MINIATURE BLACK HOLE

These so-called mini black holes, like the more massive variety, lose mass over time through Hawking radiation and disappear. If certain theories of the universe that require extra dimensions are correct, the Large Hadron Collider could produce significant numbers of mini black holes.

An accretion disk forms whenever the matter being accreted possesses enough rotational or angular momentum that it cannot simply fall inward toward the accretor along a straight line. In directions perpendicular to the accretor’s rotation axis, the flow tends to flatten onto a disk because the rotation resists the inflow of the material. In directions parallel to the rotation axis, the matter contracts toward a plane until the thermal pressure inside the disk roughly equals the gravitational force.

So what would these tiny black holes be like? Should we be worried about them?

Cigdem tells me: ‘According to Stephen Hawking, they will not be that black in fact. They will evaporate with time approximately following a black body radiation spectrum. The evaporation rate will be inversely proportional to the black hole mass.’

‘Astronomical black holes are so massive that their evaporation rate is negligible. In contrast, mini black holes are hot: unimaginably hot. The core of our Sun is at around 15,000,000 degrees Kelvin - to get close to the temperature of a mini black hole you would need to add another 42 zeroes.’

‘What this incredible temperature means is that mini black holes of tiny mass ‘evaporate’ into the far, far colder space around them almost infinitely fast. Their expected lifetime is around one octillionth of a nanosecond – so that they pop out of existence again almost as soon as they are created.’If they do appear they will almost instantaneously burst into many particles which the ATLAS detector should pick up.These particles will have very striking features. The total energy deposited in the detector will be of the order of a few TeVs [Tera electron volts] and the number of final state particles will be large. Black hole signatures can hardly be imitated by any other new physics so, if they are being produced, it will be hard to miss them,’ Cigdem adds.So the hunt begins: on 30 March the LHC is aiming for collision energies of 7 TeV that may enable us to see some quantum gravity effects for the first time.

At the beginning of this year Dr Cigdem Issever moved to CERN to coordinate the efforts of the ATLAS Exotics physics group.Read more about this topic in What black holes can teach us by Sabine Hossenfelder and the LHC Safety Assessment Group report.

                           J.Loshini(2213721033015)