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#124 - Matt Taylor - Multiverse



“Despite its name, the big bang theory is not really a theory of a bang at all. It is really only a theory of the aftermath of a bang.”

Alan H. Guth


  • 1932 –Born OTD the late the great Alan Bean (d. 2018)

This week's guest


Matthew Graham George Thaddeus Taylor (born 1973)

The British astrophysicist employed by the European Space Agency.

He is best known to the public for his involvement in the landing on Comet 67P/Churyumov–Gerasimenko by the Rosetta mission Philae lander, which was the first spacecraft to land on a comet nucleus. He is Project Scientist of the Rosetta mission.

Space News

A Spatially Resolved au-scale Inner Disk around DM Tau

Tomoyuki Kudo at al

Watching the making of a Solar System similar to our own.

ESA greenlight Sabre

ESA, together with the UK Space Agency (UKSA) recently reviewed the preliminary design of the demonstrator engine core of the Synergetic Air-Breathing Rocket Engine (SABRE), which Reaction Engines will use to undertake ground-based testing at test facility at Westcott, Buckinghamshire, which is currently under construction.

“The positive conclusion of our preliminary design review marks a major milestone in SABRE development,” comments Mark Ford, heading ESA’s Propulsion Engineering section. “It confirms the test version of this revolutionary new class of engine is ready for implementation.”

2nd time lucky

Three crew members have arrived safely at the International Space Station, following a successful launch and docking of their Soyuz MS-12 spacecraft Thursday.

The Soyuz spacecraft carrying Nick Hague and Christina Koch of NASA and Alexey Ovchinin of the Russian space agency Roscosmos launched at 3:14 p.m. EDT (12:14 a.m. Friday Baikonur time) from the Baikonur Cosmodrome in Kazakhstan. Hague, Koch and Ovchinin docked to the space station’s Rassvet module at 9:01 p.m. after a four-orbit, six-hour journey, and are scheduled to open the hatch and be welcomed aboard the orbiting laboratory at approximately 11:10 p.m. Their mission, Expedition 59, officially began at the time of docking.

The arrival of Hague, Koch and Ovchinin restores the station's crew complement to six. They have joined Anne McClain of NASA, David Saint-Jacques of the Canadian Space Agency and Expedition 59 Commander Oleg Kononenko of Roscosmos.

Crazy SLS News from Jim Bridenstine

  • During a hearing of the Senate Commerce committee the chairman Sen. Roger Wicker opened by asking Bridenstine about EM1's ongoing delays.

  • "SLS is struggling to meet its schedule, We are now understanding better how difficult this project is, and it’s going to take some additional time. I want to be really clear. I think we as an agency need to stick to our commitment. If we tell you, and others, that we’re going to launch in June of 2020 around the Moon, I think we should launch around the Moon in June of 2020. And I think it can be done. We should consider, as an agency, all options to accomplish that objective."

  • One heavy-lift rocket to launch a fully fueled upper stage like a Centaur upper stage,.

  • Second heavy-lift rocket would launch an Orion capsule and its service module into orbit, and

  • These two vehicles would dock.

  • The fueled upper stage would then inject Orion into a lunar orbit.

  • "I want to be clear, we do not have right now the ability to dock the Orion crew capsule with anything in orbit, So between now and June 2020 we would have to make that a reality."

  • In 1966; John Young and Michael Collins Gemini 10 mission saw an Agena upper stage launched into space,100 minutes later a Gemini capsule. The spacecraft and Agena docked at about 270km above the Earth, and then burned the Agena's engine to go as high as 760km,

  • Bridenstine did not name rockets during the hearing, but it seems almost certain that at least one of them would be a Delta IV Heavy,

  • Orion has already flown on a Delta IV H spacecraft to an altitude of 3,600km in 2014.

  • Both United Launch Alliance and SpaceX—with its Falcon Heavy rocket—would be invited to bid on the second launch.

  • Can you build a Delta Iv heavys in time? Very hard to see that happening as they normally

  • "It is important to remember that United Launch Alliance is co-owned by Boeing and Lockheed Martin. Boeing is the primary contractor for the SLS rocket. The statement reflects this nuance." Eric Berger

  • “That was a really polite way of stating the extremely difficult position ULA was put into by Bridenstine's trial balloon. It's like having your extremely jealous divorced dad's young girlfriend come onto you at a family gathering where you were going to ask him for more money for college” Greybeardengineer

  • Docking - Orion can dock with the gateway, so how hard is this? Probably more about procedures than hardware.

