- #1

- 19

- 0

- Thread starter MohammadK
- Start date

- #1

- 19

- 0

- #2

reilly

Science Advisor

- 1,075

- 1

For all practical purposes, the two names are interchangeable.

Regards,

Reilly Atkinson

Regards,

Reilly Atkinson

- #3

chroot

Staff Emeritus

Science Advisor

Gold Member

- 10,226

- 34

- Warren

- #4

- 13,017

- 566

Daniel.

- #5

George Jones

Staff Emeritus

Science Advisor

Gold Member

- 7,412

- 1,051

I think the titles of university courses have had an effect on which terms are used. A typical sequence of courses is: Quantum Physics; Quantum Mechanics; Quantum Field Theory. This gives the (false) impression that quantum physics is less advanced than the others.

As others have said, all this comes under the umbrella of quantum physics.

Regards,

George

- #6

reilly

Science Advisor

- 1,075

- 1

Regards,

Reilly Atkinson

- #7

- 19

- 0

- #8

- 1,548

- 0

NO this follows the Historical order of what came first and what is more fundamental. 1900/1905 to 1925 was the start and growth of Quantum Theory (or Physics if you like). To answer many questions not yet answered by QT, there came in 1926/27 Quantum Mechanics, a mathematical theory that could be there without QT first. As a response to problems some had with QM, came the growth of QFT. I believe at its core Field Theories are also “statistical problematic” (Throwing Dice), so it’s probably fair to say that QM uncertainty is fundamentally needed first for field theories.George Jones said:A typical sequence of courses is: Quantum Physics; Quantum Mechanics; Quantum Field Theory. This gives the (false) impression that quantum physics is less advanced than the others.

Where Einstein would have preferred to keep Quantum Theory “deterministic” or ‘local’ (not throwing dice) the only currently active theories

Thus QM is the root for all current theories, Strings, Standard Model, MWT, etc. And through QM therefore rooted in the original Quantum Theory. I don't believe we have any serious current theories (advanced or not) rooted in Quantum Theory without an element of the uncertainty principal of QM. But there could be, so no the names are not interchangable.

Last edited:

- #9

reilly

Science Advisor

- 1,075

- 1

Regards,

Reilly Atkinson

- #10

- 19

- 0

tuche.......................

- #11

- 1,548

- 0

Einstein would say it’s the different subjects that makes naming them correctly a big deal.reilly said:And, for goodness sake, what's the big deal if the three terms form an equivalence class? It's the subject matter, that to which the name is applied that is important.

He never had a problem with Quantum Theory, just the narrower subject area of Quantum Mechanics providing one possible answer to the questions of Quantum Theory. There is plenty of room within Quantum Theory for additional ideas that do not include the uncertainty of the Theory of Quantum Mechanics. But you shouldn’t expect to hear much about those ideas unless one merits being described as a theory by showing at least a little of the success that QM has shown.

Einstein never gave up on that. If he would have been successful, it would not have been QM anymore, but still a part of the Quantum Theory he’d original started with Planck etc.

RB

- #12

reilly

Science Advisor

- 1,075

- 1

I will grant you that historically there is the Old Quantum Theory of Bohr-Sommerfeld orbits, particulate photons and so on; and the New Quantum Theory of Heisenberg, Schrodinger, Born and Dirac. But the Old theory had lots of problems, so it's only of historical interest, one that is, I suspect in decline.

And, note QFT can easily be fit in to what you call the "narrower subject area of Quantum mechanics" It's all about the choice of Hamiltonian, and the representation of states -- like Fock Space for systems with indefinite numbers of particles.; the formal dynamical properties of QFT are well described by traditional QM/QT/QP-- see Dirac's book, many of the early papers by Heisenberg, Pauli, Dirac, Weisskopf on QFT and QED written in the 1930s.

Regards,

Reilly Atkinson

- #13

- 1,548

- 0

Reillyreilly said:RandallB-- Your take, I would suggest, differs from that presented by A. Pais in his wonderful biography of Einstein, "Subtle is the Lord....

..... note QFT can easily be fit in to what you call the "narrower subject area of Quantum mechanics" It's all about the choice of Hamiltonian, and the representation of states -- like Fock Space for systems with indefinite numbers of particles.; the formal dyna.....

I suspect you may have missed my point, that QM is a subset of theories within the larger set of theories contained within Quantum Theories.

I didn’t find any real conflicts in the reference you gave, just be sure to interpret statements like Einstein’s complaint about the “new quantum theory” as a complaint about “A theory” that is trying to interpret the whole of Quantum Theory correctly. That is, if you were to somehow invalidate QM though some falsifiable experiment it would not invalidate QT as there are several other non-QM approaches that might be useful to greater investigation.

