How lucky are we? That at some point in the past, quantum fluctuation perhaps had caused variations in density/temperature that accumulate into galaxy and stars. That for the longest time ever imagined, there’s a super insignificant blip in spacetime where humanity exists. That we were able to think. Knowing of our fragility, reminds me how insignificant we all are, like we are against bigger concerns than those that our civilization has placed on us, like we should live more in the moment, like we should be more unified.
I first saw this book as a recommendation from my astronomy 101 teacher in university. The next encounter was a book club recommendation I saw in IG. So I decided to pick it up. I totally loved it. Katie Mack really summarized a huge bulk of the cosmological thinking today and where it’s heading. With all it’s challenges introduced, it’s very clear that the book also carries so much love for the subject, lots of mind-blowing ideas/observations, and a very clear explanation of difficult concepts.
I would definitely recommend this book, particularly for those in the field, but also those who wants to be enlightened and freed by the daily life and see the bigger picture. As we look around at a distance in the far sky, we look back in time and the history of the conditions that our galaxy grew up in. Past and present events is travelling to us from a distance and will only be visible in our future. Realizing that “Now” is only specific to you. And in that way, I guess life goes on.
How universe will end and what we don’t know
Earth would die from sun expanding over next few million years, our galaxy would then collide with our neighbor Andromeda in 4 billion years.
Like firing a cannon up the atmosphere, the universe could: 1. slowly stop expanding and collapse (Big Crunch. Would it then restart another big bang?) 2. it could slow down and be stationary 3. it could expand forever
What we know is that the universe expansion is in fact accelerating, leading to the 3rd option (by this completely unknown thing we hypothesized as dark energy). In this case there will be a point in spacetime where light can’t catch up with the recession speed. Eventually our visibility fades, everything becomes isolated, there will be no interactions, black holes evaporate, more disorder, entropy (entropy can only increase. Every time you try to put order, you create disorder elsewhere), heat, death.. And when entropy reaches its global max, perhaps even time is gone.
But would there be a way to shift the system back into a low-entropy state (new big bang)? Possible. 🤯
Can dark energy expand to the point that planets and galaxies dissipate, tearing atoms apart (big rip)? Possible
We are also up against the unknown fate of Vacuum decay. The discovery of Higgs field (theory determining particle mass and charge. Higgs boson is the particle) tells us about Higgs vacuum. It brought in the idea that our cosmos is only metastable. If a BOOM large enough to kick the higgs field over to a more stable state, or if quantum tunneling of the higgs field by some unfortunate chance sets it off.. The vacuum delay could happen. We’ll die, the nature of particles we know are rearranged, cancelling the universe entirely. It could happen anytime.
Expanding our perspective along with the universe
We don’t know much and it’s terrifying yet hopeful. That there’s no shortage of impressive, motivated attempts, even when it’s hard to find supporting data and no guarantee that there is anything. Building experiments at the extremes involves lots of beurocracy, expenses, efforts, international politics, time, with the unguaranteed promise of finding new particles.
It would be easier to build new instrumentation to observe the cosmos than building controlled experiments like the particle colliders. Yet there’s a lack of signs. With still lots of holes in our understanding (dark energy, dark matter, quantum gravity..), the fact that all data fits perfectly with our model is a worst case because we don’t know what the current model is missing. To look for a new model that can replace the old is no easy feat.
Novel ideas that may not work can still spur new ways of looking at the problem. We need new perspectives for old problems. That way you’ll have more insight of whatever data the universe has to offer.
Favorite quotes
Someday, … the Earth will die, and the cosmos itself will come to an end. In the meantime, we have the entire universe to explore, pushing our creativity to its limits to find new ways of knowing our cosmic home. We can learn and create extraordinary things, and we can share them with each other. And as long as we are thinking creatures, we will never stop asking: “What comes next?”
“I love the fact that my work, even if I do it 100 percent perfectly and I’m an incredible scientist, it changes nothing about the fate of the universe,” she says. “All we are trying to do is understand it. And even if you do understand it, we can do nothing to change it. I think that’s freeing rather than scary.”