Physics, Chemistry, and Mathematics

Advances in the investigation of the physical universe we live in.
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Typhoon
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Re: Quantum weirdness

Post by Typhoon »

Simple Minded wrote:
noddy wrote:
Simple Minded wrote:
these types of replies kinda make me feel sorry for Typhoon as a moderator. PhD's must get lonely for intelligent, adult conversation at times.....
thats what talking to yourself is for.
also splains the fondness for girly pics.
Perhaps, but then how does one explain that the number of views for the girly pics thread greatly exceeds that of all other threads? :wink:
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Re: Quantum weirdness

Post by Simple Minded »

Typhoon wrote:
Simple Minded wrote:
noddy wrote:
Simple Minded wrote:
these types of replies kinda make me feel sorry for Typhoon as a moderator. PhD's must get lonely for intelligent, adult conversation at times.....
thats what talking to yourself is for.
also splains the fondness for girly pics.
Perhaps, but then how does one explain that the number of views for the girly pics thread greatly exceeds that of all other threads? :wink:
either you have good taste, or all OTNOTer's are closet scientists with PhD's......... probably the former. ;)
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Re: Quantum weirdness

Post by Typhoon »

Simple Minded wrote:
Typhoon wrote:
Simple Minded wrote:
noddy wrote:
Simple Minded wrote:
these types of replies kinda make me feel sorry for Typhoon as a moderator. PhD's must get lonely for intelligent, adult conversation at times.....
thats what talking to yourself is for.
also splains the fondness for girly pics.
Perhaps, but then how does one explain that the number of views for the girly pics thread greatly exceeds that of all other threads? :wink:
either you have good taste, or all OTNOTer's are closet scientists with PhD's......... probably the former. ;)
A third and simpler explanation: most of the viewers are guys.

Fortunately, a Ph.D. is not required. At least not yet . . .

Occam's Razor :wink:
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Re: Quantum weirdness

Post by Simple Minded »

Typhoon wrote:
A third and simpler explanation: most of the viewers are guys.

Fortunately, a Ph.D. is not required. At least not yet . . .

Occam's Razor :wink:
No doubt also true. But you are being too modest. :)

speaking of how quantum weirdness interfaces (yep, there's a pun in there) with pictures of hot women.......

http://www.news.com.au/lifestyle/relati ... 9244937207

I thought the internet was just one big virtual penis..... or maybe penii

HP, nother reason why ME people emigrate to the west.... :P

noddy, why do Stralians always break all the important news stories....
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Re: Quantum weirdness

Post by Typhoon »

Parodite wrote:
Typhoon wrote:As for QM, it has passed all precision experimental tests to date.
The rival local reality theories have not, and can thus be ruled out, and no one has proposed, despite nearly a century of criticisms, another viable alternative theory to QM. So until someone does, I'll stick with QM and leave the supposed philosophical questions and objections to others.
You misrepresent, and keep misrepresenting the controversy. No one tries to dispose of QM. Some physicists are not totally happy with qm because they feel it lacks ontological relevance. Or that it still not meshes well with macro physics and gravity. I'm just trying to figure out about the alleged quantum weirdness, what it is about and what not. A lot of smoke and mirrors there.
You're right that there is a lot of smoke and mirrors out there in that what you call "quantum weirdness" has attracted far more than it's fair share of crackpots on the internet promoting not-even-wrong expositions.

In macrophysics, quantum coherence is typically destroyed by the many-particle random position - momentum due to heat. The transitions to superconductivity and superfluidity as temperatures approach absolute zero are two examples of macroscopic quantum phenomena. I don't think that many physicists have an issue with this.

Quantum gravity is entirely another level of difficulty in that despite intense effort, since the earliest days of QM, no one has yet figured out how to properly quantize space-time.