  • Alabama's senator Richard Shelby

  • He is a SLS or the Senate Launch Systems biggest fan.

  • Already opposed to this plan.

  • "I just don't understand what his beef is," Elon Musk

Space Word of the week

Eternal Inflation

The theory of inflation states that he inflationary epoch lasted from 10−36 (one undecillionth) seconds after the conjectured Big Bang singularity to sometime between 10−33 (one decillionth) and 10−32 (100 nonillitonth) seconds after the singularity. Following the inflationary period, the universe continues to expand, but at a less rapid rate.

According to eternal inflation, the inflationary phase of the universe's expansion lasts forever throughout most of the universe. Because the regions expand exponentially rapidly, most of the volume of the universe at any given time is inflating. Eternal inflation, therefore, produces a hypothetically infinite multiverse, in which only an insignificant fractal volume ends inflation. Ie our universe is just a little bubble where the vacuum energy became stable enough for normal inflation (dark energy) to take over.

Can’t talk about this without talking about Alan Harvey Guth the Victor Weisskopf Professor of Physics in the Massachusetts Institute of Technology. Along with Alexei Starobinsky and Andrei Linde, he won the 2014 Kavli Prize “for pioneering the theory of cosmic inflation

Inflation theory has gone on to be supported by satellites like WMAP and Planck and the CMB we discussed last week. Why do this maps show such uniformity, Since inflation started with a far smaller amount of matter than the Big Bang had presupposed, an amount so small that all parts would have been in touch with each other. The universe then inflated at billion times the speed of light so the homogeneity remained unbroken. The universe after inflation would have been very uniform even though the parts were not still in touch with each other.

In December 1981, Guth read a paper from Moscow physicist Andrei Linde saying that the whole universe is within just one bubble

Guth's original formulation was problematic, as there was no consistent way to bring an end to the inflationary epoch and end up with the hot, isotropic, homogeneous universe observed today. Although the false vacuum could decay into empty "bubbles" of "true vacuum" that expanded at the speed of light, the empty bubbles could not coalesce to reheat the universe, because they could not keep up with the remaining inflating universe.

Paul Steinhardt, one of the original architects of the inflationary model, introduced the first example of eternal inflation in 1983,[1] and Alexander Vilenkin showed that it is generic.[2]

In 1982, this "graceful exit problem" was solved independently by Andrei Linde and by Andreas Albrecht and Paul J. Steinhardt[5] who showed how to end inflation without making empty bubbles and, instead, end up with a hot expanding universe. The basic idea was to have a continuous "slow-roll" or slow evolution from false vacuum to true without making any bubbles. The improved model was called "new inflation."

In 1983, Paul Steinhardt was the first to show that this "new inflation" does not have to end everywhere.[1] Instead, it might only end in a finite patch or a hot bubble full of matter and radiation, and that inflation continues in most of the universe while producing hot bubble after hot bubble along the way. Alexander Vilenkin showed that when quantum effects are properly included, this is actually generic to all new inflation models.[2]

Using ideas introduced by Steinhardt and Vilenkin, Andrei Linde published an alternative model of inflation in 1986 which used these ideas to provide a detailed description of what has become known as the Chaotic Inflation theory or eternal inflation

Alan Guth's 2007 paper, "Eternal inflation and its implications",[3] states that under reasonable assumptions "Although inflation is generically eternal into the future, it is not eternal into the past." Guth detailed what was known about the subject at the time, and demonstrated that eternal inflation was still considered the likely outcome of inflation, more than 20 years after eternal inflation was first introduced by Steinhardt.

Where is the proof

The CMB may have some proof there is a massive cold patch in the bottom right hand part of the Mollweider map of the CMB that may have been caused by a`collision with another bubble universe. But Occams razor says we must first take two more probable reasons. First there is about a 1in50 chance that it’s just random, so one in every 50 universes would have apatch like this just out of randomness, second that there is a massive void in space, but some recent papers have made this less likeley, by looking at other voids to check the difference in temperature.

