The Walter Issacson biography quoted Kip Thorne as saying if Einstein didn’t come up with relativity, likely no one would have for 30-40 years after. Which is insane and totally sensible. This theory had nothing to do with any observation or conundrum we could measure back then or even today except the weird discrepancy in Mercurys orbit. Truly a great genius with unparalleled originality. Somehow beats newton for this reason imo.
Great spoilers for the book Project Hail Mary below so stop reading if you’ve not finished it (and why havent you?): it was such a brilliant idea in that book to suggest that the space faring alien race never figured out relativity still and could still head out to a nearby star and only then discover there’s a massive discrepancy in their calculations. To use such an obscure observation that relativity is not obvious at all as a plot point needs a lot of kudos to the author.
> The Walter Issacson biography quoted Kip Thorne as saying if Einstein didn’t come up with relativity, likely no one would have for 30-40 years after.
Even for general relativity, it is not clear whether this statement is true, see
According to this Wikipedia article, it seems that David Hilbert came up with a different way of deriving general relativity at about the same time as Albert Einstein.
> David Hilbert came up with a different way of deriving general relativity at about the same time as Albert Einstein
But he did that only after having Einstein visit him for several weeks in the summer of 1915 and having long discussions with Einstein about the latter's ongoing efforts to discover a general theory of relativity. AFAIK Hilbert himself acknowledged that his final effort was only possible because of all the work that Einstein had already done.
The great insight IMO was special theory; the General Theory was I suppose a bit more obvious generalization that just needed the math to be figured out..
The necessary transformations for special relativity (Lorentz transformations) were already developed by Hendrik Lorentz and Henri Poincaré. Einstein's central contribution for special relativity was to reinterpret these equations in a novel way.
Exactly. The innovation was in belief that the theoretical could also be real, that the equations could be trusted. Just as with Maxwell predicting the speed of light or Darwin studying birds—these scientists had the courage to firmly state the conclusion implied by their work.
The fact that Einstein only took a fairly short time (IIRC less than a year once he started working on it in earnest) to develop and publish SR, whereas it took him ten more years before he published GR, strongly indicates that GR was much more difficult.
GR is much more heavyweight in terms of maths. But once SR was clear it was "just" an extension to the same ideas. The leap here was the original idea that gave rise to SR. The rest could have been worked out by most physicist of the time.
As compared to SR as Einstein originally developed it, yes. But note that modern usage of SR often makes use of the same differential geometry tools that were developed for GR--because those tools turn out to be useful even in flat spacetime.
> But once SR was clear it was "just" an extension to the same ideas.
Again, if that were the case one would not have expected it to take ten years to get to GR. Yes, Einstein had to learn about Riemannian geometry from Grossmann, but that didn't take him anywhere close to the ten years to do. He spent most of that ten years struggling with the physical concepts involved, not learning the math.
> The leap here was the original idea that gave rise to SR. The rest could have been worked out by most physicist of the time.
This is strongly contradicted by the fact that there were many other physicists working on a relativistic theory of gravity at the time--and they all got it wrong. Only Einstein, and Hilbert (who was a mathematician, not a physicist) after getting key input from Einstein, got it right.
> if Einstein didn’t come up with relativity, likely no one would have for 30-40 years after.
This seems like a hyperbole to make a point about how smart Einstein was.
From what I've seen in past discussions like this, including one on HN [0], is that it would've been delayed by 1-5 years. And it wasn't just the Mercury's orbit. There were fundamental questions about electormagnetism that had unclear answers with the predominant theory of aether.
Ive gone through the thread and dont see what supports your argument. The top comment quotes Einstein himself, but here’s his own final statement from that quote:
> The new feature of it was the realization of the fact that the bearing of the Lorentz transformation transcended its connection with Maxwell's equations and was concerned with the nature of space and time in general. A further new result was that the "Lorentz invariance" is a general condition for any physical theory.
This seems like a massive leap even given what Lorentz and Poincaré were coming up with, which is all at that point trying to understand what the math leads to and no real intuition on what that means in reality. Einstein on the other hand came up with something that had almost no mathematical underpinning (his first paper had no derivation). The final conclusion of the author in that comment, that this insight was only a year away, is thus completely unfounded in my opinion.
In that thread itself someone quotes Feynman concluding the same. I’ll listen to Kip Thorne, Feynman and my own intuition for now until someone gives a fairly thorough reasoning for their skepticism then.
I would also make a point of not quoting Einstein himself on such nuanced takes. He spent basically 30 years just commenting on his own theory and its motivations every single day. One would assume he would have decided to be more modest on some of those occasions in a mere whim or to placate that particular audience.