A good lay survey of the problems and the current state-of-the-art with regards to attempts at quantum gravity:

What Are Quantum Gravity's Alternatives To String Theory?
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Re: Quantum weirdness

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Thank you for the links. Maybe there are also some fundamental questions left to be asked about quantization. What exactly happens when an atom jumps from one energy state to another for instance? When I walk from a > b the distance is covered in discrete steps. But jumping from one leg to another does not happen via magic steps emerging from a magical hat; there are transitions between those steps. Maybe ideas exist how this "discrete" jumping in qm occurs mathematically in an otherwise differentially calculated universe that you know of?

For us laymen I found those two excellent videos that go back to basics first and with historical background.

e5_V78SWGF0

FlIrgE5T_g0

Looking forward to the 3rd forthcoming on qm and its friggin' weirdness.
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Re: Quantum weirdness

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Parodite wrote:Thank you for the links. Maybe there are also some fundamental questions left to be asked about quantization. What exactly happens when an atom jumps from one energy state to another for instance? When I walk from a > b the distance is covered in discrete steps. But jumping from one leg to another does not happen via magic steps emerging from a magical hat; there are transitions between those steps. Maybe ideas exist how this "discrete" jumping in qm occurs mathematically in an otherwise differentially calculated universe that you know of?

. . .
I think you're trying to relate everyday experience to QM.

The two are fundamentally different.

A lot of clever people have spent a lot of time trying to come up with a supposedly more fundamental "gears, levers, and wheels" underlying mechanism for QM. Zero successful results to-date.

All evidence to-date is that QM is the fundamental description of nature.

Note that QM describes how, energy eigenstates in your example above, not why. This is physics in general.

In QM, one sets up and solves the time-independent Hamiltonian* to get the energy eigenstates of the system, for example, the hydrogen atom.

That's it.

Transition between energy states is by the aborption or emission of a quantum of energy - a photon of light:

Image

[The first three spectra are the emission spectra of excited gases of hydrogen (H), mercury (Hg), and neon (Ne), respectively.
The bottom spectrum is the absorption spectrum of hydrogen.]

*Hamiltonian mechanics
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Re: Quantum weirdness

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Typhoon wrote:
Parodite wrote:Thank you for the links. Maybe there are also some fundamental questions left to be asked about quantization. What exactly happens when an atom jumps from one energy state to another for instance? When I walk from a > b the distance is covered in discrete steps. But jumping from one leg to another does not happen via magic steps emerging from a magical hat; there are transitions between those steps. Maybe ideas exist how this "discrete" jumping in qm occurs mathematically in an otherwise deferentially calculated universe that you know of?

. . .
I think you're trying to relate everyday experience to QM.

The two are fundamentally different.
I expect that to be the case but am not there yet. Right now I'm cutting my way through loads of "not even wrong" nonsense, language abuse and PR of snake oil salesmen who sell QM as one would try to sell a magicians toolbox and manual. "A particle that can be a two places at the same time! A dickhead that goes through two sl*ts at the same time and interferes with itself! Come and see the magic!" 8-) (I understand.. they need funding too and want to raise public interest in their work)

Probably I end up in the agnostic church of Feynman... where simply no ontological claim is made about things unknown, unobserved/measured. But as a physicist there was no doubt in his mind: QM is very weird. Don't even try to make sense of it. But I defy my own expectations here and assume he was mad and surrendered to this God called Unknoweability. It is a religious kinda reflex when the going gets tough. :ugeek: (perhaps even a Jewish thing)
A lot of clever people have spent a lot of time trying to come up with a supposedly more fundamental "gears, levers, and wheels" underlying mechanism for QM. Zero successful results to-date.
I know. But it isn't clear to me so can't subscribe to that. Mechanics is supposed to be about gears, levers. and wheels. QM is also and still full of them. The particle-like behavior as observed in qm experiments for instance. Even the double-slit experiment is a purely mechanical event with causes and effects. They may not be totally understood but that doesn't make things necessarily weird or different from the usual gears, levels and wheels models that rule most of physics even today.
All evidence to-date is that QM is the fundamental description of nature.
But there is no gravity and general relativity in QM as of yet.
Note that QM describes how, energy eigenstates in your example above, not why. This is physics in general.
Progress starts with a why-question and then through observation, theory and experiment a how-answer emerges when results can be reproduced under controlled conditions. Then how-answers usually give rise to new why-questions and so science rolls forward. Why is the buck stopping at the eigenstates and no further why allowed or possible?

