Sam Wormley
2015-11-29 02:55:29 UTC
CERN collides heavy nuclei at new record high energy
How bad would it be if we accidentally made a black hole?
http://phys.org/news/2015-11-cern-collides-heavy-nuclei-high.html
"The collision energy between two nuclei reaches 1000 TeV. This
energy is that of a bumblebee hitting us on the cheek on a summer
day. But the energy is concentrated in a volume that is approximately
10^-27 (a billion-billion-billion) times smaller. The energy
concentration (density) is therefore tremendous and has never been
realised before under terrestrial conditions," explains Jens Jørgen
Gaardhøje, professor at the Niels Bohr Institute at the University of
Copenhagen and head of the Danish research group within the ALICE
experiment at CERN.
Related Article:"The collision energy between two nuclei reaches 1000 TeV. This
energy is that of a bumblebee hitting us on the cheek on a summer
day. But the energy is concentrated in a volume that is approximately
10^-27 (a billion-billion-billion) times smaller. The energy
concentration (density) is therefore tremendous and has never been
realised before under terrestrial conditions," explains Jens Jørgen
Gaardhøje, professor at the Niels Bohr Institute at the University of
Copenhagen and head of the Danish research group within the ALICE
experiment at CERN.
How bad would it be if we accidentally made a black hole?
http://www.askamathematician.com/2015/11/q-how-bad-would-it-be-if-we-accidentally-made-a-black-hole/
Physicist: Not too bad! Any black hole that humanity might ever
create is very unlikely to harm anyone who doesn’t try to eat it.
they eat and they pop. For the black holes we might reasonably
create on Earth, neither of these is a problem.
To create a new black hole here on Earth, we’d probably use a
particle accelerator to slam particles together and (fingers crossed)
get the density of energy and matter in one extremely small region
high enough to collapse. This is wildly unreasonable. But even if
we managed to pull it off, the resulting black hole wouldn’t suddenly
start pulling things in any more than the original matter and energy
did.
For comparison, if you were to collapse Mt. Everest into a black hole
it would be no more than a few atoms across. It’s gravity would be
as strong as the gravity on Earth’s surface within around 10 meters.
If you stood right next to it you’d be in trouble, but you wouldn’t
fall in if you gave it a wide berth. In fact, that’s why mountain
climbers aren’t particularly bothered by Everest’s mass; even if
you’re literally standing on it, you can’t get within more than a few
km of most of its mass (fundamentally, Mt. Everest is a big, spread
out, pile of stuff).
But the amount of material used in particle accelerators (or any
laboratory for that matter) is substantially less than the mass of
Everest. They’re “particle accelerators” after all, not
“really-big-piles-of-stuff accelerators”. The proton beams at the
LHC have a mass of about 0.5 nanograms and when moving at full speed
have a “relativistic mass” of about 4 micrograms (because they carry
about 7500 times as much kinetic energy as mass). 4 micrograms
doesn’t have a scary amount of gravity, and if you turn that into a
black hole, it still doesn’t. A black hole that small probably
wouldn’t even be able to eat individual atoms. “Probably” because
we’ve never seen a black hole anywhere near that small.
Physicist: Not too bad! Any black hole that humanity might ever
create is very unlikely to harm anyone who doesn’t try to eat it.
they eat and they pop. For the black holes we might reasonably
create on Earth, neither of these is a problem.
To create a new black hole here on Earth, we’d probably use a
particle accelerator to slam particles together and (fingers crossed)
get the density of energy and matter in one extremely small region
high enough to collapse. This is wildly unreasonable. But even if
we managed to pull it off, the resulting black hole wouldn’t suddenly
start pulling things in any more than the original matter and energy
did.
For comparison, if you were to collapse Mt. Everest into a black hole
it would be no more than a few atoms across. It’s gravity would be
as strong as the gravity on Earth’s surface within around 10 meters.
If you stood right next to it you’d be in trouble, but you wouldn’t
fall in if you gave it a wide berth. In fact, that’s why mountain
climbers aren’t particularly bothered by Everest’s mass; even if
you’re literally standing on it, you can’t get within more than a few
km of most of its mass (fundamentally, Mt. Everest is a big, spread
out, pile of stuff).
But the amount of material used in particle accelerators (or any
laboratory for that matter) is substantially less than the mass of
Everest. They’re “particle accelerators” after all, not
“really-big-piles-of-stuff accelerators”. The proton beams at the
LHC have a mass of about 0.5 nanograms and when moving at full speed
have a “relativistic mass” of about 4 micrograms (because they carry
about 7500 times as much kinetic energy as mass). 4 micrograms
doesn’t have a scary amount of gravity, and if you turn that into a
black hole, it still doesn’t. A black hole that small probably
wouldn’t even be able to eat individual atoms. “Probably” because
we’ve never seen a black hole anywhere near that small.
--
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sci.physics is an unmoderated newsgroup dedicated
to the discussion of physics, news from the physics
community, and physics-related social issues.