Einstein, like no other physicist before or after him, demonstrated how the power of human thought alone, used skillfully, can make up for the lack of real experiments. He showed we little humans have the power to deduce equations that govern the natural world by logical conclusion. Thought experiments are common in theoretical physics today. Physicists use them to examine the consequences of a theory beyond that what is measureable with existing technology, but still within the realm of that what is in principle measureable. A thought experiments pushes a theory to its limit and thereby can reveal inconsistencies or novel effects. The rules of the game are that a) relevant is only that what is measureable and b) do not fool yourself. This isn’t as easy as it sounds.

The famous**Einstein-Podolsky-Rosen**experiment was such an exploration of the consequences of a theory, in this case quantum mechanics. In a seminal paper from 1935 the three physicists showed that the standard Copenhagen interpretation of quantum mechanics has a peculiar consequence: It allows for the existence of “entangled” particles.

Entangled particles have measureable properties, for example spin, that are correlated between two particles even though the value for each single particle is not determined as long as the particles were not measured. You can know for example that if one particle has spin up the other one has spin down or vice versa, but not know which is which. The consequence is that if one of these particles is measured, the state of the other one changes – instantaneously. The moment you measure one particle having spin up, the other one must have spin down, even though it did, according to the Copenhagen interpretation, not previously have any specific spin value.

Einstein believed this ‘spooky’ action at a distance to be nonsense and decades of discussion followed. John Steward Bell later quantified exactly how entangled particles are stronger correlated than classical particles could ever be. According to Bell’s theorem, quantum entanglement can violate an inequality that bounds classical correlations.

When I was a student, tests of Bell’s theorem were still thought experiments. Today they are real experiments, and we know beyond doubt that quantum entanglement exists. It is at the basis of quantum information, quantum computation, and chances are all technologies of the coming generations will build upon Einstein, Podolsky and Rosen’s thought experiment.

Another famous thought experiment is

**Einstein’s elevator**being pulled up by an angel. Einstein argued that inside the elevator one cannot tell, by any possible measurement, whether the elevator is in rest in a gravitational field or is being pulled up with constant acceleration. This principle of equivalence means that locally (in the elevator) the effects of gravitation are the same as that of acceleration in the absence of gravity. Converted into mathematical equations, it becomes the basis for General Relativity.

Einstein also liked to imagine chasing after photons and he seems to have spent a lot of time thinking about trains and mirrors and so on, but let us look at some other physicists’ thoughts.

Before Einstein and the advent of quantum mechanics, Laplace imagined an omniscient being able to measure the positions and velocities of all particles in the universe. He concluded, correctly, that based on Newtonian mechanics this being, named “

**Laplace’s demon**”, would be able to predict the future perfectly for all times. Laplace did not know back then of Heisenberg’s uncertainty principle and neither did he know of chaos, both of which spoil predictability. However, his thoughts on determinism were hugely influential and lead to the idea of a clockwork universe, and our understanding of science a prediction tool in general.

Laplace’s is not the only famous demon in physics. Maxwell also imagined a demon, one that was able to sort particles of a gas into compartments depending on the particles’ velocities. The task of Maxwell’s demon was to open and close a door connecting two boxes that contain gas which initially has the same temperature on both sides. Every time a fast particle approaches from the right, the demon lets it through to the left. Every time a slow particle arrives from the right, the demon closes the door and keeps it right. This way, the average energy of particles and thus the temperature in the left box increases, and entropy of the whole system decreases. Maxwell’s demon thus seemed to violate the second law of thermodynamics!

**Mawell’s demon**gave headaches to physicists for many decades until it was finally understood that the demon itself must increase its entropy or use energy while it measures, stores, and eventually erases information. It has not been until a few years ago that Maxwell’s demon was in fact realized in the laboratory.

