Lubos Motl turns on the sarcasm when he cannot grasp the problems with the version of special relativity string theorists use. Special relativity fails to apply to accelerated motion, and this flaw means you have to use general relativity which contains absolute acceleration. The only relativity generally (general relativity) is the equivalence principle: that inertial acceleration is identical to gravitational acceleration. If you are spinning, you feel centripetal force and thus can detect absolute acceleration. Acceleration is not relative like linear motion that special relativity applies to. Because all real motion involves starting and stopping, special relativity is inapplicable to ordinary motion. It is just valid for churning out the Lorentz transformation and E=mc2. It is not absolute truth.

*Lubos should read these views:*

‘The Michelson-Morley experiment has thus failed to detect our motion through the aether, because the effect looked for – the delay of one of the light waves – is exactly compensated by an automatic contraction of the matter forming the apparatus…. The great stumbing-block for a philosophy which denies absolute space is the experimental detection of absolute rotation.’ – A.S. Eddington, Space Time and Gravitation, Cambridge, 1921, pp. 20, 152. So the contraction of the Michelson-Morley instrument made it fail to detect absolute motion. This is why special relativity needs replacement with a causal general relativity:

‘According to the general theory of relativity space without ether is unthinkable.’ – Albert Einstein, Leyden university lecture ‘Ether and Relativity’, 1920. (A. Einstein, Sidelights on Relativity, Dover, 1952, p. 23.)

‘… with the new theory of electrodynamics [vacuum filled with virtual particles] we are rather forced to have an aether.’ – P.A.M. Dirac, ‘Is There an Aether?,’ Nature, v168, 1951, p906. (If you have a kid playing with magnets, how do you explain the pull and push forces felt through space? As ‘magic’?)

http://motls.blogspot.com/2005/09/why-no-new-einstein-ii.html#comments:

Nigel said...

Dear Lumo,You write that perhaps the reason why nobody has been able to convince string theorists of an alternative to string theory, is probably because there is no such thing.I've just read Dr Randall's "Warped Passages", and she credits you with proof reading.What struck me were her statements about half way through that since the strings are so small, accelerator energies achievable today are 16 orders of magnitude too low to test strings.In the concluding chapter, she gives a sample of the wide range of stringy ideas. The justification for 10-D string theory being equivalent to 11-D supergravity (Witten's 1995 work), giving rise to M-theory, is fine. I'm not worried about the 4-D spacetime being either a brane on 5-D spacetime, or the 4-D spacetime being a hologram of a 5-D spacetime. These mathematical equivalences are undoubtedly interesting to mathematicians, but the physics is simply not there yet.Dr Randall, despite admitting that ST energies are 16 orders of magnitude too high for direct tests, suggests indirect tests. These include energy balances. We all know that with so much 'dark matter' or 'dark energy' postulated by the mainstream model of the big bang (general relativity force-fitted to observation) the energy balances are not going to come from standard cosmology.Therefore, ST is a dead end. What would be nice is would be a review of the way in which general relativity models the big bang: starting from the observations. When you do this you see that the Hubble law in spacetime is not proclaiming the increasing velocity of galaxies away from us with distance, but with time past.Thus, the big bang can better be formulated from observations as an acceleration of matter outward in spacetime. The acceleration is equal to light velocity divided by age of the universe a = dv/dt = c/t = cH (because Hubble constant is H = 1/t, ignoring the correction factor or 2/3 or whatever applied for the slowing down of the expansion by gravity when gravity is assumed to be independent of the big bang).This acceleration allows us to calculate the outward effective force of the big bang by Newton's 2nd law F=ma. The 3rd law tells us that there is an equal inward force. This physically occurs because the spacetime fabric, such as higgs field, fills the 3-D volume around fundamental particles, and flows in to fill the voids left behind the particles as they rush outward.Thus we get an inward pressure from the spacetime fabric which gives rise to the force of gravity, since the pressure is shielded by large quantities of matter: http://nigelcook0.tripod.com/Weirdly, people try to use special relativity to discredit the spacetime fabric by claiming that "all" motion is relative, when in fact acceleration is not relative but absolute (hence the very reason why Einstein invented GR).One severe problem with 'special relativity' is that it is presented as the last word, as a disproof of reality. For example, in this big bang universe we are at an age of 15 Gyr, and everything we see is younger. The farther the star or supernova we see, the further back in the past it is, because of the time taken for the light to get here. So if we see two simultaneous supernovae, we can work out absolutely which happened first by knowing their distances! This is the exact opposite of the popular writings on 'special relativity' which say that you cannot tell which star exploded first.Another issue is absolute motion; the 2.734 K cosmic background radiation is 3 mK blue shifted in the direction of our absolute motion and 3 mK red-shifted in the other direction.So we can tell our absolute motion from that (about 400 km/s, partly due to the attraction of the Milky Way towards a big galaxy nearby, but if for sake of argument we have been going 400 km/s since the big bang - which is an order of magnitude approximation - we are only 0.3% of the radius of the universe, in other words within 0.3% to the middle of the big bang).This effect was called 'the new aether drift' (the title of a Scientific American article on the subject in the late 1970s). Critics responded by fiddling Copernicus' discovery. They claimed that Copernicus did not discover or work on the solar system, but instead had discovered that 'the earth is not in a special place in the universe'.Best wishes,Nigel

8:56 AM

Lumo said...

