a universe from nothing

Rating

7/10 It’s by no means an easy read. But it was by no means an easy feat either to try to write a book that makes so much of extremely advanced physics and mathematics so accessible to the general public. Hats of to Lawrence for this.

For anyone generally curious about the universe, but generally undereducated in cosmology, physics and mathematics, this is a nice read that dumbs things down, but not so much that you are constantly left with the feeling that a lot has been left out. I was a bit confused about how the initial 2-3 chapters were tying into the actual question of how something came out of nothing, but by chapter 5 or so the story became clearer and the answer started to unfold. From that point on, it was a great read, although I wish I went a bit slower, with lot more notes and a lot more attempts at fully grasping the arguments being laid out. It’s the kind of book where one is better reading 2-3 pages at the time and then digesting the content for the rest of the day. That said, I am leaving with a better idea of how something can come out of nothing, based on our current theories. As well as why a divine creator isn’t necessary for any of it.

Synopsis

If before Darwin people pointed at the complexity of nature as evidence for divine creation. But after Darwin had no good arguments against evolution by natural selection. Than in this book Krauss does the same for the last standing argument in favor of god. Namely that there has to be a divine creator that started it all. Although the book doesn’t claim we have the full answer for how a universe can spring out of nothing yet. It gives enough evidence that we are on the right path to fully discovering it soon - and luckily we live during the time of the universe where it seems we might be able to probe this question ever further (unless the reality we see is far stranger than we can imagine).

Notes

“Before going further, I want to devote a few words to the notion of ‘nothing’… For I have learned that, when discussing this question in public forums, nothing upsets the philosophers and theologians who disagree with me more than the notion that I, as a scientist, do not truly understand ‘nothing.’ (I am tempted to retort here that theologians are experts at nothing.)”

• savage! italics added by me

Chapter 1

• first person to propose Big Bang was Lemaitre in 1927 (less than 100 years ago!)
• given a star of certain fixed brightness, how does its perceived brightness scale with distance from the observer?
  • a star emits its light in a spherical shape
  • thus its total brightness is equally distributed over the area of a sphere
  • a sphere’s area is $4\pi r^2$
  • thus the area increases as the square of the distance from the star to the observer
  • hence the brightness scales as the inverse of the square of the distance from the observer to the star
• we can tell what elements sun is made of just by refracting light into its constituent wavelengths and seeing which wavelengths are missing
  • these missing wavelengths are like a unique signature for specific atomic structure of elements that absorb this light in and around the sun
• since we discovered that nearly all the observable galaxies are moving away from us, and we are not a center of the universe, it must mean that the universe is expanding
  • and since it’s expanding everywhere, rewinding time back far enough, at some point all of the matter must have been somewhere at a single point in time
  • that’s the simple deductive reasoning for the Big Bang
• another evidence for Big Bang is the theoretical prediction of what elements we should see in the universe and at what abundances
  • if the Big Bang happened, it must have been extremely hot at the beginning but then cool down very rapidly as the universe expanded at an extreme rate. During the rapid cooling only certain elements could have formed and by that token we should see those elements in great abundances
  • this is exactly the case (the elements in question are hydrogen, deuterium, helium and lithium) and our predictions bang on fit with our observations
• since Big Bang only produced lighter elements like hydrogen, deuterium, helium, and lithium, all the heavier elements we depend on, like oxygen, carbon, iron and so on, must have come from somewhere else
  • this somewhere else turns out to be the cores of exploding stars that sustain blazing hot temperatures for longer and allow nuclear fusion to form heavier elements
  • thus we are literally made of star stuff
• if you make a small circle between your thumb and your forefinger and point it at a bare patch of clear night sky, then in that circle, with humanities largest telescopes in operation today, we can discern about 100,000 galaxies, each containing billions of stars - that’s how ginormous the universe is - utterly incomprehensible scale!

Chapter 2

• how did we discover/postulate dark matter?
  • Vera Rubin first observed that our galaxy rotates way faster than what can be accounted for by gravitational forces between all the visible matter inside of it
  • thus she postulated that there must be some other “dark matter” that adds more mass into our galaxy and hence provides higher gravitational forces to account for the speed of the rotation
  • this dark matter could be just regular planets and asteroids that don’t shine and thus aren’t visible
  • but we can run calculations based on the amounts of hydrogen, helium and lithium that we see in the universe, relate these amounts to how much matter must have been present in the big bang to produce this much observable light elements, and then know that if these two quantities don’t account for each other, the remainder of the big bang matter must be inside of dark things like planets and asteroids
  • this calculation results in an expected ratio of 2 to 1; dark to visible matter
  • but to explain the observations of Vera Rubin, there would have to be 10 to 1, dark to visible matter
  • so there must be some truly invisible, dark matter, that we cannot detect, but that interacts with the gravitational field
• how will the universe end?
  • that depends on the geometry of the universe
  • if the universe is closed, meaning if you could look far enough you would see the back of your head, then it will at some point collapse on itself (results of running General Relativity calculations)
  • if the universe is open, then it will expand forever (heat death)
  • but if it’s flat, the expansion will keep approaching zero, but never fully reaching it