A thought experiment that still gives headaches to theoretical physicists today is the

**black hole information loss paradox**. If you combine general relativity and quantum field theory, each of which is an extremely well established theory, then you find that black holes evaporate. You also find however that this process is not reversible; it destroys information for good. This however cannot happen in quantum field theory and thus we face a logical inconsistency when combining the two theories. This cannot be how nature works, so we must be making a mistake. But which? There are many proposed solutions to the black hole information loss problem. Most of my colleagues believe that we need a quantum theory of gravity to resolve this problem and that the inconsistency comes about by using general relativity in a regime where it should no longer be used. The thought experiments designed to resolve the problem typically use an imagined pair of observers, Bob and Alice, one of which is unfortunate to have to jump into the black hole while the other one remains outside.

One of the presently most popular solution attempts is black hole complementarity. Proposed in 1993 by Susskind and Thorlacius, black hole complementarity rests on the Gedankenexperiment main rules: That what matters is only what can be measured, and you should not fool yourself. One can avoid information loss in black holes by copying information and let it both fall into the black hole and go out. One copy remains with Bob, one goes with Alice. Copying quantum information however is itself inconsistent with quantum theory. Susskind and Thorlacius pointed out that these disagreements would not be measureable by neither Bob nor Alice, and thus no inconsistency could ever arise.

Black hole complementarity was proposed before the AdS/CFT duality was conjectured, and its popularity sparked when it was found that the non-locally doubled presence of information seemed to fit nicely with the duality that arose in string theory.

As of recently though, it has become clear that this solution has its own problems because it seems to violate the equivalence principle. The observer who crosses the horizon should not be able to notice anything unusual there. It should be like sitting in that elevator being pulled by an angel. Alas, black hole complementarity seems to imply the presence of a “firewall” that would roast the unsuspecting observer in his elevator. Is this for real or are we making a mistake again? Since the solution to this problem holds the promise of understanding the quantum nature of space and time much effort has focused on solving it.

Yes, Einstein’s legacy of thought experiments weighs heavily on theoretical physicists today – maybe too heavy for sometimes we forget that Einstein’s thoughts were based on real experiments. He had Michelson-Morley’s experiments that disproved the aether, he had the perihelion precession of mercury, he had the measurements of Planck’s radiation law. Thought alone only gets one so far. In the end, it is still data that decides whether a thought can become reality or remain fantasy.

[Cartoon: Abstruse Goose, Missed Calling] |

*This post first appeared on "Starts with a Bang".*

## 42 comments:

“Most of my colleagues believe that we need a quantum theory of gravity to resolve this problem and that the inconsistency comes about by using general relativity in a regime where it should no longer be used.”

Care to explain Sabine?

Why exactly you need a theory of QG?

Where is this regime where GR should no longer be used?

While it's certainly true Einstein was a great exponent of thought experiments, there were plenty that predate him. Galileo used them a lot, for instance, and Maxwell's demon is a well known example before Einstein got started.

Of course, technically Einstein's elevator is incorrect, as you can tell the difference between the two, provided you can measure gravitational pull sufficiently accurately to distinguish between the value at the top and the bottom of the elevator that is at rest.

But without doubt Dr E. was a wizard of the art form!

A good discussion of thought experiments: "The Laboratory of the Mind: Thought Experiments in the Natural Sciences"

http://www.amazon.com/Laboratory-Mind-Experiments-Sciences-Philosophical-ebook/dp/B0071WJGQ4/

"This principle of equivalence means that locally (in the elevator) the effects of gravitation are the same as that of acceleration in the absence of gravity."

JL Synge debunked this myth over 50 years ago in his GR textbook. As he pointed out, this is one of those statements that sound good, but fall apart when you try to specify what they mean. For example, the obvious interpretation is that the principle of equivalence states that the curvature tensor can be transformed away by means of a coordinate change. This version has the great virtue of being obviously wrong. At least it isn't "not even wrong"....

Converted into mathematical equations, it becomes the basis for General Relativity.

No, it doesn't. It doesn't contribute anything to our understanding of GR. It was important historically, but after 100 years it is about as relevant as Einstein's winged collars.

