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Why is the universe just right for us?

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by Marcus Chown

Lucky to be here (Image: amorrisphotography.com/Getty)

IT HAS been called the Goldilocks paradox. If the strong nuclear force which glues atomic nuclei together were only a few per cent stronger than it is, stars like the sun would exhaust their hydrogen fuel in less than a second. Our sun would have exploded long ago and there would be no life on Earth. If the weak nuclear force were a few per cent weaker, the heavy elements that make up most of our world wouldn’t be here, and neither would you.

If gravity were a little weaker than it is, it would never have been able to crush the core of the sun sufficiently to ignite the nuclear reactions that create sunlight; a little stronger and, again, the sun would have burned all of its fuel billions of years ago. Once again, we could never have arisen.

Such instances of the fine-tuning of the laws of physics seem to abound. Many of the essential parameters of nature – the strengths of fundamental forces and the masses of fundamental particles – seem fixed at values that are “just right” for life to emerge. A whisker either way and we would not be here. It is as if the universe was made for us.

What are we to make of this? One possibility is that the universe was fine-tuned by a supreme being – God. Although many people like this explanation, scientists see no evidence that a supernatural entity is orchestrating the cosmos. The known laws of physics can explain the existence of the universe that we observe. To paraphrase astronomer Pierre-Simon Laplace when asked by Napoleon why his book Mécanique Céleste did not mention the creator: we have no need of that hypothesis.

Another possibility is that it simply couldn’t be any other way. We find ourselves in a universe ruled by laws compatible with life because, well, how could we not?

This could seem to imply that our existence is an incredible slice of luck – of all the universes that could have existed, we got one capable of supporting intelligent life. But most physicists don’t see it that way…. Read the rest of this entry »

Written by physicsgg

July 29, 2011 at 6:26 pm

Posted in COSMOLOGY, philosophy

Are quarks real? A philosphical Interlude.

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The reality of things is a serious matter. But not too serious, says Michael Krämer
The Nobel-Prizewinning physicist and sometime bongo-player Richard Feynman famously said
“Philosophy of science is about as useful to scientists as ornithology is to birds”.
I have actually always liked philosophy. As a physics undergraduate I regularly attended philosophy seminars and lectures. Later during my PhD in elementary particle physics at the national laboratory DESY, in Hamburg, I often got together with students from all kinds of backgrounds to drink wine and discuss philosophy. While I can’t remember what kind of books we read and talked about, I always enjoyed the debates, especially the different points of view. Unfortunately, while pursuing a career in particle physics, I lost touch with philosophy. However two years ago my colleague and friend Robert Harlander told me about a working group on particle physics, philosophy and history which had formed in Wuppertal.
Robert invited me to one of the meetings, and I was very impressed how the group interacted and worked jointly on various topics at the interface of LHC physics, philosophy of science and contemporary history of science. Recently, the Wuppertal group organized an international spring school on particle physics and philosophy, which I found very exciting and enjoyable. It included a mixture of lectures by physicists, philosophers and historians, as well as working groups where students debated topics like the “theory–ladenness of experiments” and the “reality of quarks”. Everybody was very enthusiastic, and the talks and tutorials triggered plenty of discussion between lecturers and students. There was a good feel about the school, with some memorable late night conversations, where I learned about the role of shoes in Heidegger’s philosophy, Berlin’s street art scene, and the magic of the Bergisches Land.

Murray Gell-Mann, captain quark, by Toyah Walker, from Lily's quarks.

Back to philosophy! Paul Hoyningen-Huene from Hannover presented a stimulating introductory lecture on positions and limits of physical knowledge….. Read the rest of this entry »

Written by physicsgg

June 17, 2011 at 7:10 am