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If Isaac Newton suddenly popped out of a time machine, he’d be delighted to see how far physics had come. Things that were deeply mysterious a few centuries ago are now taught in freshman physics classes (the composition of stars is one good example).
Newton would be stunned to see enormous experiments like the Large Hadron Collider (LHC) in Switzerland — and possibly perturbed to learn that his theory of gravity had been superseded by one dreamed up by some fellow named Einstein. Quantum mechanics would probably strike him as bizarre, though today’s scientists feel the same way.
But once he was up to speed, Newton would no doubt applaud what modern physics has achieved — from the discovery of the nature of light in the 19th Century to determining the structure of the atom in the 20th Century to last year’s discovery of gravitational waves. And yet physicists today are the first to admit they don’t have all the answers. “There are basic facts about the universe that we’re ignorant of,” says Dr. Daniel Whiteson, a University of California physicist and the co-author of the new book “We Have No Idea: A Guide to the Unknown Universe.”
What follows is a brief tour through seven of the biggest unsolved problems in physics. (If you’re wondering why head-scratchers like dark matter and dark energy aren’t on the list, it’s because they were in our earlier story on the Five Biggest Questions about the Universe.)
1. What is matter made of?
We know matter is made up atoms, and atoms are made up of protons, neutrons, and electrons. And we know that protons and neutrons are made up of smaller particles known as quarks. Would probing deeper uncover particles even more fundamental? We don’t know for sure.
We do have something called the Standard Model of particle physics, which is very good at explaining the interactions between subatomic particles. The Standard Model has also been used to…