I have a ton of love for Andy Weir (Project Hail Mary, The Martian) for the exact reason you describe. Not only does he love the hard sci-fi bits but he clearly loves doing the homework so he gets it right.
Gravitational lensing and time discrepancies with atomic clocks, among others, would be obvious anomalies that would have led to relativity theories. Not to mention the actual speed limit of not being able to make anything move faster than light and the inability to find a reference frame for light to be moving in.
Once you start trying to measure the speed of light compared to your own speed it becomes quite obvious that there’s a problem with not being able to measure anything but c regardless of the movement of source and receiver.
We looked for Gravitational lensing only after Einstein proposed his theory and wanted validation. No one wanted to actually put the effort to do the measurement during an eclipse and iirc Einstein had to lobby for it greatly and only a single lone wolf guy took him up on it. And if I’m not wrong the initial observations weren’t even that solid and were likely artifacts that just in retrospect were interpreted in the right side of truth.
All other observations likely would have taken decades to stumble upon as well. I see no argument still why any other scientist would have made the relativity leap (which to be clear isn’t directly a requirement for deriving E=mC^2).
No, there were a lot of research already done on special relativity. Some even argue that Einstein genius was in reformulating what was already done and boldly putting the main equations first, instead of slowly working out of contradictions towards an equation at the end.
Was Einstein Right? by Clifford Will (disclaimer: know the guy a little bit), while it could use an update, is a fantastic review of the various experiments which showed that the results were within predictions of special and general relativities.
Many people don't want Einstein to have been right, and their motivations vary. Some really really really want FTL to be a thing. Some desire an absolute frame of reference. Some have philosophical issues with the concepts. A few seem to be under the impression that Michelson-Morley was done just the one time and that was the end of any attempts to falsify.
But nobody in the article disagreed with him about it. They disagreed with his complaints about quantum mechanics by making a comparison to relativity.
Yes. And that's completely fine. By the way, we know Einstein's theory of relatively is not quite right, there has been enormous amount of work since the early 1900s, its all good. Einstein's work was foundational, but incomplete, lets keep going.
Not necessarily. "Not quite right" implies that GR makes wrong predictions for experiments that have already been done--which is wrong. "Incomplete" just means that GR might not cover some experiments that have not yet been done.
"The theory, wraps all these errors and fallacies and clothes them in magnificent mathematical garb which fascinates, dazzles and makes people blind to the underlying errors. The theory is like a beggar clothed in purple whom ignorant people take for a king. Its exponents are very brilliant men, but they are metaphysicists rather than scientists. Not a single one of the relativity propositions has been proved."
Well Nikola Tesla thought a lot of physicists who created successful theories were frauds. He openly disagreed with Einstein, Marie Curie, Maxwell, Hertz... And probably a lot more that I don't even know about.
I think the most interesting thing about him is that, despite all his work in taming electricity, he disagreed with the existence of electrons (or really any subatomic particles).
Atomism is a philosophically offensive position to those of Tesla's personality type. Catholic Encyclopedia has an entry against it (while barely admitting an instrumental interpretation of atoms for chemistry). It's almost as bad as evolution!
Charitably I’m going to ascribe this to ignorance and not dishonesty. You may not be aware but Catholic dogma has no problem whatsoever with evolution, an old Earth, heliocentrism, or any number of other more or less fashionable opinions. The Catholic encyclopedia is over a century old and it shows. Perhaps you failed to understand the article you attempted to read? Nevertheless, here[1] is the entry on atomism for those who are interested.
The article immediately distinguishes between philosophy and science while you appear to be, for some reason, conflating them:
Atomism [a privative and temnein to cut, i.e. indivisible] is the system of those who hold that all bodies are composed of minute, indivisible particles of matter called atoms. We must distinguish between
1) atomism as a philosophy and
2) atomism as a theory of science.
It was neither ignorance nor dishonesty, my friend. It was measuring Tesla according to the beliefs of the Roman Catholic Church at his time in history.
And I mentioned "atomism as a theory of science" under the instrumentalism part of my comment. In Catholic Theology, philosophy always means "ontological interpretation". That section you quoted is saying that Catholics are allowed to believe in atomism as an instrumental model, but not as the ultimate interpretation of how the Universe works.
> In Catholic Theology, philosophy always means "ontological interpretation"
That's a rather bold claim. It implies that Catholic theologians are, among other things, uninterested in ethics, aesthetics, metaphysics, and epistemology, just to name a few other subjects of interest to philosophers. I'm frankly baffled that you would reach such a conclusion, but OK.