The only question now is this: why are physicists so obsessed with these antiquated gadgets? I'm told that there are still places where special relativity is taught by talking about trains being hit by lightning, sychronization of clocks and all the rest of that archaic bullshit. Why? Why not just talk about spacetime geometry? Is it because that sort of childish mythology gives some sort of illusion of having a deeper understanding than what the mathematics tells you? Or is it because a lot of physicists have a sentimental attachment to their undergraduate days? These silly stories really do a lot of harm.

Einstein’s elevators, the Equivalence Principle, assumes local vacuum isotropy. Drop two visually and chemically identical, solid single crystal balls - one space groupP3(1)21, the other space groupP3(2)21 alpha-quartz (space groupsP3(1) versusP3(2) gamma-glycine, etc.). Parity violations, symmetry breakings, chiral anomalies, baryogenesis, biological homochirality, Chern-Simons repair of Einstein-Hilbert action are consistent with vacuum trace chiral anisotropy acting only upon hadrons. Test vacuum geometry with chiral atomic mass distribution geometry, not with compositions and fields.Second Law of ThermodynamicsA hermetically isolated hard vacuum envelope contains two closely spaced but not touching, in-register and parallel, electrically conductive plates having micro-spiked inner surfaces. They are connected with a wire, perhaps containing a dissipative load (small motor). One plate has a large vacuum work function material inner surface (e.g., osmium at 5.93 eV). The other plate has a small vacuum work function material inner surface (e.g., n-doped diamond "carbon nitride" at 0.1 eV). Above 0 kelvin, spontaneous cold cathode emission runs the closed isolated system. Emitted electrons continuously fall down the 5.8 volt potential gradient. Evaporation from carbon nitride cools that plate. Accelerated collision onto osmium warms that plate. Round and round. The plates never come into thermal equilibrium when electrically shorted. The motor runs forever. (Gentle Reader must find the error. Good luck with that.)"Another famous thought experiment is Einstein’s elevator being pulled up by an angle."Appears that something was lost in translation. In English, "angle" is only "Winkel". Or did you mean an elevator pulled by an angel? :-)

"Where is this regime where GR should no longer be used?"You are a regular reader of this blog and are asking when GR is expected to break down? Really?

Answer: When quantum effects become important, such as at the Planck length.

"He had Michelson-Morley’s experiments that disproved the aether"Yes, but he repeatedly claimed that this experiment did not directly influence his formulation of SR.

"Of course, technically Einstein's elevator is incorrect, as you can tell the difference between the two, provided you can measure gravitational pull sufficiently accurately to distinguish between the value at the top and the bottom of the elevator that is at rest."Yes, or if you can measure whether or not the field is exactly parallel. This doesn't mean that GR is wrong, though, only that the equivalence principle applies in the limit of a vanishingly small elevator.

The problem of gedanken experiments is, they cannot lead to correct solution, when they're based on false premises, or when such a premises have holes (like the famous Feynman "beads of stick" gedanken experiment, and many others).

For example, in real observable Universe it's not quite true, that "..

to an observer inside the elevator, one cannot tell, by any possible measurement, whether the elevator is at rest in a gravitational field or is being pulled up with constant acceleration"It's true only for diehard fan of general relativity (which Mr. Einstein undoubtedly was) - but it has a very simple limitation, if you can think about it in open-minded way. Now, can you find this hole violating the EPR experiment?

...I see, Phillip Helbig has raised this hole already. Of course, it's a geometric problem of GR. Next time I will read the previous comments first.

So that the gedanken experiment isn't any miraculous solution for how to avoid the logical errors in your deductions. It's just a mental tool like any other - and you should handle this tool with caution. After all, Mr. Einstein wasn't first with his thought experiments, for example the Maxwell demon was here before it and IMO it's even more popular than the EPR.

The ancient Greek "deiknymi" was the most ancient pattern of mathematical proof, and existed well before Euclidean mathematics. Perhaps the key thought experiment in the history was Galileo's demonstration that falling objects must fall at the same rate regardless of their masses. This experiment is described by Galileo in Discorsi e dimostrazioni matematiche (1638) in form of discussion:

Salviati.