Maybe part of the problem in the term “narrower”. Consider other sets of theories 1)Classical or 2)Mystical or 3)Canonic (Bible) Theories all three could be built within Quantum Theory. All 4 when we include QM are each ‘narrower’ than Quantum Theory, logical as they do not include each other. But “narrower” does not mean small. But due to not providing adequate real scientific results all above all are quite small, with the exception of QM. In fact QM is huge, because it has produced productive scientific results. But still a subset of QT.

I understand this may seem like semantics, but to scientists that should be important. You see it all the time in the popular press that Einstein didn’t: get, understand, was spooked by, had a problem with, never agreed with, Quantum Theory. It’s simply not true, he helped invent it and would have been excited by any interpretation of QT that might disagree with QM and help define what he considered “unknown variables”. It was QM not Quantum Theory in whole he had problems with. For a little more insight on the distinction try Louis de Broglie book “New Perspectives in Physics” (1962) as he reflects on his own history with QM vs. Quantum Theory.

RB

- #14

Leah

- #15

reilly

Science Advisor

- 1,075

- 1

Leah -- Do a Google. Quanum physics is what quantum physicists do.

Regards,

Reilly Atkinson

- #16

- 44

- 0

all semantics

- #17

- 1,548

- 0

I did (see post #8); I don’t see much problem using Quantum Theory or Quantum Physics interchangeably, at least not as bad as using Quantum Mechanics as being the same as either one.reilly said:Why not just say Physics?

........ I fail to see what in "Quantum Theory" would stay if, somehow, mainstream QP/T/M were shown not to be true.

I don’t see the logic in your other question. Taking your “QP/T/M” as meaning Quantum Theory and Quantum Physics and Quantum Mechanics all being shown not to be true, then of course nothing in Quantum Theory “would stay”.

The point is QM vs. QP/QT. QP/QT comes from Planck/Einstein 1900/1905 defining energy and even light as integer multiples of some smallest “packet or quantum of energy”. Later named a photon for light. The whole idea of light and energy coming in quantum steps, rather than a continuously measurable (dividable in ever smaller quantities) begs the question.

All the theory of Quantum Mechanics (1925+) does is attempt to answer that question.

If QM is somehow shown to be wrong, it would not invalidate the premise or questions established by the original wider area of QP/QT.

Now QM has done an impressive job at predicting statistical results by creating mathematical models that match observations. It has not been able to directly answer the question “How does that work”. Which is why there are so many additional theories within QM that are attempting to do so; Strings, M theory, 4D Strings etc.

The question QP/QT vs. QM deserves a better answer than “it’s all semantics”.

RB

- #18

- 574

- 1

- #19

- 35,847

- 4,670

Can you please cite for me any credible source where such an exercise in this dichotomy is actually done? Even from the philosophy aspect, I have never of no one spending time differentiating such a thing. When you open a "Quantum Physics" text, does it clearly say where quantum physics end, and quantum mechanics starts? Would you consider Schrodinger Equation to be in quantum physics, or quantum mechanics? Under what authority are you able to claim that there is such a distinction?RandallB said:The point is QM vs. QP/QT. QP/QT comes from Planck/Einstein 1900/1905 defining energy and even light as integer multiples of some smallest “packet or quantum of energy”. Later named a photon for light. The whole idea of light and energy coming in quantum steps, rather than a continuously measurable (dividable in ever smaller quantities) begs the question.How does that work?

All the theory of Quantum Mechanics (1925+) does is attempt to answer that question.

If QM is somehow shown to be wrong, it would not invalidate the premise or questions established by the original wider area of QP/QT.

This is like saying MRI is different than NMR. For a person who has no clue what those two are, the difference in semantics is everything. But for anyone who understands the PHYSICS of those two, there's no difference! Luckily, this is physics, and human language that is filled with unforseen connotations is often irrelevant. Physics is ALWAYS based on clearly, underlying mathematical description (look at the String theory that you were touting). This is the only thing that makes a difference. It is why I claim that QM (or quantum physics) cannot be understood if one is ignorant of the mathematics.Now QM has done an impressive job at predicting statistical results by creating mathematical models that match observations. It has not been able to directly answer the question “How does that work”. Which is why there are so many additional theories within QM that are attempting to do so; Strings, M theory, 4D Strings etc.

The question QP/QT vs. QM deserves a better answer than “it’s all semantics”.

RB

Zz.

- #20

selfAdjoint

Staff Emeritus

Gold Member

Dearly Missed

- 6,786

- 8

MRI and NMR are different beasties. NMR is Nuclear Magnetic Resonance, an experimental analytical technique. MRI is Magnetic Resonance Imaging, an exploitation of NMR plus other techniques to achieve biological imaging. To say they're the same is like saying television and electromagnetism are just the same.

