Finding Fred & friends
Posted: May 20, 2011 Filed under: Uncategorized | Tags: black hole, gamma ray burst, white hole 1 Comment“What’s your name?” Kit said. “I mean we can’t just call you ‘hey you’ all the time.”
True, the white hole said. My name is Khairelikoblepharehglukumeilichephreidosd’enagouni – and at the same time he went flickering through a pattern of colours that was evidently the visual translation.
“Ky-elik-” Nita began.
“Fred”, Kit said quickly. “Well”, he added as they looked at him again, “if we have to yell for help or something, the other way’s too long.”
Fred, whilst being in many ways not a typical white hole (he talks for a start, and is surprisingly prone to hiccups), does exhibit their most fundamental property – he continuously emits stuff.
A white hole is a region of space and time which can’t be entered, but which gives out material. It’s the opposite of a black hole, we’ve never seen one and there’s a good chance they don’t exist. The possibility that they do arises from the maths of Einstein’s General Relativity. Even if they do, the combination of a strong gravitational pull and the constant stream of new material being emitted means that they’ll probably collapse in on themselves and form a black hole before we could see them.
Hang on though, what if they just popped into being for an instant, spewed out a load of stuff at once, and then vanished again? That’s the idea put forward in a paper which came out this week. The authors suggest that if this was the case they could pop up anywhere in the Universe, and we’d see them as brief, intensely bright, objects. This sounds suspiciously like the features of a mysterious type of object called a gamma ray burst.
The current best explanation for the majority of gamma ray bursts is the explosion of a massive star. However, there exists a subset of sources which don’t fit this picture, and it is these which might, just might, just possibly be white holes. The chances that any of them are like Fred though are, sadly, small.
Alon Retter, & Shlomo Heller (2011). The Revival of White Holes as Small Bangs Submitted to ApJ arXiv: 1105.2776v1
In a Bose–Einstein condensate no one can hear you scream!
Posted: June 18, 2009 Filed under: Uncategorized | Tags: black hole, Bose-Einstein condensate, gravity, quantum mechanics, sound 1 Comment[tweetmeme only_single=false service=”wp.me” source=”allinthegutter”]
ok perhaps not as catchy as “in space no one can hear you scream!” but its a pretty apt description of the work of a number of condensed matter physisits who have recent created the worlds first acoustic black hole. Now I know what you are thinking … it was the same thought I had as soon as I heard about this work : acoustic black hole + coldplay = a better world for us all. In my head its like those flying flat prison things from superman … but we let out the brutal superhuman dictator and replace him with the far greater evil of coldplay
Seriously though this is some really cool stuff. As we all know in our current theory of gravity, matter and energy bend space and time around it and in turn light and matter will move along the contours of this curvature. In a black hole the density of the matter/energy doing the warping of space time is so great that light (and everything else) is unable to escape from that region. Now what you might not have known (I certainly didn’t!) is that it turns out that in a certain state of matter, known as a Bose-Einstein condensate, the equations which govern the paths of sound through the matter are the same as those which govern how light travels along the curvature of space. This throws up an pretty intriguing idea: could we create within a Bose-Einstein condensate a region from which no sound can escape? A form of coldplay prison acoustic black hole?
Well it turns out that not only is the answer a resounding “hell yeah!” but some scientists form the Israel Institute of Technology, in Haifa have done just that. They created a region within the Bose-Einstein condensate which had a supersonic flow, that is the material which makes up the condensate is moving faster than sound. Within this region little packets of sound called phonons (an analogous version of photons but for sound instead of light) can never escape this region. Its sort of like running on one of those flat escalators that you get at airports, if its moving faster than you can run you can never get off it. The border between the supersonic region and the rest of the condensate then acts like an event horizon in regular black holes.
we are all in the gutter 