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Professor Carlos Frenk

Professor Carlos Frenk is a cosmologist who won the Gold Medal of the Royal Astronomical Society in 2014.  His research is in the fields of cosmology, galaxy formation and computer simulations of cosmic structure formation.  he is the current Director of the Institute for Computational Cosmology at Durham University in the UK, where he builds model universes in state of the art computers.


 I was always much too curious when I was a young fellow


On earliest memories of science

Yeah, I was a nuisance, I was always much too curious when I was a young fellow; I wanted to be a mathematician or a physicist and my mother said, you’re never going to earn your living being a physicist, so I ended up studying engineering for one term, and at the end of one term the professor called me up and said, you know, you're in the wrong place, why am I in the wrong place?  Because you ask too many questions.  Engineering is not about why, it’s about how, why don’t you go and do physics and be a happy man. 


So that’s what it was, I was just too inquisitive and too curious and I wanted to - from a young age - figure out how things worked, not in an engineering sense, but in a general sense.


I think one of the great lessons we've learned in the history of physics over the last 300 years, every time you answer a fundamental question, many more equally or even more fundamental questions crop up so that’s why…people who talk about theories of everything, I think they're barking up the wrong tree, there is no theory of everything, the universe is, as far as I can see, unlimited in the mysteries it has and so I think being a scientist is tremendous because there’s no end.  There’s a down side, of course, because you don’t have a nine to five job and just like the universe is full of questions that are unanswered, so is your day, there’s never an end to your work.


On The Big Bang

Well, the Big Bang itself, the Big Bang is a theory that tells us that the universe as we know it began in a state of extremely high density and temperature.  However, if you actually look at the equations in physics that describe this state, they actually blow up because in reality the density and temperature of the universe in early times was not just very large, it’s infinite, and our equations cannot entertain infinity so the questions of relativity blow up.  We know why they blow up and that is because the theory of relativity explains, tells us about gravity, tells us about the universe, but when the density of the universe is so high that, say, it is like the density of an atom, then clearly we need also to have quantum phenomena to take those into account.  Now they're described by quantum theory and quantum physics, but relativity and quantum physics are independent, separate theories, we do not have a theory that simultaneously explains relativity and quantum phenomena so we don't really know, to be honest, much about the Big Bang because that theory breaks up, or breaks down, or both actually because when they break up and blow up.  


So we have this thing, which is now part of the Big Bang theory, called inflation.  Inflation is a phenomenon that began very soon after the Big Bang, a fraction of a second after the Big Bang: 10 to the minus 35 seconds or so after the Big Bang.  Now inflation is a phenomenon for which we have increasing empirical observational evidence and inflation is associated with quantum processes, it’s not quite quantum gravity but it is associated with quantum phenomena.  Now quantum processes are characterised by fluctuations, so the idea of inflation is that very early on the universe had something we called vacuum energy, which is some energy we associate with quantum phenomena, and these quantum phenomena were fluctuated and that in fact was eventually the source of galaxies and things we see in the universe today.  But as the universe inflates, these perturbations, these quantum fluctuations, could very easily get some patch of universe to undergo a big bang itself, and so in this idea known as eternal inflation…in fact, quantum processes produce a very large number of universes, which for all intents and purposes is an infinite number of universes, so this is a slightly disturbing concept, it’s disturbing for many reasons, one is our brains are not really attuned to deal with infinities, but we get used to these things eventually, but it’s disturbing from that point of view.  It’s also disturbing because in a sense it goes beyond really what we understand by physics, because these other parts of the multiverse, if we live in a such an entity in this multiverse, these other elements in the multiverse, these big bangs, are never accessible to us, they're beyond what we call our horizon so you would need to travel much, much, much, much faster than the speed of light in order to have any communication with them.  So, in this sense, the multiverse is kind of outside the envelope of physics but it seems to me - and it seems to a lot of other people - an inevitable consequence, that if inflation happened, then a large number - an infinite number - of universes would've gone bang.  Good for them, they're somewhere out there, we’ll never know much about them, so me as an astrophysicist, I’m perfectly content with the universe that we know, I think its a wonderful universe full of amazing phenomena and most of my time - literally all of my time - I worry about that universe, I don’t worry too much about the multiverse. 


On evidence of the Big Bang

Actually, a fossil is a very good analogy because we do have a fossil in the universe which we call the relic radiation or the fossil radiation, and that is the radiation that came from the Big Bang itself.  So when the universe was about 380,000 years old, a small fraction of 13.7 billion years - in fact it’s the human equivalent to one day in the life of the universe - an important phenomenon happened, the heat of the Big Bang was liberated because the early phases of the Big Bang were foggy, at this point the fog lifted and the radiation of the Big Bang was able to propagate freely until we detected it in our telescopes. Now that radiation brings us news about what was going on in the universe in the one day equivalent, human equivalent, 380,000 years after the Big Bang.  That sounds like a long way from the 10 to the minus 35 seconds, indeed it is, however at 10 to the minus 35 seconds, the theory of inflation makes a number of predictions and one is that these quantum fluctuations which we were talking about would have seeded the universe with small irregularities, and inflation tells you a lot of other properties of these irregularities.  These irregularities grow during the Big Bang, the fireball phase, but they leave an imprint in this radiation and the year.  So when the heat is liberated and we are finally 13.7 billion year later, we measure it in our telescopes, it bears news not only about the universe 380,000 years after the Big Bang but about what happened much earlier when, because of these quantum processes in inflation, small irregularities were imprinted, in fact, in the temperature of the radiation.  So the small hot and cold spots in the temperature in the relic radiation were discovered in 1992 by an experiment called the COBE satellite, the principal investigator who of course got the Nobel prize for this, George Smoot, became very unpopular because he said looking at the map 380,000 years after the Big Bang is like looking at the face of God.  He got a lot of flack for this, it wasn't the face of God, it was the imprint of processes that happened very much earlier on, probably in the epoch of inflation, so that’s how we know, and that’s why many of us are confident that inflation or something like that is a good description of our universe.  That’s just one example, there are other predictions that the theory made, having to do with the geometry of the universe that have come true, and this I think is actually a very good question because it illustrates what physics is all about; in physics, we are allowed to come up with bewildering ideas, it doesn't matter, you still get paid at the end of the month, so long as your ideas are testable.  So long as you can express your hypothesis in a mathematical language and then use the language of mathematics to predict phenomena that have not yet been measured or observed in the laboratory or in nature.  And inflation does just that, it predicted these irregularities, it predicted the geometry of the universe and so that’s why we can have confidence that we know what’s going on in the early life of the universe.


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