If then we take two bodies whose natural speeds are different, it is clear that on uniting the two, the more rapid one will be partly retarded by the slower, and the slower will be somewhat hastened by the swifter. Do you not agree with me in this opinion?Simplicio.

You are unquestionably right.Salviati.

But if this is true, and if a large stone moves with a speed of, say, eight while a smaller moves with a speed of four, then when they are united, the system will move with a speed less than eight; but the two stones when tied together make a stone larger than that which before moved with a speed of eight. Hence the heavier body moves with less speed than the lighter; an effect which is contrary to your supposition. Thus you see how, from your assumption that the heavier body moves more rapidly than ' the lighter one, I infer that the heavier body moves more slowly."He had Michelson-Morley’s experiments that disproved the aether"

This is also solely wrong - and not only because the Michelson-Morley’s experiments were a real experiments, not the thought ones. The actual problem with this interpretation is, it just puts the luminiferous aether concept on its head and it contributes to the widespread misunderstanding in this way.

The reference frame of luminiferous aether cannot be determined until such an aether really forms the space - i.e. not just pervades it as a sparse gas. If something forms the space, it cannot be detected with motion of this space, with its transverse waves the less. The transverse waves have no reference frame in any medium.

/* When quantum effects become important, such as at the Planck length. */

The quantum effects become important a much before at larger scales. Even the gravitational lensing is conceptually a quantum mechanical effect, violating the causality of GR with multiple light trajectories. The general relativity is valid only for intrinsic perspective of gravitational lensing and curved spacetime - once you'll appear outside of it, then you're getting into troubles with GR - no matter how small or large this lens actually is.

Zephir,

Two problems with your comment and where the thought begins and our experiments end as far as what is true provable or not, disprovable or not.

First most of the current debates in such physics (gravity, mass...) are there only because they apply to natural four space geometry. axiom: two planes can intersect at a point.

And what is necessary or vanishes when one logically turns concepts on their head (or in their head)...Axiom: two points can intersect in a sphere. These are angle questions but even in flatland we do not extended things to the three trisectors full circle.

Consider your logo again, as linear as it is. There are other ways to place such black and white circles on the number line. There are other relevant aethers so to speak.

Giotis, a lot can be said for Penrose taking the position we should modify the QM theory instead. Twistor space as the precipitation of gravity thus the reason, as the inverse square law of expanding integer windows is not enough.

Zephir: The logic of the universe is not the limitation you seem to think it is. But there are some even deeper number theory problems that only hint at answers for the physics.

Why is the sun most perfectly round? How can two spheres touch and this is determined if there is no internal structure of what is uniform?

Thought experiments always make me think of Schrondinger's poor cat.

/* Why is the sun most perfectly round? */

From the same reason, why the electron orbitals are perfectly round - it's an example of AdS/CFT correspondence (the shape of Sun is driven mostly with electron orbitals). We are observing the Sun from highest-dimensional intrinsic perspective possible at the entropic scale.

The Key point is here: "Yes, Einstein’s legacy of thought experiments weighs heavily on theoretical physicists today – maybe too heavy for sometimes we forget that Einstein’s thoughts were based on real experiments. He had Michelson-Morley’s experiments that disproved the aether, he had the perihelion precession of mercury, he had the measurements of Planck’s radiation law. Thought alone only gets one so far. In the end, it is still data that decides whether a thought can become reality or remain fantasy." Albert understood what make the difference, what is important and what is not.

We have a lot of information that Einsten couldn't even to dream.

Now we must learn the lesson and go on

Zephir said... "electron orbitals are perfectly round"

1) No.

http://www.chemistryland.com/CHM130W/03-BuildingBlocks/Chaos/Orbitals-f.jpg

http://www.chemistryland.com/CHM130S/03-BuildingBlocks/Chaos/Orbitals-d.jpg

2) Dunkelbumser.

3) http://www.youtube.com/watch?v=iM_I6rtIgn0

I always thought that information could be lost, but it requires the expenditure of energy to erase it. Biologists rely on this to understand cellular metabolism and mechanism. Granted I, and I am sure many others, have no idea of what it means to expend energy in a black hole. I seriously doubt there is ATP turning into ADP at the event horizon.

