Monday, August 16, 2010

A New Generation Of Copenhagen Interpretations.

In 1927, Neils Bohr and others formulated what became known as the Copenhagen interpretation of quantum mechanics, in Copenhagen Denmark.  This week I am attending a workshop in Copenhagen at the Neils Bohr Institute on that same ground that attracted so many famous physicists so long ago.

It's also interesting to reflect how far quantum mechanics has come.  In 1927 physicists were still trying to formulate what kind of theory quantum mechanics even is.  Today, the workshop began with with a talk entitled "The Quantum Origin of the Universe."  We've gone from formulating a new physical theory to explaining the whole structure of the universe with it in less then a century!!!  

There were 3 main talks today and I summarize briefly:

Viatcheslav Mukhanov:  Gave the talk about the quantum origins of the universe.  He emphasized the importance of inflation and claimed all objections to inflation are now really starting to look silly.  People either attack a mechanism of inflation ("Dude, I don't like inflation cuz it is some ad hoc scalar field...") showing their ignorance not understanding that the effects of the theory are mechanism independent. (Example: you get primordial density perturbations no matter what the mechanism.)  Or, they come up with some metaphysical argument why they don't like inflation.  (How dumb would I look if I gave a philosophical argument why I don't think it makes sense that the Earth orbits the sun even though we see it in experiment?)

At this point he quoted a the physicist Nobel Laureate Steven Weinberg who said (discussing cosmology):
Our mistake is not that we take our theories too seriously, but that we do not take them seriously enough. It is always hard to realise that these numbers and equations that we play with at our desks have something to do with the real world.
Always remember that quote!

Anupam Mazumdar:  Talked about two things, first emphasized how much progress had been made showing inflation really does recover low energy physics and the second half talked about how gravitational waves, if detected, could revolutionize the field.  The stuff on gravity was was very interesting.

Alan Heavens: Discussed what we will learn about the universe from gravitational lensing over the next decade or so. It was very interesting.  Right now you are used to seeing pictures of stars and galaxies.  Fine, but with gravitational lensing, in the future, we will be able to map out the 3D structure of the Dark matter Halos stars and galaxies sit in.    Furthermore, the 3D lensing reconstruction will test aspects of cosmology in all new ways and will be become a very stringent test on General Relativity. (For instance, it may be cosmologists using lensing who discover the hierarchy structure of the neutrino masses!)


  1. Just think what R. Gary and the boys would make of quantum origins of the Universe. Though it wouldn't surprise me if an obscure lesson manual reference was produced. =:)

  2. Stan,

    Unfortunately some people always feel threatened when we learn something new about nature. Centuries ago people threw a fit when scientists suggested the earth orbited the sun. History has a way of repeating itself.

    But don't worry, those who embrace truth always receive more, which is why history is proof that those who accept scientific advances go on to make more useful scientific advances. So we have a lot to look forward to!!! And those who reject the the advances... well they become the next unfortunate generation of people who reject things like the earth is round.

    Rejecting truth surely has a damning effect doesn't it?

  3. I did use some quotations of Niels Bohr on my blog about atom (chemistry part, Saturday, September 26, 2009 ), may be this can help.

  4. Joe,

    I don't think anybody seriously argues against inflation so much as it makes people nervous. It's like flying on a plane if you've never in your life seen a pilot - you're pretty sure there must be somebody driving the plane, but it would make you feel a lot better if you know what a pilot was.

    When you demand the existence of something that you have no other evidence for, it's unsettling - not wrong, but unsettling.

  5. Nick,

    I appreciate the plane analogy.

    But just to be clear, there is plenty of evidence that the universe went through a phase of cosmic acceleration which is by definition what inflation is. What drove the acceleration is still beyond us, (Though there is reason to believe one day we may know for sure), but we are sure the acceleration happend.

    Is there any physical phenomena that goes on in the Sun that we know happens but aren't 100% sure what drives it? Does not knowing the mechanism that drives the phenomena make you doubt whether the phenomena that you are measuring is happening or not?

    If somebody dies but the cause of death is unknown should that cause me to question if the person is really dead?

    Such is the case with inflation. We are sure the acceleration happend and thus inflation is real. Who is the culprit is in question, but one day we will hopefully have that pinned down as well.


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