TED Community » Sean Carroll

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• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: It's possible -- but they might be out of reach. That's the fun of research!
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  A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: My pleasure! Thanks to everyone for participating.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: Because we hypothesize that the basic laws of physics are the same all over, and then we test that hypothesis -- and so far it's succeeded! The mass of the electron, the strength of gravity, etc. -- these are all things we can measure far away and long ago, and they seem to have the same values that they do nearby.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: The Guth-Borde-Vilenkin theorem doesn't really say there must be singularities. They made some assumptions, and those assumptions might not apply to the real world. Most crucially, they are only talking about classical spacetimes, not quantum gravity. Everyone believes (or should believe) that singularities aren't "real" in quantum gravity; but we don't know what takes their place.
  
  I'm not very optimistic about loop quantum cosmology or loop quantum gravity more generally, but I'm happy to be proven wrong.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: That depends on what the results will be. It's pretty math, but physics is all about the results.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: I think it changes it, without completely solving the problem. In MWI, the wave function of the universe evolves in a completely deterministic and reversible way. But "where we are" in the wave function seems to necessarily require a random component. Observations are irreducibly random, as far as we can tell.
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  A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: There are a couple of good choices. One is by Andrew Liddle, and the other one is by Barbara Ryden. I'm just typing extra words now because if I don't it won't let me post a comment with links.
  
  http://www.amazon.com/Introduction-Modern-Cosmology-Andrew-Liddle/dp/0470848359/
  
  http://www.amazon.com/Introduction-Cosmology-Barbara-Ryden/dp/0805389121/

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: Not necessarily; it depends on the physical conditions within the substance. Entropy likes to increase, but energy is conserved at the same time. If it costs energy for electrons to hop around, they will tend to stay put.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: I don't know what that one is -- which probably means it's not very popular, if it's a cosmological model.

• A reply on Conversation: LIVE TED Conversation: Join TED Speaker Sean Carroll

  May 19 2011: We're getting new data all the time. For example, we just got evidence of billions of new planets wandering through our galaxy!
  
  http://blogs.discovermagazine.com/badastronomy/2011/05/18/the-galaxy-may-swarm-with-billions-of-wandering-planets/
  
  However, we are still very very far away from nailing down all the terms in the Drake equation. It's the ones involving life and intelligence and civilization that are the most unknown, for obvious reasons. It will probably stay that way for a while.