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Category: quantum physics – Page 292

There is a lot of speculation about the end of the universe. Humans love a good ending after all. We know that the universe started with the Big Bang and it has been going for almost 14 billion years. But how the curtain call of the cosmos occurs is not certain yet. There are, of course, hypothetical scenarios: the universe might continue to expand and cool down until it reaches absolute zero, or it might collapse back onto itself in the so-called Big Crunch. Among the alternatives to these two leading theories is “vacuum decay”, and it is spectacular – in an end-of-everything kind of way.

While the heat death hypothesis has the end slowly coming and the Big Crunch sees a reversal of the universe’s expansion at some point in the future, the vacuum decay requires that one spot of the universe suddenly transforms into something else. And that would be very bad news.

There is a field that spreads across the universe called the Higgs field. Interaction between this field and particles is what gives the particles mass. A quantum field is said to be in its vacuum state if it can’t lose any energy but we do not know if that’s true for the Higgs field, so it’s possible that the field is in a false vacuum at some point in the future. Picture the energy like a mountain. The lowest possible energy is a valley but as the field rolled down the slopes it might have encountered a small valley on the side of that mountain and got stuck there.

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Neil Gershenfeld is the director of the MIT Center for Bits and Atoms. Please support this podcast by checking out our sponsors:
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Fab Lab community: https://fablabs.io/
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OUTLINE:

Continue reading “Neil Gershenfeld: Self-Replicating Robots and the Future of Fabrication | Lex Fridman Podcast #380” | >

What happened before the Big Bang? In two of our previous films we examined cyclic cosmologies and time travel universe models. Specially, the Gott and Li Model https://www.youtube.com/watch?v=79LciHWV4Qs) and Penrose’s Conformal Cyclic Cosmology https://www.youtube.com/watch?v=FVDJJVoTx7s). Recently Beth Gould and Niayesh Afshordi of the Perimeter Institute for Theoretical Physics have fused these two models together to create a startling new vision of the universe. In this film they explain their new proposal, known as Periodic Time Cosmology.

0:00 Introduction.
0:45 NIayesh’s story.
1:15 Beth’s story.
2:25 relativity.
3:26 Gott & Li model.
6:23 origins of the PTC model.
8:17 PTC periodic time cosmology.
10:55 Penrose cyclic model.
13:01 Sir Roger Penrose.
14:19 CCC and PTC
15:45 conformal rescaling and the CMB
17:28 assumptions.
18:41 why a time loop?
20:11 empirical test.
23:96 predcitions.
26:19 inflation vs PTC
30:22 gravitational waves.
31:40 cycles and the 2nd law.
32:54 paradoxes.
34:08 causality.
35:17 immortality in a cyclic universe.
38:02 eternal return.
39:21 quantum gravity.
39:57 conclusion.

Elizabeth Gould has asked to make this clarification in the written text ” “Despite the availability of infinite time in the periodic time model, this doesn’t lead to thermalization in a typical time-evolution scenario, and therefore doesn’t, strictly speaking, solve the problem related to thermalization in the power spectrum. The reason for this is that, unlike bounce models with a net expansion each cycle, our model has an effective contraction during the conformal phases. Periodic time, therefore, has a unique character in which it reuses the power spectrum from the previous cycles, which is confined to a given form due to the constraints of the system, rather than removing the old power spectrum and needing to produce a new one.”

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A perovskite-based device that combines aspects of electronics and photonics may open doors to new kinds of computer chips or quantum qubits.

MIT

MIT is an acronym for the Massachusetts Institute of Technology. It is a prestigious private research university in Cambridge, Massachusetts that was founded in 1861. It is organized into five Schools: architecture and planning; engineering; humanities, arts, and social sciences; management; and science. MIT’s impact includes many scientific breakthroughs and technological advances. Their stated goal is to make a better world through education, research, and innovation.

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Scientists from Korea’s POSTECH and the US’ Northeastern University have successfully manipulated light using non-Hermitian meta-gratings, turning optical loss into a beneficial tool. They’ve developed a new method for controlling light direction using specially designed meta-grating couplers. This breakthrough could advance quantum sensor research and lead to a range of new applications, such as disease diagnosis and pollution detection.

Light is a very delicate and vulnerable physical phenomenon. Light can be absorbed or reflected at the surface of a material depending on the matter’s properties or change its form and be converted into thermal energy. Upon reaching a metallic material’s surface, light also tends to lose energy to the electrons inside the metal, a broad range of phenomena we call “optical loss.”

Production of ultra-small optical elements that utilize light in various ways is very difficult since the smaller the size of an optical component results in a greater optical loss. However, in recent years, the non-Hermitian theory, which uses optical loss in an entirely different way, has been applied to optics research. New findings in physics are being made adopting non-Hermitian theory that embraces optical loss, exploring ways to make use of the phenomenon, unlike general physics where optical loss is perceived as an imperfect component of an optical system. A ‘blessing in disguise’ is that which initially seems to be a disaster but which ultimately results in good luck. This research story is a blessing in disguise in physics.

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IBM has announced a 10-year, $100 million initiative with the University of Tokyo and the University of Chicago to develop a quantum-centric supercomputer powered by 100,000 qubits.

Quantum-centric supercomputing is an entirely new – and as of now, unrealised – era of high-performance computing. A 100,000-qubit system would serve as a foundation to address some of the world’s most pressing problems that even the most advanced supercomputers of today may never be able to solve.

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