The end of physics has been proclaimed several times.  For instance at the end of the 19th century when statistics and mechanics were figured out, some thought it was going to be merely a matter of calculation.  Between Newton and Maxwell they might have figured it all out right?  Except there were very simple problems that defied calculation.  For instance the “lumineferous ether” didn’t seem to exist and the “ultraviolet catastrophe” led to first relativity and secondly to quantum physics both of which Albert Einstein had a hand in.  After general relativity was fleshed out it took from early in the 1900’s up to somewhere around 1965 to finally figure out quantum field theory and what we now call the standard model.

 

But it’s worth looking back at right around 1960-1965.  Just like for Einstein back in the early 1900’s there were enough clues that anyone who looked long and hard enough at the problem would be able to eventually figure it out.  We had something called the “particle zoo” for instance Muons (which are basically heavy electrons) all kinds of mesons (quark + anti-quark, pions, rhos, phi omega).  This zoo of 40 or so “elementary” particles gave rise to all sorts of wild theories, various incarnations of the s-matrix and yes, string theory was invented to try to explain it, but eventually we found out that the strong force worked the same as the electro-weak force, that is the same equations held “all” that changed were the coupling constants.

Between 1965 and today all that has happened is 1) verification and more verification of both relativity and the standard model (like the discovery of the higgs) and 2) discovery of dark energy and dark matter.

But now we face a real problem in physics.  We don’t have the clues we had at the turn of the century that led Einstein to his miracle year nor do we have the clues that we had back in 1960 with the particle zoo.  All we have are very small hints and the real extent of the problem is clear.  To get to the energy levels required to create our own dark matter it seems likely we will need energy levels approaching 1,000,000,000 times more than the LHC.  10^-23cm is right around where both the weak force and dark matter are hiding and to pry them out in the open we would need a new LHC that is larger than the earth.  Right now the LHC is many orders of magnitudes hotter than any star, it’s pretty close to the big bang, but to get to where we think we need to is going to be a problem.   Astronomical physics is also a problem, as the cosmic background radiation doesn’t actually go back to the big bang it only goes back to a few hundred thousand years afterwards when the universe cooled down enough to create atoms because before that the universe was opaque.

What is next then?  The web telescope is 8.7b, 13b for ligo, huge telescopes like SKA and EELT are about 2b, Super-Kamiokande is relatively cheap for a few million, the Kepler telescope was also a bargain and a half billion.  But anywhere we look it seems like it will be a costly search.  And we don’t have any plan forward.  There are as many theories for the dark matter as you might like, though the WIMP seems most likely and supersymmetry also seems like a reasonable idea.  However it is hubris to think that humans were meant to understand the universe.  Perhaps true understanding is beyond our reach and that we won’t be able to build a detector, or telescope large enough to find out the true nature of the universe.  For the past 200 years we have been picking off the low lying fruit.  Saul Perlmutter got the last of it with the discovery of dark energy by examining type 2 supernovas.  From now on it seems all the projects will get larger and larger and more and more expensive.  I don’t see any particular reason to think that one way is better than another, a telescope, an underground dark matter detector, space telescope or another gravitational detector.  Theorists right now are spinning new theories but the entire edifice of string theory is so big, it contains not only the current standard model but every possible standard model for every possible universe.  My personal feeling is to keep striving and to continue with all the projects, that means yes building the next LHC, with 10 times the power.   It will be expensive but every path forward is expensive now.  Build another LHC, build another space telescope another super K, and what will have to happen is more of the same.  Today an experimental physicist will never do an experiment on his own.  Because of the cost of modern physics he will only share the first page with hundreds of others.  We will have to continue down the same path, more expensive physics projects but less and less actual experiments as the cost continues to rise for each experiment.

 

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