I can sure see how the idea of a Planck length could cause some problems with GR. It even gets me wondering what sense it makes with SR. It's a length for goodness sake. If something is two Plancks long in its own reference frame, and I'm approaching it at X% the speed of light, it might only appear to be one Planck long. Now what do we do? Split the difference?

Gedanken experiments are useful because they let you reason by analogy. They're metaphorical arguments, but so is any mathematical reasoning. They just let you choose more familiar, easier to work with metaphors. Of course, like the integers, real stuff is much weirder than we imagine.

/* Zephir said... "electron orbitals are perfectly round" no..*/

I don't think, your examples of orbitals are typical for Sun, they're rather typical for unstable stars of high metallicity.

Zephir,

The better reply would have been that the electron itself is "perfectly round to a very high degree"

We can turn the universe backwards that the hole through a torus contains the universe, and the universe that inside us... same for general states of mind of which we become isolated from more diverse views or without a social system that thrives as if a middle class the bounty vanishes while the people remain, perhaps in a dark illiterate age.

But good for you we stick to the science itself - although the purpose and use of this article is perhaps one of education and inspiration for thinkers to come. We rule by adapting to new ideas and sharing of our technology... and the best comes back to us or sometimes the worst too.

This was another great article well written, show some respect man, then again the old arguments are rather old and the opinions or objections have not changed that much to something like the M-M experiment.

Zephir,

I forgot to add that where there are metals in the sweet spot of galaxies it forms a ring, not a sphere, where life as we know it is possible.

Giotis: Is this a serious question? As to my guessing of your knowledge level, you clearly know the standard story: if the curvature (scalar, respectively higher powers of contractions) is in the Planckian regime, the perturbative expansion breaks down, theory becomes unpredictable, both singularities and bh inf loss are often attributed to this (which you might buy or not buy). Best,

B.

Brian: Einstein's elevator is a locally flat space. Of course this doesn't really exist. Neither does, for that matter, Laplace's demon, Maxwell's demon or Bob throwing Alice into a black hole. Best,

B.

Phillip:

Oops, thanks, I fixed that typo. You are clearly the most attentive reader this blog has ever had :) Best,

B.

Sabine again I’m talking about the specific excerpt of yours:

“Most of my colleagues believe that we need a quantum theory of gravity to resolve this problem and that the inconsistency comes about by using general relativity in a regime where it should no longer be used.”

The information loss problem is derived by using QFT on curved background. Nobody is “using general relativity in a regime where it should no longer be used” i.e. at the singularity; the problem is at the horizon and there you don’t need QG.

And the majority of physicists believe that the information is getting out somehow via the Hawking radiation.

So overall this whole excerpt is wrong as I understand it and maybe you had something else in mind, that’s why I asked for an explanation.

Giotis,

Was the horizon and flatness problem not addressed by Inflation theories?

GR applies here in the sense that it gives loopholes that make physical sense. So we know there such (mathematical) information escapes here. Perhaps in the general landscape QM in itself is inconsistent where it should no longer apply. Tegmark in conceptual physics addresses the state of our vision with levels of universe. At each level any model may end at consistency inconsistent on other levels.

I think Sabine at least asks some questions that apply with a higher level than the IVth to which a Vth would give better answers, loop wise and mathematics wise.

Would a region, sphere, in an inflationary universe not be viewed as an ending and not beginning which we may call issues of singularity?- in some baby universe regions for all practical purposes most are singularities or point defects of a general space curved or not? But let us face it, even at level five with the issues of infinity in a small volume ideas of information makes all of them toy universes or effectively quantized.

So many atoms out that we have copies of ourselves cannot distinguish these as if one initial (or terminating) self. Or recursive levels as self similar we cannot reach into the dark holes and wormholes but one way or direction to some fractal like hierarchy with constraints or not.

What information is technically lacking (Brian) in the top or bottom of such synthetic art. These great speculations are appealing and almost allow exact models in the normal chaos outside hidden zeros of calculations - but they are getting old now and not enough to explain gravity or something that persists over a range of stability as universe.