Aside from that, any history that presumes to relate quantum history to some proposed distinction between quantum physics and quantum mechanics must also treat the "Old Quantum Theory" of Bohr. I do believe "quantum mechanics" was introduced when they could actually do Hamiltonians and such.

Aside from that, any history that presumes to relate quantum history to some proposed distinction between quantum physics and quantum mechanics must also treat the "Old Quantum Theory" of Bohr. I do believe "quantum mechanics" was introduced when they could actually do Hamiltonians and such.

Last edited:

- #21

- 35,847

- 4,670

OK, not to drag this down a different path, I still don't see the difference between NMR and MRI. As you have said, MRI is an application of NMR. NMR also isn't just ONE technique. It encompasses several different spectroscopy and imaging techniques, applied to everything from condensed matter to biological units, to engineering. When you measure the spin-lattice relaxation rate, it really doesn't matter if it's on a cancer tissue or a high-Tc superconductor, the physics remains the same.selfAdjoint said:MRI and NMR are different beasties. NMR is Nuclear Magnetic Resonance, an experimental analytical technique. MRI is Magnetic Resonance Imaging, an exploitation of NMR plus other techniques to achieve biological imaging. To say they're the same is like saying television and electromagnetism are just the same.

Aside from that, any history that presumes to relate quantum history to some proposed distinction between quantum physics and quantum mechanics must also treat the "Old Quantum Theory" of Bohr. I do believe "quantum mechanics" was introduced when they could actually do Hamiltonians and such.

Zz.

- #22

- 1,548

- 0

Common sense and basic logic.ZapperZ said:Under what authority are you able to claim that there is such a distinction?

(look at the String theory that you were touting)

And when have I ever “touted” string theory.

Can you site such a case.

- #23

- 1,548

- 0

Haven’t you answered your own question in the above statement. Drag out one of your old books from Logic 101.ZapperZ said:I still don't see the difference between NMR and MRI. As you have said, MRI is an application of NMR. NMR also isn't just ONE technique. It encompasses several different spectroscopy and imaging techniques, applied to everything from condensed matter to biological units, to engineering.

Premise : NMR & MRI are the same thing.

Given:

1) “MRI is an application of NMR” A technique achieving biological imaging.

2) “NMR also isn't just ONE technique. It encompasses several different spectroscopy and imaging techniques, applied to everything from condensed matter to biological units, to engineering”

Question:

Does MRI include “several different spectroscopy and imaging techniques, applied to…..” -- just as NMR does?

Answer: NO - MRI is just technique

Therefore the initial premise that “NMR & MRI are the same thing” is false.

In similar manner just because QM does not include the "Old Quantum Theory" of Bohr, does not mean the "Old Quantum Theory" is no longer a part of Quantum Physics. We just happen to living the part of scientific history right now that the only part of Quantum Physics that is under serious study is Quantum Mechanics. We don’t go back and burn all the books that might conflict with renaming QM as the Quantum Theory or maybe even just name it “Physics”. There is a difference and real scientists should be able to see that.

- #24

- 35,847

- 4,670

No, apply the UNDERSTANDING of what they are and you see why what you just said is false. If NMR is a bunch of techniques based on a common physics, then MRI is a part of it. To say that MRI and NMR is not the same thing ignores the PHYSICS that all of them are based on. The "imaging" that is done in MRI is nothing more than the SAME SPECTROSCOPIC measurement that is done in NMR, except that in most cases, MRI measurement does not care about absolute values of the measurement, but rather RELATIVE values of the measurement in relation to other values from different tissues, fluids, etc.RandallB said:Haven’t you answered your own question in the above statement. Drag out one of your old books from Logic 101.

Premise : NMR & MRI are the same thing.

Given:

1) “MRI is an application of NMR” A technique achieving biological imaging.

2) “NMR also isn't just ONE technique. It encompasses several different spectroscopy and imaging techniques, applied to everything from condensed matter to biological units, to engineering”

Question:

Does MRI include “several different spectroscopy and imaging techniques, applied to…..” -- just as NMR does?

Answer: NO - MRI is just technique

The physics is IDENTICAL. And considering we are talking about PHYSICS here and not how we SPELL a word, that is the criteria that *I* am using. What criteria did YOU use?

Zz.

- #25

- 1,548

- 0

YOURSZapperZ said:What criteria did YOU use?

Being a part of something is not the same as the whole.ZapperZ said:NMR is a bunch of techniques based on a common physics, then MRI is a part of it.

- Replies
- 5

- Views
- 2K

- Replies
- 1

- Views
- 616

- Replies
- 5

- Views
- 307

- Replies
- 4

- Views
- 720

- Replies
- 12

- Views
- 2K

- Replies
- 2

- Views
- 445

- Replies
- 7

- Views
- 2K

- Replies
- 33

- Views
- 4K

- Replies
- 3

- Views
- 1K

- Last Post

- Replies
- 3

- Views
- 260