"God particle" close at hand?

Response to Boom Boom's "Oh Lord"
As gospel luminary Albert E. (Sheila's Dad) put it, "E=mc2 + please don't let me be misunderstood..."

[ 08 April 2008: Message edited by: martin dufresne ]

And Rush Limbaugh [url=http://www.rushlimbaugh.com/home/daily/site_040808/content/01125112.gues... none too happy about it[/url]

Just in case some of you guys are wondering, there is a lot of consternation in the press about worries this accelerator might produce mini black holes and destroy the Earth.

I can assure you all that this will not happen with complete confidence. This may be the largest human experiment ever conducted, which will as such advance science, but energies 100 million times greater are observed to hit the atmosphere due to cosmic rays. And they don't destroy the Earth. Secondly, even if mini black holes are produced... they would be mini black holes, they would evaporate before travelling anywhere. And even if black holes don't evaporate, they would pass right through the Earth, like neutrinos do.

[ 08 April 2008: Message edited by: 500_Apples ]

quote:

---

Originally posted by jrootham:
[b]No, I don't expect there to be a disaster. However, I don't think I'd be quite as sanguine about black holes as all that. The evaporation part is good, and a good thing too. The gravity gradient around a black hole would seem to make it very unlikely that it would be quite as non interacting as neutrinos.

What happens if the black hole takes up an orbit that intersects the earth and gathers mass on its journey?[/b]

---

jrootham,

First of all, "gravity gradients" don't matter, all that matters is gravity. The popular media teaches that black holes are vacuum cleaners, but that's false. If the sun collapsed into a black hole tomorrow, the Earth would keep rotating around the sun in exactly the same manner, however it would freeze due to lack of sunshine.

A mini black hole would not weigh as much as the sun. It would not weight a gram. It would, due to the energies involved at the LHC, it would weigh around 0.00000000001 grams (that number of zeros). As gravity is the weakest force that would not matter. Does dust fall on you (70, 000 grams) because of your gravity? No. Molecules don't care about gravity, they only care about electricity and magnetism, gravity is so much weaker that theorists don't bother to include gravity in their calculations, and they still get the right answer to the limit of experimental precision (12 significant figures).

Neutrinos actually don't interact with the Earth because of gravity, but because of the weak nuclear force, which is much stronger than gravity. A mini black hole would only interact due to the gravity of 0.00000000001 grams, and would as such be non-interacting.

ETA:

It can't take up an orbit and intersect the Earth. Everything produced at the LHC will be going at 99.99...% the speed of light. That's way beyond the Earth's and the Sun's escape velocity.

[ 08 April 2008: Message edited by: 500_Apples ]

That's the big question, isn't it? The main argument in favour of the safety of these experiments is that the energies produced is less than the amount of energy produced when certain cosmic rays strike the upper atmosphere, and these cosmic ray collisions happen all the time but the Earth is still here. For this to go wrong, three things would have to happen:

1. A micro black hole (or something else equally dangerous- see below) would have to be produced by the collision.

2. The micro black hole produced would be moving much slower than the colliding particles (possible in a head on collision) so that its velocity is less than the escape velocity of the Earth, AND

3. Black hole evaporation, as predicted by Hawking, either does not happen or happens slower than he predicts- slowly enough that the black hole would acrete more mass than it loses through evaporation.

Now 3 is perfectly plausible (the basis for Hawking radiation is entirely theoretical at this point, though the idea seems sound enough)... except that given the number of cosmic ray collisions with the upper atmosphere that have occurred it seems unlikely to me that the situation described in 2 would [i]not[/i] have occurred at some point- unless the black holes never appeared in the first place.

Another nasty scenario has been raised- the creation of a stable [url=http://en.wikipedia.org/wiki/Strangelet]strangelet[/url] which could cause matter it contacts to also turn into strangelets. Again, the risk of this seems low, though a caveat exists in that most models for cosmic ray collisions producing strangelets involve positively charged ones which (it is hoped) would be prevented from colliding with nuclei by repulsion, but that some particle accelerator experiments might produce negatively charged strangelets, with drastically different results.

In any case, apparently no evidence of strangelets has been found in either accelerators or cosmic ray collisions, so I'm not too worried about this.

quote:

---

Originally posted by Proaxiom:
[b]

As a non-expert who reads some science blogs, I have been led to think that the hypothesis that a micro black hole could possibly be created by such an experiment is strongly linked to the hypothesis that Hawking radiation exists, and therefore we are likely to get both or neither, which makes us safe either way.[/b]

---

Hawking radiation is standard physics, quantum mechanics and stat mech and GR.

Mini black holes are General Relativity... but not at these energies. There's an estimated 10% chance of seeing them if theories of extra dimensions are true.

ETA: you can still get mini black holes from particles accelerators in known rather than speculative physics, but you'd need much, much, much higher energies than 7 Terra-ElectronVolts.

[ 08 April 2008: Message edited by: 500_Apples ]