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To explain quantum effects in classical gravitational fields is still a challenge. For example, we do not know how Hawking radiation back-reacts on the curved space-time. An even more basic question to ask is: Does Hawking radiation really exist? The definable proof would be to measure it.
But, unfortunately - from an experimental point of view - black holes are not seen in our stellar neighborhood. In addition, the radiation from a stellar mass black hole (10 micro Kelvin) is much colder then the CMB (3 Kelvin).
It is even worse, once we realize that we do not have any direct experimental evidence for quantum field theory in curved space-time at all.
It would be great to have "something" to play around with - a quantum field imbedded in a curved space-time - without facing all these problems. From a theoretical point of view, it should be a system we know very well, so that we obtain "quick" answers. And even more important, there should be a realistic chance to verify (measure) the theoretical predictions!
We do have this "something", the analogue (analog) models. There are many systems known that can be used as analogue models. The ones I am particularly interested in are fluids and super fluids. To be more precise I focus on BEC (Bose-Einstein condensate) based analogue models, because it seems - from a personal point of view - the most promising for both experimental and theoretical advances.
I have met many people who were asking: How deep is the analogy between real and analogue gravity? The answer is very simple: Given the fact that you trust the calculations from real gravity, then it depends if you consider quantum field theory in external fields as an established theory, or not. If so, the two things must have the same properties.

	To explain quantum effects in classical gravitational fields is still a challenge. For example, we do not know how Hawking radiation back-reacts on the curved space-time. An even more basic question to ask is: Does Hawking radiation really exist? The definable proof would be to measure it. But, unfortunately - from an experimental point of view - black holes are not seen in our stellar neighborhood. In addition, the radiation from a stellar mass black hole (10 micro Kelvin) is much colder then the CMB (3 Kelvin). It is even worse, once we realize that we do not have any direct experimental evidence for quantum field theory in curved space-time at all. It would be great to have "something" to play around with - a quantum field imbedded in a curved space-time - without facing all these problems. From a theoretical point of view, it should be a system we know very well, so that we obtain "quick" answers. And even more important, there should be a realistic chance to verify (measure) the theoretical predictions! We do have this "something", the analogue (analog) models. There are many systems known that can be used as analogue models. The ones I am particularly interested in are fluids and super fluids. To be more precise I focus on BEC (Bose-Einstein condensate) based analogue models, because it seems - from a personal point of view - the most promising for both experimental and theoretical advances. I have met many people who were asking: How deep is the analogy between real and analogue gravity? The answer is very simple: Given the fact that you trust the calculations from real gravity, then it depends if you consider quantum field theory in external fields as an established theory, or not. If so, the two things must have the same properties.

	Beside the analogue models I am also involved in some other projects dealing with real gravity, for example together with Matt and Petarpa I am working on a way how to generate and classify perfect fluid sphere solutions. Have a look at Petarpa's research interests: Petarpas website.