Jamie spotted a paper

Testing Inflation with Large Scale Structure: Connecting Hopes with Reality

Marcelo Alvarez, et al

(Submitted on 15 Dec 2014)

The statistics of primordial curvature fluctuations are our window into the period of inflation, where these fluctuations were generated. To date, the cosmic microwave background has been the dominant source of information about these perturbations. Large scale structure is however from where drastic improvements should originate. distribution.

Perimeter Associate Faculty member Matthew Johnson ““We’re trying to find out what the testable predictions of this picture would be, and then going out and looking for them.” Specifically, he has been considering the rare cases in which our (potential) bubble universe might collide with another bubble universe. He lays out what this might look like: “We simulate the whole universe. We start with a multiverse that has two bubbles in it, we collide the bubbles on a computer to figure out what happens, and then we stick a virtual observer in various places and ask what that observer would see from there.”

In analyzing the Planck Satellite data from 2013, Anna Ijjas and Paul Steinhardt showed that the simplest textbook inflationary models were eliminated and that the remaining models require exponentially more tuned starting conditions, more parameters to be adjusted, and less inflation. Later Planck observations reported in 2015 confirmed these conclusions.

A 2014 paper by Kohli and Haslam called into question Their paper concluded that the theory of eternal inflation based on random quantum fluctuations would not be a viable theory, and the resulting existence of a multiverse is "still very much an open question that will require much deeper investigation".

Guth declared:

It's hard to build models of inflation that don't lead to a multiverse. It's not impossible, so I think there's still certainly research that needs to be done. but evidence for inflation will be pushing us in the direction of taking the idea of a multiverse seriously

Adam Mann.

“Like a bit of froth on the crest of an ocean wave, our observable universe may be nothing more than a sliver sitting within the edge of a bubble that's constantly expanding into a higher dimension”

Paul Davies, The New York Times, "A Brief History of the Multiverse"

“Extreme multiverse explanations are therefore reminiscent of theological discussions. Indeed, invoking an infinity of unseen universes to explain the unusual features of the one we do see is just as ad hoc as invoking an unseen Creator. The multiverse theory may be dressed up in scientific language, but in essence it requires the same leap of faith”.

But this isn’t the only route to multiverse

Brian Greene's nine types

The American theoretical physicist and string theorist Brian Greene discussed nine types of multiverses:

Quilted

The quilted multiverse works only in an infinite universe. With an infinite amount of space, every possible event will occur an infinite number of times. However, the speed of light prevents us from being aware of these other identical areas.

Inflationary

The inflationary multiverse is composed of various pockets in which inflation fields collapse and form new universes.

Brane

The brane multiverse version postulates that our entire universe exists on a membrane (brane) which floats in a higher dimension or "bulk". In this bulk, there are other membranes with their own universes. These universes can interact with one another, and when they collide, the violence and energy produced is more than enough to give rise to a big bang. The branes float or drift near each other in the bulk, and every few trillion years, attracted by gravity or some other force we do not understand, collide and bang into each other. This repeated contact gives rise to multiple or "cyclic" big bangs. This particular hypothesis falls under the string theory umbrella as it requires extra spatial dimensions.

Cyclic

The cyclic multiverse has multiple branes that have collided, causing Big Bangs. The universes bounce back and pass through time until they are pulled back together and again collide, destroying the old contents and creating them anew.

Landscape

The landscape multiverse relies on string theory's Calabi–Yau spaces. Quantum fluctuations drop the shapes to a lower energy level, creating a pocket with a set of laws different from that of the surrounding space.

Quantum

The quantum multiverse creates a new universe when a diversion in events occurs, as in the many-worlds interpretation of quantum mechanics.

Holographic

The holographic multiverse is derived from the theory that the surface area of a space can encode the contents of the volume of the region.

Simulated

The simulated multiverse exists on complex computer systems that simulate entire universes.

Ultimate

The ultimate multiverse contains every mathematically possible universe under different laws of physics.

Cyclic theories

Main article: Cyclic model

In several theories, there is a series of infinite, self-sustaining cycles (for example, an eternity of Big Bangs, Big Crunches, and/or Big Freezes).

in terms of Kolmogorov complexity the proposed multiverse is simpler than a single idiosyncratic universe


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