> Catholics are allowed to believe in atomism as an instrumental model, but not as the ultimate interpretation of how the Universe works
Well to be Catholic you have to believe in an ultimate eternal God, so ultimately we believe that everything in the universe is both created and sustained by Him and everything observable is some kind of instrumentality, be it evolution, quantum electrodynamics, or anything else. Nevertheless that doesn't in any pragmatic way restrict one's ability to form scientific hypotheses or theories. Indeed it's arguably closer to the Newtonian ideal of focusing on accurate description of phenomena.
The Bible, the Catechism, various works by Ambrose, Jerome, Augustine, Aquinas, to name a few, and the liturgical prayers of the Church to name just a few sources. I assume the Eva reference is meant to be mocking, but the Japanese artists who created it were very much intrigued and influenced by western theological and spiritual thought. Much like how many westerners are intrigued and influenced by eastern theological and spiritual thought.
In short, instrumentality deals with the how of God achieving His will. God, the incarnation excepted, is pure spirit, so in order to achieve His will materially He created and then used physical laws, among other things. The Big Bang is the greatest billiard break in cosmic history. So, for the well-formed Catholic, the possibility and apparent likelihood that God achieved the creation of Man using, among other instruments, evolution from lower life forms, isn't at all a problem.
Another example is Georges Lemaître[0] who "was the first to theorize that the recession of nearby galaxies can be explained by an expanding universe", as well as the Big Bang theory. These were not ideas Einstein favored, at least not at first.
An engineer from the previous generation seems like the last person to ask about a physicist. Being established and in a downstream field seems especially likely to induce an unjustified sense of confidence.
The experimental evidence for photons and relativity are, at this point, overwhelming. In addition to the usual examples, there's all the engineering that's explicitly uses the theory of photons; if there was something "wrong" with the "concept of the photon", why does the tech still work?
What that device is detecting is quantised interaction of light with matter. That is definitely quantised. However this interaction is quantised due to the quantised nature of the electron (e.g. the electron wave function can only have certain shapes). There is not good evidence (that I know of at least, maybe I will learn some) that the actual EM field is quantised.
As far as special relativity goes, the predictions of Lorentz ether theory and SR are identical. SR is basically a metaphysical theory that discards an absolute reference frame, while Lorentz ether theory keeps it.
> There is not good evidence (that I know of at least, maybe I will learn some) that the actual EM field is quantised.
I can't tell if you're pranking us, but of course there is. Without thinking too hard about experimental evidence: squeezed states and the Casimir effect both spring to mind. Hell, the photoelectric effect originally led Einstein directly to the quantization of the EM field. Or Compton scattering as another example.
The photoelectric effect and Compton scattering can both be explained with a semi-classical theory in which there are no photons. Can try and dig up papers if you are interested.
Not familiar with squeezed states.
The only quantisation needed in the Casimir effect is boundary-induced quantisation, that EM waves should have, right?
So Strnad is an interesting paper (I put the full cite as [1].)
My take after skimming [1] plus references therein, plus those that cited [1]: There is a cottage industry of papers trying to replay the early work on QED. Each paper takes one effect as it was known around 1930 or so, and then explains it using something other than QED.
I find the papers interesting in an academic sense. However, as guidance for how the world works, they build a box around the things they are trying to explain, but ignore the more difficult aspects of experimental data found after the 1930s. For the case of Compton, there are higher order scattering processes which lead to nonlinear Compton scattering, which happened in the 1960s.
To make a specific answer to your comment: My quick read is that Schrodinger's explanation fails at higher intensities, since the semiclassical treatment of E&M will increase only the amplitude of the radiation field, whereas nonlinear Compton scattering will need something in the way of additional terms or mechanisms to explain the experimental results.
More generally, that set of papers seemed to address only the singleton mechanisms but ignored the more general problem of noise and statistics. For example: Increasing the field amplitude in various experiments will reveal the shot-noise profile of photons, but I saw nobody try to approach that problem in my brief survey.
In any case, thanks for the reference. It lead to some interesting reading.
[1] Strnad, J. (1986). The Compton effect-Schrodinger’s treatment. European Journal of Physics, 7(4), 217–221. doi:10.1088/0143-0807/7/4/001
I haven't gone through any of the maths in detail. I do however have a semi-classical electrodynamics computer simulation that I occasionally work on, so why do the maths when you can just run a simulation :)
When I get back to it maybe I will try and simulate Compton scattering or the photoelectric effect.
> You can have vacuum fluctuations without photons.
Casimir is not about fluctuations. There is an attraction between metal plates in the absence of electromagnetic radiation.
