent clerk at our door next time, we may have to actively hunt him or her.