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We have known for about 100 years that our universe is expanding
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The Future of Our Universe by Ashoke Sen
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- 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
