The speaker explores two big unanswered questions in the universe: how many universes exist, and why we can't see evidence of alien life. They start by discussing how our understanding of the universe has changed significantly, with theories suggesting the existence of multiple universes, possibly in up to 11 dimensions. Some scientists estimate that there could be 10 to the 500 universes, while others believe in an infinite number of universes.
The speaker then shifts to the question of alien life, noting that with half a trillion planets in our galaxy, it's likely that some support life. However, despite numerous planets being discovered, we see no convincing evidence of alien life. Several possible explanations are offered, including the possibility that advanced civilizations self-destruct, or that they're simply not transmitting signals in a way we can detect.
The speaker concludes by highlighting the importance of continued exploration and the potential for new discoveries, including the possibility of creating life from scratch or finding evidence of alien life through spectroscopic analysis of nearby planets. Ultimately, the quest for knowledge and understanding is what drives us forward, and the unanswered questions are what make the world seem amazing.
Here are the key facts extracted from the text:
1. The Sun is so big that it would literally fit one million Earths inside it.
2. There are about 400 billion stars in the Milky Way galaxy.
3. There are maybe 100 billion galaxies detectable by our telescopes.
4. Space itself is expanding at an accelerating pace.
5. The vast majority of galaxies are separating from us so fast that light from them may never reach us.
6. Our physical reality on Earth is intimately connected to those distant, invisible galaxies.
7. Recent theories in physics, including string theory, suggest that there could be countless other universes.
8. These universes could be built on different types of particles, with different properties, obeying different laws.
9. Most of these universes could never support life.
10. The leading version of string theory predicts a multiverse made up of 10 to the 500 universes.
11. This number is so vast that if every atom in our observable universe had its own universe, and all of the atoms in all those universes each had their own universe, and you repeated that for two more cycles, you'd still be at a tiny fraction of the total.
12. Some physicists think the space-time continuum is literally infinite and contains an infinite number of so-called pocket universes.
13. Quantum theory suggests that huge numbers of parallel universes are being spawned every moment.
14. In the past year, the Kepler space observatory has found hundreds of planets just around nearby stars.
15. If you extrapolate that data, it looks like there could be half a trillion planets just in our own galaxy.
16. If any one in 10,000 has conditions that might support a form of life, that's still 50 million possible life-harboring planets right here in the Milky Way.
17. Our Earth didn't form until about nine billion years after the Big Bang.
18. Countless other planets in our galaxy should have formed earlier, and given life a chance to get underway billions, or certainly many millions, of years earlier than happened on Earth.
19. SETI, the Search for Extraterrestrial Intelligence, is now releasing its data to the public so that millions of citizen scientists can bring the power of the crowd to join the search.
20. Within the next 15 years, we could start seeing real spectroscopic information from promising nearby planets that will reveal just how life-friendly they might be.