This is one of the things that intrigues me and for which there may be an answer: is there a "look no further beyond QM" because 1) in QM we have reached a practical limit to investigate these matters any further, 2) from QM theory and all experiment it follows naturally there simply isn't anything above or beyond the QM model possible; no hidden variables (local nor non-local), or other known and unknown unknowns are feasible. Usually one encounters the latter claim: but I haven't found the rationale or proof for that.

A physicist once explained it like this, as I remember it: In theory it is always possible that there is more physics involved in QM that we are not aware of but nothing to date points to what that could or should be. QM works and predicts fine without the need to add or remove anything.

I would think that in any case there is a practical limit to investigate the nature of very small systems and to how bigger systems behave as multi-particle quantum systems. But if an ontological statement can be made that the qm description is fundamental and complete... that is a bridge too far. Also given the problems of QM with gravity and general relativity.

It seems safer to assume that all theory and practice, also QM, are approximations within a limited domain of validity. I'm skeptical a theory of everything will ever be "complete" enough to satisfy everybody. The eternal "why" will always peep through the cracks.
In QM, one sets up and solves the time-independent Hamiltonian* to get the energy eigenstates of the system, for example, the hydrogen atom.

That's it.

Transition between energy states is by the absorption or emission of a quantum of energy - a photon of light:

Image

[The first three spectra are the emission spectra of excited gases of hydrogen (H), mercury (Hg), and neon (Ne), respectively.
The bottom spectrum is the absorption spectrum of hydrogen.]

*Hamiltonian mechanics
Yes, this is also explained in the two videos I posted on QM made easy.
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Re: Physics, Chemistry, and Mathematics

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3De1rLxvzyU
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Re: Physics, Chemistry, and Mathematics

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Awesome.. thanks.
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Re: Physics, Chemistry, and Mathematics

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Re: Physics, Chemistry, and Mathematics

Post by Doc »

CS I have a crazy question for you.

Do you think there is possibly a way to directly sensing potential chemical energy before it is released, in a universal way? For example like measuring a battery, but for all types of chemical energy. With a battery it is a matter of knowing the material it is made of. You measure the electric charge and knowing what voltage the battery against the known capacity of the battery. But in this case you would not know what the sample was made of but could still sense the potential energy it contains without knowing anything else about it.
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Re: Physics, Chemistry, and Mathematics

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Parodite wrote:
Parodite wrote:
Rather I found the article to be a clear exposition of the QM versus local reality issue and of the conceptual and technical challenges faced by the three recent tour de force experiments in testing Bell's Theorem.
Which means that when expirement reveals new information or verifies an existing predictive theory, it is about time to consider its meaning for physical reality.
It is not clear to me what you are trying to state here.
Well, the article does mention some ideas where future technology, if it works, would prove non-local instanteneous causation (or, to stay on the safe side, call it correlation) [my bold]:
The schemes demonstrated by the Vienna, NIST, and Delft groups have important consequences for quantum information. For instance, a loophole-free Bell’s inequality test is needed to guarantee the security of some device-independent quantum cryptography schemes [27]. Moreover, the experiment by the Delft group, in particular, shows it is possible to entangle static quantum bits, offering a basis for long distance quantum networks [28, 29].
It seems to me that this would truly be a revolution.
The experiments have ruled out local reality theories and provided strong evidence that QM as described by it's mathematics is how nature works.
But the experiments do not solve the problem of qm-gravity? at least not before the 2-spin graviton has been detected for starters.

