CERN Courier - General relativity versus Newtonian phsyics
No more need for pesky undetectable dark matter!
What I can’t understand is why they used Newtonian physics to confirm Einstein’s theories!
My brother explained thusly:
I actually have no idea about this dark matter stuff, and don’t know much about relativity and quantum physics, but I can mention two things:
1, Newtonian physics isn’t actually wrong in relativistic conditions. It just isn’t as explicit (and therefore isn’t as useful) as the versions with the relativistic terms when you’re talking about stuff that’s going very fast or is very very massive. In particular, Newton did NOT write F=ma, which is what people usually refer to as Newton’s First Law. What he wrote was F=d(mv)/dt, which does NOT assume that mass is constant. He was far too cautious a man for that. So using Newtonian physics to confirm relativity isn’t completely wack.
2, the big String theory debate goes like this:
proponent: "Hey, look, string theory can express all things simultaneously!"
skeptic: "Hmm, very promising! Let’s see how well it works. If I set up this experiment, what does String theory say will happen?"
proponent: "Uh, string theory doesn’t make predictions."
skeptic: "???? So there’s no way for me to test to see if it’s right?"
proponent: "No."
skeptic: "Then what good is it? You’re not talking physics any more, you’re talking philosophy."
purist: "If you can’t apply the scientific method, then it’s not a science. Go away, fanatic, and take your representations with you. I don’t care if they do combine all the forces of nature into one neat form."
proponent: "Well, maybe we’ll figure out a way to do predictions one day."
3. When I think of quantum physics, I think of Dave Hamm, our high school physics teacher: "You can’t just throw a basketball up to any old height. You can only throw it so high." He had other gems like, "Friction is a big, hairy monster that lives on surfaces, gobbles up kinetic energy, and spits it back out as heat." Crazy as it’s phrased, send that to your college physics prof–he’ll have to agree. I also think of those little ketchup packages you get from fast food places. Why are they so small? Everyone needs more than one, and they don’t even make a good quantum.
(Fred’s pretty smart.)
