There doesn’t have to be anything that “made” the Big Bang happen. The universe could just very well last forever.

Of course it doesn’t matter what our preferences are — we’ll have to see what Nature actually chooses to do.

I have hardly any science background and can only barely grasp most of what you write about but I have been fascinated by the following questions my entire life and I bet a day doesn’t go by where I don’t (very unscientifically!!) contemplate the following:

What truly is infinity? Does infinity bother you?
Isn’t it true that if we can describe something (ie the expanding universe), then what is beyond that “expanding thing”?
Is it true that it is not possible to understand what comes afterwards?
Or….what actually precipitated the Big Bang? Isn’t it true that no matter what the theory is of what happened or what was at pre-Big Bang, there still has to then be a precipitating event that made the pre-pre Big Bang even happen?

Do these questions “bother” cosmos scientists?

Thanks!
Cindy

I don’t think it’s helpful that the Hawking radiation doesn’t interact much — at least, I don’t see what it would help with.

Glad you liked the book!

Is it at all helpful that a lot of the hawking radiation coming off of an evaporating black hole in an emptyish universe will cross a cosmological horizon before it interacts with anything?

Compliments on the book. I very much enjoyed reading it. It reads kind of like a cross between pop-science and a philosophy book but still provides enough technical info to teach something new to those of us who have had years of rigorous training.

That’s funny – I do that all the time too. I cannot spend too much time in one place reading about things that take you many places. It.. itches.

Recently though, I have found coffee shops and the like to be rather limiting of ones imagination, even more so than a room with four white walls, because they impose a particular atmosphere on the thinker. The park is now my favorite hangout. It is a little overwhelming at first (for a large enough park), but I heartily recommend it.

As for losing weight without physical exercise, I am living proof that a man can lose 30 pounds in a couple of weeks via unhealthy manner of thought.

-A

… seriously, mucho thanks for taking the time to demonstrate the wonder of real science to a wider public…. if more people can understand science… maybe there’s hope for poetry!

I enjoyed reading your book. I especially liked your way to explain complex facts and that you clearly distinguish between established and speculative ideas. Sadly, in the epilogue you help to spread a common misunderstanding about Christians. We Christians do not oppose Darwin’s theory because we think that we matter, but because we think that God and what he tells us in the bible matters. This is just the opposite of what you write. Likewise, in the medieval worldview it’s not an honour to live near the centre of the universe. Belonging to the lower spheres means being imperfect and mortal, while the perfect and eternal beings live in the outer spheres. This also shows that God matters, not human beings.

Personally I fail to see how your “multiverse did it” explanation of the arrow of time is any better then the “god did it” approach (even though I’m an atheist). Both multiverse and god are similarly ill-defined concepts completely inaccessible to empirical science.

Glad you liked the book!

I have a question that belongs to the previous chapter – you said cosmologists would say that inflation would robustly follow from a high energy dense region of space, creating a fresh low entropy universe – the only problem was, the high energy space was in itself very low entropy, with high entropy being actually empty space.
My question is – what about a big crunch? If the universe were right now to be overtaken by gravity, so that everything starting collapsing into each other, but still in an entropy increasing, full of black holes, messy way, then would inflation robustly follow the result of that? Because that configuration is of course very high entropy. What am I missing?

I’ll also add that I loved the book, absolutely wonderful fun, keeping me excited as I now plow through my first undergraduate year in physics, calculating uniform spherical charges and such.

I think that de Sitter space is where we are going, so a challenge for cosmology is how we can escape that fate. The problem with high-energy de Sitter space is that it’s a low entropy configuration, so you have to explain why you’re ever in such a state in the first place.

Glad you liked the book!

You show this schematically in Figure 87. A couple of questions about the figure:

1. The vertical axis is labeled “time”. Does the horizontal extent represent physical space? Or maybe entropy (in 2-D?)

2. The spawned universes are shown as coevally coming from the parent. I assume this is just for representational convenience.

Do you believe that de Sitter space is a necessary condition for birthing a baby universe, or merely more likely given the longevity of such a state? Might it be possible that conditions for instantiating the high energy inflaton could be more favorable in a younger universe, maybe even in the context of a black hole? (I’m itching to coin the term “de Baby Sitter space.”}

And finally, thank you for this delicious book. It’s just the sort of intellectual repast that I enjoy, even though I am far from sated.