Hi Giotis,

I mean this sentence exactly the way I wrote it, and no it's not wrong. The problem is not the horizon, it's the singularity, but I know that 'most of my colleagues' do not agree on this. I have the vague impression we are arguing about the meaning of words. I have explained in my above comment exactly what I mean with the nontechnical phrase "using GR in a regime where it should not be used". I also said there, you (and 'most of my colleagues') might or might not agree that this is origin of the singularity and horizon problem, but the point is that we know GR breaks down at strong curvature. Best,

B.

Loved the cartoon.

Hi Bee, I've always thought that Schroedinger's Cat sounds a lot like Einstein's style - so I was pleased to learn recently that Einstein explored something quite similar in a letter to Schroedinger, before the famous paper (he used gunpowder and no cat)..

Regards, Cormac

I have trouble understanding you; probably you propose baby universes or remnants but these solutions are among the least favored in the Physics community so I really don’t get it why you are saying in your article that the majority of your colleagues agree with you.

Giotis,

Should we care what others believe in a consensus? At best it makes me think I have commented here without understanding the positions at all. I do wonder how from some position others want to declare, share, impose it on others, the good news perhaps, a simple question of deceptive sequences that build up like a vibrating dipole antenna until it radiates the signal short of time.

It is dramatic, archetypal and stereotypes meeting somewhere in unity perhaps. The second philosophy (science) seemingly explained as a living one... our holding our empirical ground "homo faber" to make or get something done, technically.

Einstein's genus was just this. As an example caught in history and cultural transition- a son of both worlds looking for a little unity in the chaos. What he says of physical things much more than that abstract.

Abstractly Black Holes exist for they are what is left over of a count of null regions (that is squaring them, and theoreticians try to build models discovering the deepest things that seem to be there on their own so as to understand others.) provided we take the sequence a little further than the obvious first few dimensions.

We can build a structure, polyhedron say, all its faces but the last one and that from the inside only. Or we can mystically dwell in the last face and physically construct the rest.

Our alphabets of finite organization encompass an infinity of dreams that in a sense requires things quantized as a possible solution (and new ideas given peace enough to discover them) but here different symmetry ideas conflict still... the letter of such alphabets formed from our mouths or much earlier gestured by our tool making hands.

Hi Giotis:

I think you're misreading me, let me try to clarify this. I think that "most of my colleagues" would agree that the reason we encounter a black hole information loss problem and singularities in GR is due to us missing a theory of quantum gravity. Thus my statement that we need quantum gravity to resolve these inconsistencies that we encounter, etc. We poke around on black hole information loss because it is often considered a key problem, one whose solution will bring us a big step towards quantum gravity - thus the relation to this post.

I keep putting "most of my colleagues" in quotes because, needless to say, I didn't make a survey, so this is just my impression from talks, conferences and the arxiv etc.

Yes, I also think that pretty much everybody except Bill Unruh believes the information comes out with the radiation.

Now as to myself, I think it is pretty clear that the origin of the bh infloss problem is the singularity and not the horizon. The horizon is where information becomes disconnected from the outside observer, but the actual problem is that it gets ultimately lost and erased at the singularity. Remove the singularity and you remove the information loss.

That in and by itself however doesn't explain how the information comes out. Yes, I think a remnant solution is the most plausible one. No, I don't think the pair production problem is a problem. Because that alleged problem really comes about by using effective field theory in a strong curvature regime, at the singularity and not at the horizon. No, I don't believe in the strong interpretation of the bh entropy, and no, then there are of course no firewalls and other nonsense. Hope that clarifies it. All of this is btw well documented in my 2009 paper with Lee.

Best,

B.

Nemo: Yes, in fact that was the whole point of this post, seems that most readers missed it though :)

"You are clearly the most attentive reader this blog has ever had :)"Just wait until I get one of your papers to referee. :-)

Hi Bee,

Your Blog post entry reminded me of a couple of things that had already been written.