And as I think it through, an even simpler example is the laser. Bose-Einstein statistics require that you have indistinguishable particles to multiply occupy a state. Without the indistinguishability, you don't end up with the right statistics. Without the right statistics, you don't end up with the right Einstein rate equations, and you'll be missing the stimulated emission term. Without that term, you will be missing the lasing action, as well as secondary effects such as noise statistics.
That would maybe be the best example, quantum entanglement is quite the mystery to me though (and to everyone?).
Maybe you can have entangled semi-classical fields? (e.g. fields entangled without intrinsic photon-like particles)
"if there was something "wrong" with the "concept of the photon", why does the tech still work?"
A theory can be wrong, or approximate, and still be useful for calculations and intuition.
For example Newton's gravity theory is wrong (or approximate) but still useful.
You have no idea what you’re talking about. Your feelings about the vague understanding you have of physics do not add to the conversation. Most of the technology you use every day depends on our understanding of quantum electrodynamics being correct.
Raising ether theories is usually troublesome especially pre-Lorentz concepts such as the luminiferous ether but one can't deny the fact that c = 1/√(ε0 μ0).
If we agree that this relationship is accurate then it seems to me that that just saying the vacuum permittivity and permeability are universal constants is a bit of a cop-out. If ε0 or μ0 change then so does c. Whether one uses the word ether or some other, there's something about a vacuum that's very significant/determines the rate of causality, etc.
Edit: seems to me if we had a better understanding of that relationship then we'd likely have an answer to the fine structure conundrum.
They both fit the data equally well, with the debatable exception of the cosmic microwave background, which debatably provides an absolute rest frame, thereby violating the SR postulate that all rest frames have the same laws of physics.
Yes, all the time and every time, that's how relativistic time dilation and length contraction works. Time dilation and length contraction are predicted by Maxwell's electromagnatic theory, it's no surprise they happen.
EDIT: not sure if you are familiar with relativistic length contraction and time dilation or not
You're using relativistic time dilation and length contraction to claim that Michaelson-Morley can be explained without relativity? Your logic sounds rather shaky there...
It is pretty hard to measure length contraction when all your measuring rulers also contract, and it's pretty hard to measure time dilation when all your clocks run slow, yes.
That is the conundrum of being embedded in the universe :)
> the cosmic microwave background, which debatably provides an absolute rest frame
It does no such thing. An "absolute rest frame" would be a rest frame that is inherent in the laws of physics, independent of the distribution of matter and energy. The CMBR only provides a "rest frame" in terms of its distribution of energy, and any piece of matter or energy will do that. For example, you, as a piece of matter, define a "rest frame"--does that mean your rest frame is absolute? Of course not.
Not that I’m agreeing with whatever was mentioned in the original comment, but as a semi outsider I feel we are indeed being disingenuous about this - what are quantum fields if not ether? I see no difference philosophically.
Like the fundamental original reasons why we went to quantum theory itself seems like we made some leaps in hypothesis (charged electron can’t orbit without losing energy, if the universe is filled with an ether then everything will slow down, etc) only to never actually solve that original conundrum ever.
Exactly, quantum fields are basically ether by another name.
The ether/aether word is just very out of fashion, having been allegedly 'disproved' (not actually) by Einstein and the Michelson–Morley experiment.
To be fair, some early conceptions of the ether included it flowing, like a liquid, which we don't think it does currently, and which quantum fields don't do.
If you have drunk the special relativity kool-aid, you might also be confused about how the ether/quantum field can be 'real' or something physical, if everything is relative. The Lorentz ether theory viewpoint helps with that confusion though, I think.
Individual quantum fields are not Lorentz invariant; they define distributions of matter and energy that look different in different frames.
The hypothetical ether of Lorentz ether theory, however, is Lorentz invariant: it is basically the vacuum in EM theory. So it looks the same in all frames. (Yes, LET claims that there is one particular frame that is the "absolute rest frame"--but there is no way of telling which frame it is because the ether looks the same in all frames.)
> Is there anything in quantum fields that directly demand them to not be Lorentz invariant?
To be more precise, any quantum field state except the vacuum will not be Lorentz invariant. That's not something specific to quantum fields: any non-vacuum state in classical special relativity will also not be Lorentz invariant. It will look different in different frames. That's just an obvious consequence of things like length contraction, time dilation, the fact that the energy and momentum of an object are different in different frames, etc.
Great spoilers for the book Project Hail Mary below so stop reading if you’ve not finished it (and why havent you?): it was such a brilliant idea in that book to suggest that the space faring alien race never figured out relativity still and could still head out to a nearby star and only then discover there’s a massive discrepancy in their calculations. To use such an obscure observation that relativity is not obvious at all as a plot point needs a lot of kudos to the author.