As per modern particle "physicists" - the scare quotes are because I no longer consider them to be physicists, though they occupy postdoc positions and professorships in academic physics departments, and publish in academic journals - a scientific explanation is of the form "If fact A requires B, then A is an explanation of B".

By chasing links from Peter Woit's Not Even Wrong you can find the culprits.

Let's look at an example:

Fact A = We earthlings exist. This requires

B = The earth's orbit is in the habitable zone around the sun.

Our existence, therefore, is an explanation of the earth's orbit.

Fact A = (Olber's paradox) - The night sky is dark, which requires

B = The universe is expanding.

(Olber's paradox is that if our universe is big enough (which it is) then any direction we look there should be stars, in fact, stars enough that the sky should be very bright. Read about it in Wikipedia. This example of mine is without explanation ruled to be somehow different from the previous example, btw.)

We can multiply examples.

Fact A = Airplanes fly, which requires

B = Airplane wings generate lift.

Therefore, the fact that airplanes fly, in the Brave New (Particle) Physics is an explanation of the lift generated by airplane wings.

I kid you not. Read Peter Woit's despairing lament about the descent of particle physics into pseudo-science.

__________

PS: A much better way of stating the problem is,

a. Suppose Fact A has no provided way of being a cause of B (i.e., Fact A is in the nature of an effect of B rather than a cause of B.)

b. Suppose Fact A requires B (i.e., the effect requires the particular cause B.)

c. Modern particle physicists, in particular, a large number of string theorists, regard A as an explanation of B.

## Wednesday, August 22, 2007

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## 3 comments:

Think of it like this. God proposes(stuff like reason, logic, intellectual honesty), Man disposes.

"... the fact that airplanes fly, in the Brave New (Particle) Physics is an explanation of the lift generated by airplane wings. ..." - Arun.

What about the foundations of physics: what causes fundamental forces?

The mainstream "explanation" is that the cause of gravity is basically that given in chapter I.5, Coulomb and Newton: Repulsion and Attraction, in Professor Zee’s book Quantum Field Theory in a Nutshell (Princeton University Press, 2003), pages 30-6.

Zee starts with a Langrangian for Maxwell’s equations, adds terms for the assumed mass of the photon, then writes down the Feynman path integral, with a Lagrangian based on Maxwell’s equations for the spin-1 photon and a mass term to make the maths work out without using the principle of gauge invariance. Evaluating the effective action shows that the potential energy between two similar charge densities is always positive, hence it is proved that the spin-1 gauge boson-mediated electromagnetic force between similar charges is always repulsive. So it works.

A massless spin-1 boson has only two degrees of freedom for spinning, because in one dimension it is propagating at velocity c and is thus ‘frozen’ in that direction of propagation. Hence, a massless spin-1 boson has two polarizations (electric field and magnetic field). A massive spin-1 boson, however, can spin in three dimensions and so has three polarizations.

Moving to quantum gravity, a spin-2 graviton will have (2^2) + 1 = 5 polarizations. So you write a 5 component tensor to represent the gravitational Lagrangian, and the same treatment for a spin-2 graviton then yields the result that the potential energy between two lumps of positive energy density (mass is always positive) is always negative, hence masses always attract each other.

I think this kind of "explanation" is not explanation but just a mathematical model for a physical situation.

It doesn't tell you physically in a useful (i.e., gravity strength predicting) way what is occurring, it doesn't explain the mechanism behind gravity in dynamic terms.

It's just an abstract calculation which models what is known and says nothing else that is easily checked.

For contrast, consider the physics of the acceleration of the universe. Mass accelerating outward implies an outward force (Newton's 2nd empirically-derived law) which in turn implies an equal and opposite reaction force (Newton's 3rd empirically-derived law), 10^43 Newtons. From the Yang-Mills theory, if gravity is a QFT like the Standard Model forces (Yang-Mills exchange radiation mediated forces) then the gravitational influence of surrounding masses on us and vice-versa is mediated by the exchange of gravitons.

By using known physical facts to eliminate other possibilities, you find that the 10^43 N inward force is likely mediated by exchange radiation like gravitons. This predicts gravity.

Galaxy recession velocity: v = dR/dt = HR. Acceleration: a = dv/dt = d(HR)/dt = H.dR/dt = Hv = H(HR) = RH^2 so: 0 < a < 6*10^-10 ms^-2. Outward force: F = ma. Newton’s 3rd law predicts equal inward force: non-receding nearby masses don’t give any reaction force, so they cause an asymmetry, gravity. It predicts particle physics and cosmology. In 1996 it predicted the lack of deceleration at large redshifts.

However, there is zero interest in physics, mechanisms, etc. Nobody wants to know facts, they want to read science fiction or fantasy.

The only big mainstream gravity journal to even have my paper refereed was the UK Institute of Physics journal,

Classical and Quantum Gravity,(where I submitted at the suggestion of Dr Bob Lambourne of the physics dept, Open University) the peer-reviewers of which rejected my paper as being "speculative" (yes, falsifiable predictions are speculative before they are experimentally or observationally confirmed, but the theory is fact-based) while having the temerity to (at about the same time) accept the Bogdanoff's nonsense (which they later retracted after printing it), "Topological field theory of the initial singularity of spacetime,"Classical and Quantum Gravityvol. 18, pp. 4341-4372 (2001).Physical Review Letters' editor Brown emailed me at university that the paper was an "alternative" idea and consequently unsuitable for publication. After a long correspondence, he forwarded me a report from an associate editor which claimed that some of my my "assumptions" (physical facts based on well-accepted observations and well-accepted mainstream theories) were questionable, but went silent when I asked which "assumptions" he was referring to.

These people are so certain that the probability any particular person has anything interesting to say, they don't bother listening.

It is actually clear what is occurring here. The required physical ideas aren't that clever, but the mainstream is convinced that the shape of the missing dynamics for gravity will be some amazing really hi-tech mathematical physics (a step forward coming from an abstract mathematical paper).

This has two effects: (1) it prevents the mainstream looking at natural questions which suggest find the required evidence, and (2) it means that anybody who does stumble on the missing facts (as I have) isn't able to publish properly in a mainstream journal.

I have published the paper elsewhere (Electronics World & Cern doc server). But even if I did get it in a mainstream journal, that wouldn't necessarily have any impact: people are good at ignoring new ideas they can't or don't want to understand (Boltzmann, Galileo, Bruno, Jesus, etc. being some examples).

One dubious advantage of this situation is the low plagiarism risk: anyone trying to steal really radical ideas will have the same problems. I don't think that even a top ranked physicist would have an easy time convincing others of facts; there is just too much prejudice out there.

It's not the mythical situation that you publish and everyone slaps their forehead and asks "why didn't I think of that?" Quite the opposite: people try not to think about things that lead somewhere, and if they think about anything at all it is drivel (non-fact based speculation).

Sorry about the length, and please feel free to delete this comment if it is damaging to your reputation to have it on your blog. I'll keep a copy on my blog.

Particle physics really can't live without new data. If the LHC finds nothing new, it will probably wither as a science. I remain an optimist, however.

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