Grey, not quite Black

31 Jan 2014

AQt ... we are told black holes are real, and they have a picture of one - a mass accreting black hole is a lumimous gas rich area at the heart of galaxies, and most common in merging galaxies (where lots of material are being gobbled up). The image is an infra red observation.

In spite of all this mainstream hype it is clear that even this black hole is not conforming to the theory. Only a small fraction of merging galaxies show active black holes - or areas of energetic activity. They are, in other words, the exception to the rule. In this paper, the Japanese, enormously fond of black holes, present an explanation for all this - but even they admit only some galaxies display black hole behaviour.

This brings us directly into the big deal this week. Stephen Hawking has said, 'there are no black holes ...' or words to that effect, eagerly pounced on by the media - see ... and the preprint edition is at (2014). Actually, he didn't really say there were no black holes, only that they are not quite what we think they are. They are in effect, a sort of grey. The black surrounding the hypothetical holes is basically a means to thwart light and gas from escaping. It is what you might call a 'firewall' - as in a computer programme designed to block out unwanted hackers and viruses. As no light or gas could escape out of the black and then the hole had to munch its way through all the material that came by, or were attracted to the centre of the galaxy, creating a solid core that is theorised to be extremely dense in nature (and so on, as mainstream has been saying for many a year). Stephen Hawking's version of black holes was challenged by an American astrophysicist, hence the paper above is Hawking's reply, his explanation. This revolves around what is called the 'event horizon' (the black firewall), an invisible boundary beyond which nothing, not even light, can escape. Instead, the boundary, he thinks, only temporarily holds matter and energy, a sort of prisoning, and then releases them. Whereas black holes are wedded to Classic theory, its rival, Quantum theory, enables energy to escape from a black hole - so how do you reconcile the two. Hawking removes the event horizon - simples.

Well, not so simples - black has become grey. At ... we have that headline and that very point, 'Grey is the new black hole: is Hawking right?' - which is a silly question to confront the mathematically challenged or indeed anyone not in the favoured small group dabbling in such theatre. All Hawking has done is provide a mechanism to explain the criticism levelled at his previous papers on black holes. He has shifted the boundary (the firewall, if you like) and turned it into an open boundary, where light and gases are able to come and go (uniting Classic and Quantum theory in the process). Or that is the general idea. This last article is the one to read as it is easier to grasp what the argument is about., whereas the Nature article is a bit confusing (in some ways).

You might also like to read the comments - which are nerdish. Know your scientist - inside and out.