Another thing that is mentioned in the article (and that appears to be down played a bit) that could spoil the fun is this [my bold]:
Of course we must remember that these experiments were primarily meant to settle the conflict between Einstein’s and Bohr’s points of view. Can we say that the debate over local realism is resolved? There is no doubt that these are the most ideal experimental tests of Bell’s inequalities to date. Yet no experiment, as ideal as it is, can be said to be totally loophole-free. In the experiments with entangled photons, for example, one could imagine that the photons’ properties are determined in the crystal before their emission, in contradiction with the reasonable hypothesis explained in the note in Ref. [18]. The random number generators could then be influenced by the properties of the photons, without violating relativistic causality. Far fetched as it is, this residual loophole cannot be ignored, but there are proposals for how to address it [30].
In your understanding, is this [the bold] a relevant possibility that can explain long distant non-local instantaneous/faster than light correlation? Of course Einstein maintained, up to his death bed, that faster than light causation or information transfer is impossible. He never liked "spooky action at a distance" for that reason. Did this experiment in Delft prove he was wrong there too?
Parodite wrote:
Regarding "an electron can be at two places at the same time" the accurate statement is that what one calculates is the evolution of the probability amplitude of the electron.
What I get from that is not that an electron has a probability amplitude but that what will be measured follows these probabilities.
From the point of view of the QM math, the distinction is not meaningful.
But Bohr, in his 30 years debates with Einstein, claimed that really nothing to very little can be said about the nature of physical reality such as "an electron" as it exists, may exist, independent from measurements in quantum experiments. The phrase "an eletron has a probability amplitude" is more how Einstein would say it. But then of course, he rejected the idea that electrons have probability amplitudes. He didn't like the idea of God playing dice. So they both would agree that probability amplitudes say very little about the nature of reality independent from scientific experiment, measurement and human observation in general.

But I understand your view on causal and/or ontological interpretations of QM. None of them ever added anything, changed anything; standard QM theory and application work like a breeze. Can't recall Feynman's exact words, but somewhere he says that it doesn't really bother him that QM is kinda weird, intuitively difficult/impossible to grasp. That also in Newtonian physics there is endless ontological mystery remaining. That all that matters in the end is what theory works and predicts best. "Shut up and do the calc". It seems to me he was an agnostic when it comes to interpreting QM beyond the math. I doubt he would claim that reality is probabilistic in nature.
I was not privy to Feynman's thoughts so I don't know. All I know is what he wrote:

http://www.feynmanlectures.caltech.edu/III_03.html

It is quite clear that Feynman has no issue with presenting a probabilistic interpretation of the canonical QM experiment and thus of nature.

Feynman, btw, developed an alternative [3rd] formulation of QM: the sum over histories a.k.a. the path integral method that is entirely equivalent to and consistent with the wave and matrix methods of Schroedinger and Heisenberg, respectively.

It is the one that is most used today in QFT.

This was his Ph.D. thesis work.
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Re: Physics, Chemistry, and Mathematics

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Doc wrote:CS I have a crazy question for you.

Do you think there is possibly a way to directly sensing potential chemical energy before it is released, in a universal way? For example like measuring a battery, but for all types of chemical energy. With a battery it is a matter of knowing the material it is made of. You measure the electric charge and knowing what voltage the battery against the known capacity of the battery. But in this case you would not know what the sample was made of but could still sense the potential energy it contains without knowing anything else about it.
I'm not sure that I understand your question. Would you please elaborate.
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Re: Physics, Chemistry, and Mathematics

Post by Doc »

Typhoon wrote:
Doc wrote:CS I have a crazy question for you.

Do you think there is possibly a way to directly sensing potential chemical energy before it is released, in a universal way? For example like measuring a battery, but for all types of chemical energy. With a battery it is a matter of knowing the material it is made of. You measure the electric charge and knowing what voltage the battery against the known capacity of the battery. But in this case you would not know what the sample was made of but could still sense the potential energy it contains without knowing anything else about it.
I'm not sure that I understand your question. Would you please elaborate.
OK You have package you don't know what is inside. Just that is full of say powder mix of some kind. Is there route you can think of to sense the chemical potential energy contained in the package like you can measure the energy of a battery. IE Does have the potential chemical energy of a bomb or that of a mix of sugar and salt? Like I said it is a crazy question. Just a more or less random thought I had.
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Re: Physics, Chemistry, and Mathematics

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Doc wrote:
Typhoon wrote:
Doc wrote:CS I have a crazy question for you.

