“Time really exists”: Highlights from our live-chat with Sean Carroll

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Sean Carroll took a two hour break from his vacation to chat on TED Conversations about his talk on the nature of time and other questions about time, the cosmos, and poker. Thanks to everyone who came by with questions, and to Sean for exciting answers about an enormous topic. As proof that we was in Vegas, and that he’s good at poker, he sent a photo of the token he received for winning a tournament:

Here are some other highlights:


Sean Carroll: Our brains did not evolve to study physics or cosmology; yet, we’re doing a very good job.


Sean Carroll: Interestingly, it’s very possible for two universes to bump into each other without creating much fuss. That’s because chances are that one universe is much, much bigger than the other one; the colliding universe would just show up as a hot spot in the bigger universe, which would eventually come to equilibrium with all the stuff around it. Cosmologists are actively looking for signs of such universes in the cosmic microwave background.


Nafissa Yakubova: How does this knowledge about Universe and Time affect your everyday life? ( beyond your work)

As a space and time enthusiast, my layman knowledge about universe has a huge impact on how my mind works and how I live my daily life. I’m curious about how it’s for YOU as a pro physicist and cosmologist: could you please share how it affects your thinking, views and daily life?

Sean Carroll: I think it affects my everyday life quite a bit. When you fly to a physics conference, and you’re in the airport waiting to board, it’s usually not hard to pick out the other physicists. But I try to blend in to some extent.

Physics helps you think quantitatively about the world, understand hypothesis-testing, and get some feeling for the uncertain values of real-world measurements. All very useful skills!


Andrew Cross: Sean, you stated that: “…empty space essentially lasts forever (but) since empty space gives off radiation there’s actually thermal fluctuations and it cycles around all the different possible combinations of the degrees of freedom that exists in empty space.”

Does this make life possible in the empty space era?

Sean Carroll: Yes, absolutely, at least in principle. Indeed, that’s the big question: if a model like this is right, why aren’t we random fluctuations in an otherwise empty space, rather than finding ourselves in a warm and inviting universe filled with stars and galaxies?


Piotr Bulczak: Does that all mean that there is actually nothing like time? Is it just a our “feeling” of the changes around, states changes, fluctuations? Without any change around us would we be in present time time? Ok, just said there is no time in fact. :-)

Sean Carroll: I’m someone who believe that time really exists. Otherwise how would we know when to participate in the TED chat?