Passage Discussion

[Yu440]

I found this passage tricky!

1st Paragraph: What physicists originally thought: the universe was tiny, hot and dense. After the Big Bang, it expands and cools.

2st Paragraph: BUT Carroll and Chen thinks the Big Bang was not a unique event. There's actually a multiverse!

3rd Paragraph: (I found this paragraph confusing! I understand the concept, I think.) The second law of thermodynamics illustrates why time flows in one direction: it's more likely for a system to go from orderly to disorderly (ie with increasing entropy). (But I don't see how this fits with the rest of the passage? I guess that's why I missed Q23 as well)

4th Paragraph: Carroll and Chen argues that the most common initial condition is actually likely to resemble cold, empty space (which will likely not generate any universe?)
(but the initial condition for our UNIVERSE was still a small, hot, and dense (low entropy) configuration?)

5th Paragraph: our universe occurred from flactuations in an otherwise cold and empty (high entropy) multiverse

6th Paragraph: Because the multiverse is so immense, anything is possible! And it might even happen more than once!


I think I didn't do well on the passage because I didn't fully grasp the concept of entropy. I just intuitively thought "oh entropy=disorder, okay then hot and dense must mean more disorder, and cold and empty must mean less disorder." But it's actually the other way around right?

Patrick, please help!!

[ohthatpatrick]

I can see why the entropy aspects of this passage would be super challenging to anyone not previously acquainted with those ideas. I am fortunate to have long ago abandoned religion and thus have been trying for years to understand all this cosmological science for which I'm am intellectually ill-equipped.

In its simplest terms, the passage is a classic Old vs. New science passage (usually those end with our author giving us her feedback on the New ... is it a gamechanger? is it too soon to say? does it provoke new questions? does it have other implications?). Here, we just have a descriptive passage, with the author laying out C & C's theory while giving it context.

So all we need to pull out of the big picture is
- what was the OLD way / OLD idea?
- what is the NEW way / NEW idea?

OLD way:
Universe started out infinitely small/hot/dense (this is known in common parlance as The Singularity).
The Big Bang refers to the period of extreme inflation. From this time onward, our universe has gotten bigger and cooler, forever increasing in entropy. So it started from lowest possible entropy and flows toward more and more entropy.

NEW way:
Our universe didn't come from some Singularity with low entropy. Instead, it started out from some empty space within a high entropy multiverse. Patches of empty space can have energy fluctuations that can generate their own big bangs. If our universe started this way, then presumably many other universes start this way, arising from energy fluctuations in empty patches of space within a broader multiverse.

-------

The 3rd paragraph is probably where much of the confusion sets in. It's part anecdotal, just letting us know the story of how C & C reached their conclusion. But it's partly germane to the mystery they were trying to solve:
if things always flow from lower entropy to greater entropy, then everything from the Big Bang onward makes sense. But ... what wouldn't make sense is where this initial condition of low entropy came from. (lines 30-33 essentially pose the mystery that C & C were trying to solve)

If we were believing that our universe was the only universe (and hey, maybe even set up by some Creator), then perhaps it makes sense that the initial condition was lowest possible entropy.

But if, as we increasingly do know, we believe that our universe is one of many, existing inside a broader multiverse, we'd expect that multiverse to also be spreading out in ever-increasing entropy, so how would it possess inside of it a sort of ultra-low-entropy thing like a Singularity?

They solved the mystery by saying, "Stop looking for ultra-low-entropy singularities. Just think about our universe inflating from an initial condition of cold, empty space. These other physicists G & V have made the case that faint energy fluctuations on the subatomic scale can actually generate a big bang. So let's just assume our universe came from one of those fluctuations, since patches of empty space would be very common in the vast expanse of a high-entropy multiverse. And the implication of that sort of starting point for OUR big bang is that this would presumably be the starting point for many big bangs for many different universes."

Hope this helps

[YiZ98]

Thanks for the clarification Patrick!

But I am not sure why the tone of the passage is neutural -- the author seems to have a mildly positive attitude towards CC. For instance, he used the word "innovative" in line 37 and "Indeed..." in the last line.

I'm asking this because I'm not sure about question 22, which I chose (A) "an ardent adversary". Is (D) "sympathetic reporter" correct because (A) is too strong and "sympathetic" renders a relative positive attitute to the more neutral term "reporter?"

Thanks!

[NickS909]

Thanks for the clarification Patrick!
....

I'm asking this because I'm not sure about question 22, which I chose (A) "an ardent adversary". Is (D) "sympathetic reporter" correct because (A) is too strong and "sympathetic" renders a relative positive attitute to the more neutral term "reporter?"

....

I know this is almost a year after the fact, but I believe your confusion comes from the word "adversary". Adversary means opponent, which I think its clear the author is not opposing C&C as you pointed out.

In the last paragraph especially we see the author subscribe to this new idea by C&C. I got question 22 wrong as well because I chose Zealous Proponent but I suppose in hindsight that word choice is a bit too strong.