For me, the highlight of the lecture occurred during the question and answer period, at approximately 1:14:32, when one of the members of the audience asked the following question:
Question: “So, could you explain a bit more on measurement? You said that you have wave and it interacts with an entangled amount of waves and then pops out a particle, right?I found the following response by Dr. Carroll to be the best description of quantum field theory that I have ever come across:
Sean Carroll: “Yes. I did say that, do you want me to say more about that?
“One reason why it’s confusing is because there is sort of two levels of waviness. Alright?
“So, if the world were really made out of particles, but quantum mechanics were true, there would still be a certain waviness about the world because quantum mechanics says that even if there are particles, the way you describe those particles is through a wave function; through a field that fills space and tells you what the probability is of observing that particle. So the world is made of particles, but the observations of the particles are governed by the rules of quantum mechanics, which involves some wave.
“But the quantum field theory philosophy says that there is not even a particle. What you start with is a field - something that looks waving, something that fills all of space, like the electromagnetic field or the gravitational field - then you apply the rules of quantum mechanics to that, and miraculously what comes out when we look at it are particles.
“So quantum mechanics says that what you see when you observe the universe comes to us - in very frequent circumstances - in discrete packets, discrete lumps. Even if the underlying reality is smooth, we see it in individual discrete bits, and it’s the particles that make up you and me that are the discrete bits we see when we look at fields.
“Fields vibrating and interacting with each other is just the most poetic language that I can think of. The math is perfectly straight forward. You’re young enough to study the math. Go for it.”
Additional segments from two other videos:ReplyDelete
Video: Sean Carroll Refutes Supernatural Beliefs
Video: Sean Carroll - The Particle at the End of the Universe: Q&A