Do you think there is possibly a way to directly sensing potential chemical energy before it is released, in a universal way? For example like measuring a battery, but for all types of chemical energy. With a battery it is a matter of knowing the material it is made of. You measure the electric charge and knowing what voltage the battery against the known capacity of the battery. But in this case you would not know what the sample was made of but could still sense the potential energy it contains without knowing anything else about it.
I'm not sure that I understand your question. Would you please elaborate.
OK You have package you don't know what is inside. Just that is full of say powder mix of some kind. Is there route you can think of to sense the chemical potential energy contained in the package like you can measure the energy of a battery. IE Does have the potential chemical energy of a bomb or that of a mix of sugar and salt? Like I said it is a crazy question. Just a more or less random thought I had.
To know the potential chemical energy inside the package you would have to know the chemical composition of the material inside.

If the containing package is non-magnetic then one might be able to use NMR [Nuclear Magnetic Resonance].

There is something of an industry trying to do this for chemical explosives; to detect them via some form of scanning.

One popular method is NQR [Nuclear Quandrapole Resonance]
which unlike NMR does not require an external magnetic field.

This method relies on the fact that the most common isotope of nitrogen [99.636%], 14Ni, has a nuclear spin of 1.
Most chemical explosives are nitrogen rich.
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Re: Physics, Chemistry, and Mathematics

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Massive [pun intended] physics news:

Einstein's gravitational waves found at last
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Re: Physics, Chemistry, and Mathematics

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Nobel prize for Einstein who predicted those waves to exist. A new era for physics is born.
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Re: Physics, Chemistry, and Mathematics

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Parodite wrote:Nobel prize for Einstein who predicted those waves to exist. A new era for physics is born.
Unfortunately, being deceased, Einstein no longer qualifies.

However, the three guys who came up with the LIGO concept are probable candidates.
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Re: Physics, Chemistry, and Mathematics

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Typhoon wrote:
Parodite wrote:Nobel prize for Einstein who predicted those waves to exist. A new era for physics is born.
Unfortunately, being deceased, Einstein no longer qualifies.

However, the three guys who came up with the LIGO concept are probable candidates.
Indeed & of course.
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Re: Physics, Chemistry, and Mathematics

Post by Typhoon »

First rate write up.

Quanta Mag | Gravitational Waves Discovered at Long Last
Ripples in space-time caused by the violent mergers of black holes have been detected, 100 years after these “gravitational waves” were predicted by Albert Einstein’s theory of general relativity and half a century after physicists set out to look for them.

The landmark discovery was reported today by the Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO) team, confirming months of rumors that have surrounded the group’s analysis of its first round of data. Astrophysicists say the detection of gravitational waves opens up a new window on the universe, revealing faraway events that can’t be seen by optical telescopes, but whose faint tremors can be felt, even heard, across the cosmos.

“We have detected gravitational waves. We did it!” announced David Reitze, executive director of the 1,000-member team, at a National Science Foundation press conference today in Washington, D.C.
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Re: Physics, Chemistry, and Mathematics

Post by Heracleum Persicum »

.

What I find so fascinating with Einstein, is, all kind of folks, from "MIT professor to dishwasher", all have some (more and less valid) opinion about all sorts of Einstein's theories .. in fact, in surface, Einstein's theories very simple to explain, understand AND visualize, for common (even illiterate) people.

.
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Re: Physics, Chemistry, and Mathematics

Post by NapLajoieonSteroids »

I thought LIGO was highly irresponsible in attempting to 'synergize' with the band Ok Go's new music video promoting gravitational waves

CUXafLUL5hs

released on the same day, coincidence? ;)
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Re: Physics, Chemistry, and Mathematics

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Great video.

Now, if only the music was not completely forgettable.
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Re: Physics, Chemistry, and Mathematics

Post by Typhoon »

The sound heard across the Universe.

https://soundcloud.com/emily-lakdawalla/ligochirp
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