## Tuesday, July 06, 2010

### Hossenfelder vs Smolin: a miniwar on DSR continues

You know, Sabine Hossenfelder is not exactly what we could call a good physicist - and not even an average one - but relatively to Lee Smolin and others, she ends up being the genius of the day.

She has written several papers explaining the most obvious fact about DSR: that its modified Lorentz transformations imply nonlocalities in nearly all reference frames that contradict the basic facts about particle physics (e.g. the fact that you can decide whether a cosmic ray particle was caught in a box or not).

In December 2009, she wrote
The Box-Problem in Deformed Special Relativity
One preprint cited her for some strange sign only. However, all the remaining five followups of the paper above belong to the "DSR vs Hossenfelder" war, so they're written either by DSR fundamentalists or by herself.

In April, she wrote an updated article about the same issue,
Bounds on an energy-dependent and observer-independent speed of light from violations of locality
which was quickly criticized in an April 2010 paper by Smolin. Her December paper was also semi-criticized in an April 2010 paper by Jacob, Mercati, Amelino-Camelia, and Piran.

In May 2010, she would write a comment on comments,
Comments on Nonlocality in Deformed Special Relativity, in reply to arXiv:1004.0664 by Lee Smolin and arXiv:1004.0575 by Jacob et al
while yesterday, Lee Smolin wrote his new repetition of the same old misconceptions,
On limitations of the extent of inertial frames in non-commutative relativistic spacetimes
Of course, the value of all these preprints is pretty much zero. They're explaining trivial things - and except for Hossenfelder's papers, they're wrong, too. But all of them are immensely repetitive.

Although she's extremely unlikely to be the person who has actually found these things for the first time, and even your humble correspondent wasn't (see e.g. TRF 2006), Hossenfelder is absolutely correct in all these flamewars. It's kind of amazing to see how Lee Smolin is totally unable to falsify wrong hypotheses even in the simplest cases.

Take his newest preprint by Smolin and open it on page 10.

After you realize that the uncertainty of time coordinate is called "1/omega_0" because the author (incorrectly) thinks that classical clocks with frequency "omega_0" can't be more accurate than by "1/omega_0", and after you reshuffle a few illogically written formulae, you will realize that on that page, Smolin claims that DSR implies an inherent quantum gravitational inaccuracy of the time coordinate of an event that is of the order
error(time) = Delta E / E_{Planck} times distance
in "hbar=c=1" units. Here, "Delta E" is the difference between the energies of the particles involved in a process. For example, for the "Delta E = 31 GeV" photon in the Fermi observation that proves the Lorentz symmetry at the Planck scale, "distance" is 10 billion light years or so and the error in time ends up being 0.8 seconds or so.

That's way bigger than the actual upper bound on the delay that the separation may produce - which was measured to be at most 20 milliseconds or so and it is almost certainly zero.

While 0.8 seconds doesn't seem like too much, it translates to 240,000 kilometers. That's the uncertainty in the position of an event that a distant observer will see. Of course, one doesn't need distant observers like that. Even for nearby sources of the radiation, you can get smaller yet unacceptable uncertainties of the position. Large boosts make the situation even worse, essentially by the factor of "gamma". That will prevent two observers in relative motion to agree whether a cosmic ray particle managed to be caught in a box, among other things.

Clearly, such ambiguities - and transformations of particles out of boxes where they were caught - can't exist.

Lee Smolin just isn't capable to see the problem. The second, last paragraph of his newest abstract says:
These ambiguities grow with distance and only become relevant for real observations for the description of cosmologically distant events. They do not afflict the interpretation of the detection of gamma rays in stationary or moving frames near the detector. Consequently there is no disagreement between the principles of DSR and the observation that interactions in nature are local down to currently observable scales.
This makes no sense whatsoever. The laws of physics must allow us - and do allow us - to talk about phenomena at distant places, too. If we can derive a contradiction about events that are one astronomical unit away or 10 billion light years away, it's still a contradiction.

Of course, Mr Smolin may try to hide into a sphere of radius 0.01 L_{Planck} and believe that his "physics" is just doing very well inside the sphere and everything outside the sphere is unphysical and ambiguous. But those who live outside the sphere know that there is a lot of physical phenomena that take place outside the sphere and that should be correctly explained by physics - and moreover, Smolin's sphere doesn't exist because distances shorter than L_{Planck} are those that are unphysical. ;-)

As always, it's hard to unambiguously say whether Mr Smolin is so incredibly dumb that he can't get these simple points, or he realizes that he's wrong but he's just defending his previous indefensible opinions because of egotistic reasons. The answer is that the trouble with physics is that there are two Lee Smolins rather than one.

One of them realizes the problems - including those emphasized by Sabine Hossenfelder - very well. He knows that the "uncertainty" of the position that is presented as a cool prediction should be called "nonlocality" and it is a lethal problem of DSR. The other Smolin doesn't realize it; he's just innocently dumb. The meta-Smolin is switching in between both of them, trying to make you believe that both Smolins are separately honest, so the meta-Smolin which is their union is honest as well. But this meta-Smolin is not honest because he's logically inconsistent.