Monday, 16 December 2013

Gravity: from Newton to Einstein and beyond!

by Daniel Rollins

Dr Kazuya Koyama is a Reader in Cosmology in the Institute of Cosmology and Gravitation (ICG) at the University of Portsmouth. His research interests lie in theoretical cosmology, particularly the origin of structure in our Universe and the late time acceleration of the Universe. He gave a talk on the 2nd of December in the DRT on his work on gravity, giving us a tour of the different theories of gravity and their faults, from Newton though to Einstein and finally his own theory of modified gravity compared to ideas about dark energy.

After his talk Sampad Sengupta and I interviewed him about his background, the next generation of physicists, the future of research, and philosophy and its place with science:

Sampad: What led you to study physics and the stars?
Dr Kazuya Koyama: When I was young I was interested in the universe and I wanted to study cosmology and I watched a TV program called the cosmos made by Carl Sagan. I think the primary school teacher showed us this video and I was very interested in in and since then I really wanted to study the universe. I first really studied philosophy because philosophy is one way to understand the universe, then I suddenly realised I needed physics to understand the universe. So I then decided to study physics at university, in fact I started to study physics at university, I didn't’t study physics at A Level or the equivalent in Japan. But then after that I was convinced that physics is a way to understand the universe.
S: What fields of physics are you associated with at the moment?
KK: Basically I am doing cosmology but my theory is based on particle physics, so many ideas are coming from particle physics. So particle physics is looking at a very small object but the theory of particle physics is the basis of the understanding of the universe. So I learn a lot from particle physics.
Dan: With extra dimensions and that sort of thing?
KK: Yes
S: You meet a lot of interns and students from universities across the UK, what do you think of the current generation of physicists? Do you find something different in them which they can develop in the future, can you see a spark?
KK: I don’t think there is much difference. I don’t really see a difference; I sometimes notice that the mathematical training is not so great compared to in the past. (Laughs) But that is how it is always; people always complain about the younger generation but other than that I don’t see much difference.
D: How do you feel about the direction of research at the ICG? Do you like where it is going, do you have any ideas where in 10-15 years research might be?
KK: In ten years we have this exciting new survey so I am interested in finding my own theory of gravity by then and I want to test my theory using that data. An exciting thing is that we can now test my gravitational theory using actual data so that will happen in the next ten years time, I feel that is really exciting. We will be able to test gravitational theory using cosmological data. This is completely new field in cosmology. This will happen in ten years time and in this it is very important to have a close connection between theorist and observers. The ICG is a very special place where we work together, there are a lot of good institutes having good observers, good theorists but they are basically separated and don’t talk. But in the ICG we are on the same corridor we talk every day that is very important and I think this corroboration between theory and observers can bring a very interesting future to cosmology.
D: How about cosmology in general, where do you think the next big idea or question is coming from?
KK: Well I think we already have enough questions, now is the time to answer them. In terms of dark matter it is probably not cosmology, but with particle physics we may be able to answer the question of the origin of dark matter. When we can detect dark matter, it is no longer dark matter. This may happen in ten years time so that is very exciting. It is very good for cosmology as if dark matter is not dark it is just unusual matter. So then we have to think about dark energy. This is very difficult and I’m not sure we can solve this in ten years time but that’s a good thing! (Laughs) We need to have a program!
D: You need a job!
KK: Exactly! So I think dark energy will be the focus of cosmology. My interest is again whether this is dark energy or modification of gravity.
S: To finish off: you stared by saying  you started in philosophy and then turned to physics as it was the tool you choose to answer the questions you had but at what point do philosophy and physics combine and how much do assumptions govern modern physics?
KK: That’s a very interesting question. At the moment for me philosophy and physics are to separate things it is very difficult to unify. But things like cosmological principle and think about Einstein and the idea of static universe, that comes from philosophy, there is no physical reason to believe that the universe is static so there is some prejudice in my mind coming from philosophy and that is very interesting to understand, why we have assumptions in our minds to me in the end it is a separate thing. It is very difficult to unify them. That is the reason why I didn't study philosophy.
D: So you think there is a use for philosophy to almost deconstruct the assumptions we make?
KK: Exactly, that is right, that is right.
S: Well thank you very much; it’s been great interviewing you.
KK: Thank you very much as well.

1 comment:

  1. Thanks, this is really inspiring!

    ReplyDelete

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