Theoretical physics.

This forum is created for the purpose of discussing theoretical physics. Bring your hypothesis, your brain, and your manners, and have fun discussing the unknown and unknowable!

To start off, what are your opinions on string theory, quantum loop gravity, and GUT as a whole?

I've wanted there to be a grand unified theory since I was a student. The standard model of particle physics is inelegant and arbitrary looking to a mathematician, begging some sort of simplifying unification. However, a few decades later there is still no successful GUT and the standard model has survived.

The mathematics known loosely as string theory is the most attractive candidate as a basis for a GUT. IMO, its greatest success to date is being part of a solution of the black hole information paradox, and providing a value of the black hole entropy which is consistent with all other known physics.

Loop quantum gravity is a less ambitious theory, but one which is not so difficult to work with. It may be a good approximation to part of a GUT, but does not aim to be one. The least impossible way to get some understanding of LQG may be to read John Baez' writings. eg week 207.

Actually, John Baez says this is the best introduction to LQG. That doesn't mean it is easy for someone without a relevant graduate degree.

Yeah, all this stuff is pretty cool, but not for starters.

[I am replying to this post which was off topic in the evolution forum.]

If that's the Paul Davies book, it's probably reliable (barring typos). Who was the author of your book?

Davies says in the book "Superforce" that the GU scale is at around 10^14 proton masses, which is about 1.67 x 10^-13 kg, which corresponds to about 10^-29 meters, which is significantly bigger than the Planck scale. I think I have found what has happened. Your scale is probably given in seconds rather than meters. Converting using the speed of light, 10^-29 meters is equivalent to 3.3 x 10^-38 seconds.

Note (and this is a really neat thing you could learn) I did the above conversion by using the two equations:

E  = h_bar c / lambda   (= h_bar nu)

and

E = m c^2

This is how units are related in high energy physics. Very often they use units where c and h_bar are 1 to avoid arithmetic: you can look up the speed of light c and Planck's constant h_bar in SI units. The gravitational constant G is also used.

[The above should be comprehensible, but it is true that not only is LQM and string theory not for starters, it's not for all people who have a couple of relevant degrees! It's very, very advanced and beyond almost all of us, including me].

Since I am from computer science background, I would like to mention about quantum computation. All your electronic devices work on bits - 0 or 1 (low or high electrical signal respectively). Instead of decimal system, we have the binary system, for eg 1011 = 8*1 + 4*0 + 2*1 + 1*1 = 11. Information is stored in bits (memory). In this model, the problem of factoring an arbitrary number has no known efficient algorithm. But, using the celebrated Shor's algorithm, in quantum model, factoring can be done efficiently. And making this seemingly easy problem has widespread implications, like breaking of the cryptography algorithms currently employed worldwide. Papers leaked by Snowden pointed out large funding by US Govt in research of quantum computation.

In Quantum model, instead of bits, information is stored using the quantum states of an electron. Since we cannot pinpoint a electron in a particular quantum state, it is there with some probability, this supposedly adds a probabilistic power to the otherwise definite or deterministic (binary) 0/1 states model. Hence, factoring becomes efficient here due to the added power. 

Anyone a member of the Blikkiesfontein Avogadro's Hypothesis Club?By the way we also discuss Mathematics as well as Physics over a glass of ice cold Castle Lager.I know this thread is "Physics only"-but two issues which may be unresolved are these: 1) In Einstein's theory of Relativity (in which he claimed that the only "absolute" is the speed of light)what is the basis for a valid submission that that may no longer hold water?

                                              2).It has been argued that the earlier conclusion was that Pi is constant.This may have been eroded?On what credible basis has this been challenged?  

Next Friday there will be a talk by Professor Johannes Spengler on Boyle's Law.It will be at our Club.Time 19.30.Do attend if you wish.PS.Anyone coming?I must say I am singularly unimpressed by some of your debates on Quantum issues.Like pdela I don't understand what poopoofeira is going on about,Clarification please PooPoo!Are "lead pants" the equivalent of a steel jockstrap????That will go down well at our club.Could you please elaborate??? The more I try to analyse some of the contributions to this thread the more I am convinced it should be renamed "Gibberish Personified".Can't you guys do a little better?Waiting...Waiting...

The main advantage of quantum computing is probably that the amount of computation that can be done is exponentially related to the number of qubits. For a conventional computer the amount of computation is linearly related to the number of bits.

On the downside, it is very, very difficult to make a quantum computer with many qubits, even with all the knowledge that exists and plenty of funding going into this. Eg, as of 2016, google is involved in groundbreaking research using a 9 qubit computer. There have been claims of QC with much larger numbers of qubits - eg DWave's 1000 qubit computer - but most experts are skeptical these fully qualify. Theoretically, a 1000 qubit quantum computer should be capable of doing something many orders of magnitude faster than any conventional computer, but so far, DWave performance appears to be limited to a similar level to conventional computers (there is some dispute about this).

I actually independently invented a possible scenario for an ion computer. To my great dismay, however, I discovered a year later that some guy studying teleportation beat me to it.😁

I wish that I knew who wrote that book, as I said, I read it in a library one afternoon months ago, and don't remember it's author. It looked old, though. Maybe from the 90's?

Here is some cool math I did on the equations E=mc^2 and E=(lambda)p. After some dimensional analysis, and theorizing, I came up with this: M=(lambda)p/c^2. I love quantum physics, elemental particles are so fascinating! I've found that the Heisenberg uncertainty principle is a really cool way to say "don't know"on a test.

What are the 3 parts of a tensor? And the 4 parts of a quaternion. Tensors gain higher topological functioning in T. W. Barrett's Oscillator shuttle circuit theory, and I'd really like to know the step from vector to tensor, and tensor to quaternion.

Remember that dimensional analysis is a validity check, it does not tell you a formula is true! For example, You could write E = m v^2, and it would be dimensionally correct, but incorrect by experimental test.

Regarding tensors, I would strongly recommend studying linear algebra methodically and working up to tensors. Regarding quaternions, you can think of them as having 1 real component and 3 imaginary components. They are not a step beyond tensors, they fall into the sequence: real numbers, complex numbers, quaternions of what are called division algebras. The awkward difference of quaternions is that multiplication is not commutative: a * b is not always the same as b * a, as you can check by examples if you learn how to do calculations with quaternions.

Like complex numbers, quaterions can be used in many ways: one way is where the real component corresponds to time and the imaginary ones correspond to spatial dimensions. Quaternions are related to the symmetries of particle physics.

I'm physicist and I don't know what the hell is GUT

I imagine it's something about unified theory

That's a field with serious problems to give any experimental realizable prediction

same opinion about strings and quantum loops

You need a big accelerator there. Btw, weren't you into the "lead pants" part of the business, pdela?

I don't understand you pulpoferia