Of course Angels and Demons the movie by Tom Hanks. I know you did not mean this so one has to go further back.(an insidious plan to capture the anti-matter)

Escher's image is there to remind us?

Just some of the thoughts that came forward.

Einstein just made use of somebody who saw farther, and united a classical view using the euclidean world and helped us "to see" differently. Of course Einstein made use of this.

Where would we be then without Gauss and Riemann? Escher?

Best,

Anybody whom had solved any scientific(or even non-scientific ) problem knows that some sort of an experimental thought went on in the brain. Then you take an action, say by scribbling, to find out if that experiment was good or it needs correction/modification.

All kinds of strange "experiments" went into my head to come up with this

(proton-electron mass ratio=1836.152672)

1/ alpha =(M_p/M_e)/(3^3/2)+1+2/(3^2*3^2)=137.036000

What

would Einstein, if he lived today,

call "his biggest blunder"?

Cosmological constant or thinking that

"spooky action" is a reason against

quantum theory?

Regards

Georg

Alice,

Remove the singularity and you remove the information loss. - B

Ok.

Of course the next step is 'why stop there?' Obviously, you and all of your colleagues never did and never will [stop] until THE model arrives that serves what you all seek.

You are the culmination of pragmatism and clarity.

No fooling yourself or others.

"Mawell’s demon gave headaches to physicists for many decades until it was finally understood that the demon itself must increase its entropy or use energy while it measures, stores, and eventually erases information." - B

The [life sciences]analog to Mawell’s demon is repair.

The main driver of all bioevolution, all biodiversity and all cell differentiation is repair.

Each and every one of your cells repairs itself on the average sixty thousand times daily.

Why stop there? All cells repair.

The demon itself for all of the life sciences is repair. The understanding that "the demon [repair]itself must increase its entropy or use energy while it measures, stores, and eventually erases information."

No repair, no aging.

No repair, no life.

No repair, no thought [experimental or otherwise]

I'm glade someone created an inequality that helps us assert that we can correlate above and beyond that what the classical correlations provided us before.

Self derogatory in closing,

Bla, bla, bla,

blog, blog, blog,

Bob

Dear Sabine,

Something has been puzzling me for a long time concerning a thought experiments such as Einstein's in special relativity :

An observer in the frame of the train moving away from the station.The situation is supposed to be Lorenz invariant :

Trainguy cannot distinguish between the train moving away or the station moving away, therefore the effects experienced in the station frame are concluded to be the same as those in the train frame. My problem is that the thought experiment extrapolates the conclusion from one specific type of observer to all every day common observers. I explain : Isn't knowing something to be impossible equally valid as not being to distinguish by observation ? What i mean is this : If trainguy decides that now it is the station moving away from him, then he has no problem with the following that would happen : the station is attached to the earth, and so the earth would start to rotate faster or slower, and/or would suffer a slight shift of the north-south axis, as 'the station moves away' in a certain direction.You cannot escape that conclusion as a 'normal' observer. Yet the observer in the thought experiment seems to have no problem with this at all. He has been handicapped intellectually, compared to the every day observer. I would therefore conclude that we cannot derive anything usefull from this thougth experiment, consequently the invariance can not be proven this way. What this thought experiment is doing is the same thing as this : Imagine men walking through forests, having blindfolds on. After 5 minutes they start hitting their heads against trees. We conclude : "Men walking through forests will start hitting their heads against trees wihtin 5 minutes...:you have extrapolated the conclusions consequences for the handicapped observers in the thought experiment to every day observers in the real world. Whith this technique you could prove anything to be true.

So why do we accept the usefullness of Einstein's thought experiment ?

A question alongside of this : We have plenty of experiments proving the time dilatation effect in similar 'earth-train' frames where 'the train' is moving away. But as far as i know , not a single experiment exist where 'the station clock' proved to run slow compared to 'the train clock'(in the case where trainguy would decide that day to have the station move away from him, so again no direct proof of the invariance.

Shouldn't we have mathematics guided by solid logic, (and vice versa), in order to really learn more about the functionalities and causalities of motion ?

Greetings, K.M.L.L. Van Spaendonck

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