**Dear Nigel,your text is more or less OK until you write the following sentences:"**We all know that with so much 'dark matter' or 'dark energy' postulated by the mainstream model of the big bang (general relativity force-fitted to observation) the energy balances are not going to come from standard cosmology.

**Therefore, ST is a dead end**."I am completely lost in your reasoning and strongly believe that it is not my fault. ;-)The existence of

**dark matter and dark energy is a very probable fact that follows from the experimental data combined with general relativity.**General relativity is the correct classical theory of gravity. Most likely it is also correct for calculation of the dark energy and dark matter dynamics.

**Every quantum theory must agree with general relativity at these scales**.String theory does, and its vacua also offer natural new elementary particles that play the role of the majority of dark matter. At any rate, deducing that string theory is a "dead end" from your

**confused considerations of classical cosmology shows that your brain had to make a horrible mistake**, and I encourage you to think about it again because what you produced makes

**absolutely no sense**.OK, when I continued to look at your text, I also noticed that you want to

**disprove special relativity**. Hopefully you will find a better party to discuss

**your great ideas**. Good luck Lubos

9:30 AM

Nigel said...

Dear Lumos,Mathematically special relativity is correct, so neither I nor anyone else can disprove it.It is actually a crucial advance, but is misrepresented in a lot of physics courses as disproving the existence of a spacetime fabric, which clearly it does not do.Einstein made it clear in his Leyden University lecture of 1920 that space without a spacetime fabric is unthinkable.Another falsity of the popular presentation of special relativity is that it disproves the existence of all absolute motion, when in fact it only deals with non-accelerating motion. Acceleration induces forces which are absolute, if you have a force then there is acceleration. This is not subject to the relativity implicit in Maxwell's equations.General relativity is correct as far as it goes, but it takes Newtonian gravity as the weak field approximation. If there is a mechanism for gravity, that affects the constant G in the Newtonian theory and thus in general relativity. The test for this is whether the most distant galaxies, receding at nearly light speed, are being slowed down or not by gravity pulling them from within the universe.Since Perlmutter's results in 1998 for supernovae (using completely automated detection with CCD telescopes) disproved the prediction from general relativity, we know something is wrong.The official solution is that general relativity as it stands (pulling gravity) is right, and something is speeding up the galaxies to overcome gravity.The reality is that gravity is the shielding of an inward pressure of the spacetime fabric, generated by the mass moving outward. There is therefore no gravitational pull slowing down distant galaxies.Best wishes,Nigel

## 2 Comments:

There seems to be two types of accelerations, one which is the derivative of the velocity and should be relative, like the velocity. It can be measured optically, for example with a laser using the Doppler effect.

The other one is measured with a mechanical accelerometer, for example in a lift where the aparatus is at rest in the lift. Its velocity is zero but its acceleration is not. It seems to be absolute absolute since its value is the same as the optically measured acceleration.

There seems to be some contradictory. How to understand it?

Bernard,

"There seems to be two types of accelerations, one which is the derivative of the velocity and should be relative, like the velocity. It can be measured optically, for example with a laser using the Doppler effect.

"The other one is measured with a mechanical accelerometer, for example in a lift where the aparatus is at rest in the lift. Its velocity is zero but its acceleration is not."

All accelerations are the derivative of a velocity.

Where you say that for someone in freefall: "Its velocity is zero but its acceleration is not," you need to say what you are referring to?

Acceleration isn't the same as velocity, it doesn't have a velocity. dv/dt is acceleration, and velocity v = 0 while dv/dt is not zero.

Clearly if v = 0, then you would expect dv/dt = 0, so you would expect no acceleration.

But remember that an apple which is sitting on the ground with no velocity at all, has downward acceleration which produces a force called weight, F = ma = mg, where a and g are symbols for the downward acceleration, 32 ft/s/s or 9.8 m/s/s.

The crucial point you are making is that dv/dt can be non-zero when where v = 0.

Clearly calculus indicates that d(0)/dt = 0, so the weight of a non-moving apple should be F = ma = m*d(0)/dt = 0.

The apple is not moving because the electrons in the ground exert an upward reaction force by Coulomb repulsion which just cancels out the weight of the apple.

This "cancellation" of force is what stops the apple accelerating downward, giving a simple explanation of how a = d(0)/dt = 0.

However, the apple still has weight and there are effects from the "cancelled" (balanced) gravity and normal reaction forces which prevent acceleration; the base of the apple is being pressed against the ground, and there is some compression there, for example.

From the quantum gravity view, force is produced by impulses delivered by gravitons, not a continuously acting curvature of spacetime. This affects the mathematical model when using calculus as an approximation for the lots of little impulses due to discrete quanta of momentum being imparted.

Calculus is just approximate when you are using it to model discrete steps. Calculus relates to continuous variables, not discrete ones. Really, you should be using a model for acceleration using the sum of discrete impulses to replace the differential law.

The only way to properly understand physic is to start with the mechanism, and let the maths follow from that. Otherwise you end up chained to a false maths, which breaks down where you need it most at the frontier of research.

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