# Tag Info

8

According to Wikipedia: In particle physics, the history of quantum field theory starts with its creation by Paul Dirac, when he attempted to quantize the electromagnetic field in the late 1920s. [My emphasis.] And according to Wikipedia's entry on Dirac: He was the first to develop quantum field theory, which underlies all theoretical work on ...

8

This document (NB it's a pdf) contains details of the beam operation. Here's a key graph nabbed from the presentation: At the end of an experimental run the beam is dumped, and it takes about an hour and a half to get the beam back up to full energy and intensity. Once the beam is at full strength the LHC generates data continuously for somewhere between ...

7

No. There is nothing wrong with perturbation theory, or with theories with known, restricted accuracy. The point of theory is to explain the results of observation from as simple an initial theoretical standpoint as possible. Therefore: Since experiment always has a finite uncertainty, one can only ask that theory match the experimental value within its ...

5

QFT was formulated over many decades, from the 20's to the 70's, by many people from the USA, Europe and the USSR, amongst others. Although QFT is an active research topic, QFT was demonstrated to be consistent by 't Hooft in the 70's. Whilst particular achievements and developments are attributable to specific individuals, QFT was the result of innumerable ...

5

There is no significance in the choice between upper- and lower-case $\psi$ (or $\Psi$) to denote a system's wavefunction. The two are used interchangeably and it is the author's discretion to use either symbol. (On the other hand, of course, one shouldn't use the two symbols interchangeably within the same text; if both are used they would refer to ...

5

I'd expect you run it for a few seconds and bam - higgs boson detected or whatever. How does one detect the Higgs Boson? That's the question you must consider. Since a real Higgs almost immediately decays upon being produced, all we can detect are the stable decay products, those particles that last long enough to leave the vicinity of the collision ...

4

The whole volume XVII of the Proceedings of the Cambridge Philosophical Society is available on the Internet Archive at the url https://archive.org/details/proceedingsofcam1718191316camb It is p.43 as marked in the text and p.60 in the document. It is available in pdf, ePub, Kindle, Daisy and DjVu formats, as well as a dedicated (very nice) online ...

4

My suggestion, don't waste your time on it. Only from this Not only does the helical particle wave concept explain all the characteristics of light, etc., by means of a single model, but it allows one to calculate the exact position, velocity and spin of any relativistic particle without the need for such dubious concepts as: Einstein's time ...

4

Let's say you got fatter and fatter until you were the same mass as the earth, and, at the same time, the earth got smaller and smaller until it was only as massive as you were to start with. Now after this has happened, you must agree that you are now exerting a gravitational force on the earth (since you and the earth have now effectively switched roles, ...

3

Here's a useful link. For me, it's helpful to think there are clocks and rulers. The clock I have is the only one I have to measure time, and the ruler I have is the only one I have to measure distance, but you can think of space as being spanned by a big lattice of rulers, and if some of them get shortened or lengthened relative to others, there's no way ...

3

OK, I watched the video. It consists of two parts. The first part talks about General relativity and the introduction of a cosmological constant, which from the argument should not exist in completely empty space. He then goes to the Quantum Field Theory vacuum which has the continuous creation and annihilation of all possible fields of virtual particles ...

3

Muons are single-particle excitations (states) of the $e-\mu-\tau$ quantum field, except that these states don't have definite values of energy (they are in a superposition of states that have definite energy). Because states with different energies change at different rates, this superposition changes with time. After some time has elapsed, the ...

3

"iron magnets" are the regular kind of magnet. It's a rare-earth magnet, and the key ingredient in these is the rare earth metal. In this case, the Neodymium. One probably could replace the boron with something else and change the ratios a bit (probably getting a weaker but still effective magnet). The rare earth is what makes it so strong, so it is named ...

2

The experiments take many years. Using the Higgs boson search as an example, the reason it takes so long is because there is no "smoking gun" signature of a Higgs boson. You don't search for the Higgs boson directly, but for the Standard Model particles to which the Higgs decays. Since other Standard Model processes (called "backgrounds") can produce these ...

2

There's actually a FAQ for the LHC (CERN approved too). In that link , you'll see your exact question with the answer (all emphasis mine), When a proton leaves the source, it crosses the linac and reaches the PSB in a few microseconds. In the PSB it is accelerated from 50 MeV to 1.4 GeV in 530 ms, then after less than a microsecond it is injected in ...

1

Basically, the universe has a speed limit. No object can ever exceed the speed of light. Now imagine you decide to prove Einstein wrong by building a train capable of nearly reaching the speed of light, and then shooting a bullet forward in that train, so that the bullet will break the speed of light. In order to preserve this speed limit, time for you and ...

1

Both approaches are equally correct in this case. $F = mv^2/R$ is just a consequence of the law for rotational motion, which says $\tau = I\alpha$ (Torque = Moment of Inertia * Angular acceleration). The former formula may be used in case the objects in consideration are point masses. But the latter, more general version of the formula is applicable for ...

1

There will always be solutions that can't be analytical. For example, any model of more than two bodies without any special constraints, cannot be solved analytically. From the gravitational interactions between three planets to three particles interacting (electromagnetically or otherwise) in quantum theory. To have mathematically analytical solutions, ...

1

What I think you're trying to get at is the vaccum energy. Weight is always associated with a force, so on earth we feel the force of gravity on our body and we call that our weight. Now Einstein showed us that there is an equivalence between mass and energy. What we know from Quantum Field Theory is that there is some underlying amount of energy just ...

1

We do exercise a force on Earth. Let's say that the force in question is F. When F acts on you it provides an acceleration of F/m (where m is your mass) and when the same force F acts on the earth it provides an acceleration of F/M (where M is the mass of the Earth). As M >>>>>> m, the acceleration provide does not create some perceptive change in the ...

1

You're looking for experimental particle physics on a big detector at a national lab: There's no end to the custom electronics and embedded systems associated with the data acquisition, Computer science is definitely required (analysis of big data sets), and Plenty of really interesting fundamental physics. If you are still at the university go talk ...

1

Dirac's book was once thought to be a very hard book to understand (and because of its yellow cover, was called “the yellow terror”, an shared by Norbert Wiener’s book “The Theory of the Fourier Integral”) but is actualy an extremely lucid account. Its methodical treatment makes up for the lack of figures and pyrotechnics. Be prepared to read it slowly - ...

1

A process where the energy is kept constant is called isoenergetic (or, if you prefer, iso-energetic). It also seems from the literature that a flow where the energy is constant when following a fluid particle is usually called an isoenergetic flow. Similarly, when the enthalpy is kept constant, the process (or the flow) is said to be isenthalpic (or ...

Only top voted, non community-wiki answers of a minimum length are eligible