Chapter 3

• it’s also possible to measure the curvature of the universe by measuring the angles inside of a giant universe spanning triangle
• if they are more or less than 180 degrees, we know we live in an open or a closed universe; if there are exactly 180 degrees in it, we live in a flat one
• so how can we make a huge intergalactic triangle and measure its angles?
  • well, we can use the cosmic microwave background (CMB) to our advantage
  • the CMB is the first (or the last?) “visible wall” we can see when we look deep into the universe
  • by mapping the CMB, we are essentially mapping how the universe looked when the first neutral elements started to form and the universe was no longer just a soup of protons and electrons forming an impenetrable plasma
  • at this point the radiation started scatter instead of just being absorbed and so the scattered radiation has been traveling ever since then to us and to every other place in the universe
  • this first scattering surface formed when the universe was about 300,000 years old and if we look at it from earth, 1 degree distance spans about 300,000 light years
  • whatever pattern we see in this span must be imprinted on it causally by nothing else than time
  • no complex physical processes and interactions between matter had yet time to take place
  • and because we are looking at a patch that’s 300,000 light years wide at the time when the universe is 300,000 years old, we can witness the first clumps of matter collapsing into itself as they realize that gravity is pulling them together (gravity propagates at the speed of light)
  • so, we can look at the pattern of these clumps and compare it to simulations of how these clumps should look if the light from them traveled to us along a straight line, inward bend line or outward bend line
  • this is what we exactly did, and it turned out that the straight line path fits the best!
  • so according to a giant intergalactic triangle that literally spans time itself (some 13 billion years of time), we live in a flat universe that will never stop expanding, but the expansion will keep slowing forever

Chapter 4, 5, 6 etc.

• I read this book while moving countries (from Slovakia to Belgium) and simply wasn’t as diligent as usual with taking notes after each chapter
  • it’s pretty clear my retention of information suffered due to this because I couldn’t fully follow the summaries of his arguments in the final chapter
  • nonetheless, here are some more mind-blowing facts I would like to remember from this book
• we live in a special time where we can observe a massive amount of galaxies and even more massive amount of stars within them. Because, based on our observations and theories about the expansion of the universe, in the far far future, all galaxies will get so far from each other and the space will be expanding so fast, that no light will be able to travel from one galaxy to the next. So a future cosmologist will have no real way of knowing that their own galaxy isn’t in fact the entire universe. They will have no way of probing or even generating hypothesis about big bang or inflation. The knowledge, and if we are correct in our theories, the truth of the origin of our universe will be forever lost.
  • we think that as time will pass, the knowledge will expand and science will progress, but this prediction shows how it is possible for nature to progress to such a state that it literally makes it impossible for an inside observer to comprehend and probe its origin and evolution. But this also makes me think that this is an extreme example and science/knowledge/truth can digress even on more minute grounds - just look at how we, as western society, have forgotten the ancestral knowledge of native plants and native ecosystems
• empty space has energy… and that’s crazy! It took us a while to realize this but it’s the reason why the universe’s expansion is speeding up; it is fueled by the energy of empty space. As far as I understood the contents of this book, we are still not sure why this is so and we simply treat it as a cosmological constant (as Einstein first postulated and then later retracted). But possible explanations can be found in quantum theory - which I still do not understand well, even after reading this book, so I will not attempt to retell here what Krauss tried to explain in the book - clearly, I will need to read this book again if I decide I want to understand it better :)
• there are at least 2 types of possible multiverses that we can currently support with our theories (or at least 2 I remember from the book). The first one is a classical 4 dimensional universe that spawns completely self-contained universes during the inflation period. The inflation period is pretty much a point in time when the space itself has been expanding faster than the speed of light. In this expansions, pockets of space would exit the inflation earlier than the surrounding space, essentially trapping itself infinitely far away from the rest of the still inflating universe. This, according to our theories, must have happened everywhere, all the time, creating one 4 dimensional universe with millions of self-contained 4 dimensional universes within it.
• the second type of a multiverse is the one we postulate through string theory. In this multiverse there are more than 4 dimensions and our universe is just one of gazzilions of possible universes that we can account for when we run the math of a 4 dimensional universe being embedded in a higher dimensional spacetime of string theory. So if string theory is correct, we are jut 3 dimensional creatures, living in spacetime that itself is embedded in a higher dimensional reality.
  • I like the first multiverse better, but nature doesn’t care about what I like :)