Completed
This possibility has been known for about 50 years.
Class Central Classrooms beta
YouTube videos curated by Class Central.
Classroom Contents
The Future of Our Universe by Ashoke Sen
Automatically move to the next video in the Classroom when playback concludes
- 1 Date: 27 december 2021, 17:30 to
- 2 The Future of Our Universe
- 3 Conclusion
- 4 We have known for about 100 years that our universe is expanding
- 5 The universe was thought to contain three kinds of sources of energy mass density:
- 6 In 1998 two independent experiments made a profound discovery.
- 7 Best explanation available today:
- 8 Dark energy' has now become a household word.
- 9 The classical story
- 10 Presence of dark energy causes the universe to undergo an accelerated expansion
- 11 Due to the accelerated expansion it is physically impossible for us to reach very faraway places in the universe.
- 12 The idea of multiverse is a reality even if it sounds like a science fiction.
- 13 In special theory of relativity we learn that
- 14 Conformal space-time diagram:
- 15 Even though the expansion of the universe pulls comoving objects apart,
- 16 In the far future,
- 17 The Quantum Story
- 18 The story begins with that of a particle sliding on a hill.
- 19 Our interest will not be in a particle, but in the whole universe.
- 20 A familiar example: Magnetic field Bx, By, Bz
- 21 Unlike magnetic field it has only one component which we shall
- 22 The properties of these two phases are typically very different.
- 23 Let us recall the case of a particle on a hill.
- 24 Can a similar tunnelling happen in a quantum field theory?
- 25 The surface begins an accelerated expansion, converting the potential difference to kinetic energy.
- 26 What will be the fate of any living or non-living object in A during this process?
- 27 This possibility has been known for about 50 years.
- 28 When we write the theory of the Higgs field, we write a nice form
- 29 But the situation is much more complicated.
- 30 1. Supersymmetry has been very useful in addressing many issues in particle physics.
- 31 Are we living in a false vacuum?
- 32 'String theory' is an attempt to have such a fundamental theory
- 33 If string theory is right then one of these minima describes the phase of the theory we are living in.
- 34 How do we know if we are living in a false vacuum?
- 35 Assuming that we are living in a false vacuum,
- 36 2. Calculate the volume of space-time between the past light-cone at and at t + it
- 37 Probability of being hit: ht it
- 38 Since theory cannot tell us the actual risk, can we invoke experiment?
- 39 Suppose one day a small asteroid hits the earth and destroys everything within 100 meter radius of impact.
- 40 I hope you would agree that the possibility, however small, that
- 41 As in most adventures, we need to leave home.
- 42 Let us recall some of the facts we learned.
- 43 If the rate of universe production exceeds the rate of destruction,
- 44 If we remain confined within our galaxy then our annihilation probability will be controlled by the rate of destruction.
- 45 We can overcome this fate if we spread out into the currently accessible universe.
- 46 Note that dark energy is the hero of the story.
- 47 Conclusion
- 48 Dark energy helps those who help themselves.
- 49 Q&A
