New Safety Arguments Expected From LSAG
Here James Blodgett is debating with a physicist from CERN on the topics which are assumed to be the focus of the soon-to-be-released LSAG safety report:
I say:
Relativistic strangelets are torn apart when they hit a neutron star, or a planet, and are converted into normal matter.
You answer:
There is nothing whatsoever in physics that would make this happen. It doesn’t matter whether or not the strangelet is “relativistic”, because it is only relativistic relative to some frames of reference. The entire point of the strangelet is that it is more stable (theoretically) than ordinary matter, and hence would never be reconverted. So this counter-argument is not sensible.
Here is what the RHIC safety study has to say about it:
strangelets produced with even relatively low rapidity in the lunar rest frame do not survive subsequent collisions with nuclei in the lunar soil. [from W. Busza, R.L. Jaffe, J. Sandweiss, and F. Wilczek; "Review of Speculative ‘Disaster Scenarios' Brookhaven, 2000, p.22.]
“Not surviving collisions with nuclei” is what I mean when I say they are “torn apart”. Busza et al say that this happens even with relatively low rapidity, so I assume that it will also happen with high rapidity. I suppose that you could be correct and the Busza paper wrong. However, in the face of a citation like this, you need to provide better evidence for your assertion. Until that time, I classify your assertion as not yet demonstrated.
You say:
One piece of information: The escape velocity of a neutron star is a very large speed, already relativistic (something around 50% of the speed of light).
Okay, but consider a micro black hole (of any velocity) about to enter a neutron star from well outside. In this position, it has all of the potential energy of a fall from well outside to the center. That is exactly the energy required to carry it to the symmetrical point on the other side of the star. This is in addition to the energy of its intrinsic velocity. So (assuming no collisions) when it gets out of the star it still has the velocity it had when it entered. This is basically true whatever the escape velocity (until an event horizon forms). The exit arm of a hyperbola of a comet rounding a star looks exactly the same as the entrance arm. In the case of a black hole it can dip into the star and still get a similar hyperbola. Also note my assertion that almost all black holes will be relativistic, so the velocity when they get out is still relativistic.
The other case is when a cosmic ray hits a neutron star particle and forms a micro black hole. In this case I assert that the micro black hole will always be relativistic and I conjecture that it will always exit the neutron star. It might be possible to show calculations that prove me wrong.
You say that a neutron star is dense. You also say:
If black holes interact so weakly that they would pass through a neutron star unaffected (more or less) then they pose no threat to us, even if they are stable.
Regarding density, I understand that the collision of consequence is the collision with the quarks. Even at nuclear density, quarks are widely spaced. A neutrino can traverse a light year of lead. I conjecture that a neutrino (or a micro black hole) can traverse a few kilometers of neutronium. A micro black hole is even more likely to traverse, since when it hits a particle it accretes and slows slightly rather than stopping. I could be wrong. I await calculations that show that I am wrong. I await calculations that prove your point about neutron-star-traversing black holes posing no threat.
It is appropriate that I ask for calculations. By the precautionary principle, it is up to advocates of a dangerous activity (i.e. you) to prove that it is safe. This is not just tree-hugger anti-science philosophy. It makes sense in most plausible risk contexts. Consider the opposite. Consider that opponents have to prove that an activity is dangerous by the standards of normal science, the standards required for publication. Now suppose that I have a reasonable reason to question the safety of a passenger airplane. Suppose even that an evaluation of data suggests a 20% chance that the data shows that the airplane will crash. I have not proved that the airplane will crash by the standards of statistical significance. Therefore should the airplane be approved for flight? Do you want to ride on that airplane? The precautionary principle is accepted by risk experts, and I think we should accept it here. So the burden of proof is on you (or CERN).
You say that the LSAG report will develop limits on how fast a micro black hole can accrete based on neutron star considerations. I agree that this could be a productive approach. However, this still leaves us waiting for the LSAG report. (I’ll bet we get no more than a month or two to evaluate that report before LSAG startup, and no official avenue for objections if we find valid reasons to object.) I have asserted that a black hole would almost never remain in a neutron star, and you have not yet shown that I am wrong. You conjecture that a black hole that can traverse a neutron star accretes so slowly that it is no threat. This could be true but it is not yet demonstrated. There are a bunch of models for black hole accretion. They vary by orders of magnitude in the time to swallow Earth. I very much hope that the LSAG considers all of these models, demonstrates that the models are exhaustive, and refutes all of the fast ones.