BGV theorem

[shunyadragon]

Source: https://en.wikipedia.org/wiki/Penrose%E2%80%93Hawking_singularity_theorems

A singularity in solutions of the Einstein field equations is one of two things:

a situation where matter is forced to be compressed to a point (a space-like singularity)
a situation where certain light rays come from a region with infinite curvature (a time-like singularity)
Space-like singularities are a feature of non-rotating uncharged black-holes, while time-like singularities are those that occur in charged or rotating black hole exact solutions. Both of them have the property of geodesic incompleteness, in which either some light-path or some particle-path cannot be extended beyond a certain proper-time or affine-parameter (affine-parameter being the null analog of proper-time).

The Penrose theorem guarantees that some sort of geodesic incompleteness occurs inside any black hole whenever matter satisfies reasonable energy conditions (It does not hold for matter described by a super-field, i.e., the Dirac field). The energy condition required for the black-hole singularity theorem is weak: it says that light rays are always focused together by gravity, never drawn apart, and this holds whenever the energy of matter is non-negative.

Hawking's singularity theorem is for the whole universe, and works backwards in time: it guarantees that the (classical) Big Bang has infinite density.[1] This theorem is more restricted and only holds when matter obeys a stronger energy condition, called the dominant energy condition, in which the energy is larger than the pressure. All ordinary matter, with the exception of a vacuum expectation value of a scalar field, obeys this condition. During inflation, the universe violates the dominant energy condition, and it was initially argued (e.g. by Starobinsky[2]) that inflationary cosmologies could avoid the initial big-bang singularity. However, it has since been shown that inflationary cosmologies are still past-incomplete[3], and thus require physics other than inflation to describe the past boundary of the inflating region of spacetime.

It is still an open question whether (classical) general relativity predicts time-like singularities in the interior of realistic charged or rotating black holes, or whether these are artifacts of high-symmetry solutions and turn into spacelike singularities when perturbations are added.

Scientists later determined that this proposal implied something strange: that the multiverse is infinite, with endless, uncountable parallel universes existing alongside our own, Live Science previously reported. That wild situation presented a number of problems for science, most significantly that it rendered most basic scientific ideas about the multiverse impossible to test. (If there are infinitely many universes, then an experiment could make predictions about what the universe should look like — and there will be some universes out there that will match those predictions.)

"Hawking was not satisfied with this state of affairs," Hertog told Live Science in March. "'Let's try to tame the multiverse,' he told me a year ago. So, we set out to develop a method to transform the idea of a multiverse into a coherent, testable scientific framework."

© Copyright Original Source

Hawking considers the multiverse finite, one of an infinite number of multiverses within a Quantum World.

Personally, I vote for a reasonable foundation in science for the existence of the multi verse, and the Quantum World that contains them, and beyond that it gets foggy.

[shunyadragon]

Citations, please?

Blessings,
Lee

I believe I did. I am concerned about your reading skills as to whether you have read Vilenkin, Guth, and Borde references and papers, but nonetheless.

Source: https://www.scientificamerican.com/article/multiverse-the-case-for-parallel-universe/

Welcome to the Multiverse

By Alexander Vilenkin

The universe as we know it originated in a great explosion that we call the big bang. For nearly a century cosmologists have been studying the aftermath of this explosion: how the universe expanded and cooled down, and how galaxies were gradually pulled together by gravity. The nature of the bang itself has come into focus only relatively recently. It is the subject of the theory of inflation, which was developed in the early 1980s by Alan Guth, Andrei Linde and others, and has led to a radically new global view of the universe.

. . .

Another key aspect of the new worldview derives from string theory, which is at present our best candidate for the fundamental theory of nature. String theory admits an immense number of solutions describing bubble universes with diverse physical properties. The quantities we call constants of nature, such as the masses of elementary particles, Newton’s gravitational constant, and so on, take different values in different bubble types. Now combine this with the theory of inflation. Each bubble type has a certain probability to form in the inflating space. So inevitably, an unlimited number of bubbles of all possible types will be formed in the course of eternal inflation.

This picture of the universe, or multiverse, as it is called, explains the long-standing mystery of why the constants of nature appear to be fine-tuned for the emergence of life. The reason is that intelligent observers exist only in those rare bubbles in which, by pure chance, the constants happen to be just right for life to evolve. The rest of the multiverse remains barren, but no one is there to complain about that.

Some of my physicist colleagues find the multiverse theory alarming. Any theory in physics stands or falls depending on whether its predictions agree with the data. But how can we verify the existence of other bubble universes?

© Copyright Original Source

If this is not enough there are not a number of sources where Vilenkin, Guth and Borde discuss multi verses.

[shunyadragon]

I meant there is a proof, a theorem in this area of discussion.


I'm not sure what you mean here.


Yes, though the one universe we know of is expanding without limit.


Well, again, the BGV theorem provides a restriction on possible universe scenarios, it is not in itself a scenario.

Blessings,
Lee

You should no better, but I guess not, the authors of the bgv theorem did not propose a 'proof,' and you are deluded if you think they would remotely justify a Kalam argument.

[lee_merrill]

Your asking the wrong person. I personally do not believe that either expansion to the Quantum nothing is possible, or contraction where the point that dark matter no longer prevents contraction. Steinhardt could better answer your question.

Well, I shall no longer believe your claims if you cannot show how dark energy will be erased.

Hawking also believed that contraction is possible without time reversal, and explained it in the following summary:

So Hawking had evidence for his view, and now I shall wonder why most scientists believe in the Big Bang cosmology.

They pretty much all believe that they formed from singularities formed in the Quantum World of the multiverse.

Well, they don't, actually, the Big Bang is the prevailing view.

Source: Vilenkin and Ellis

But how can we verify the existence of other bubble universes? … This airing of ideas certainly hasn't led to a consensus among scientists...

© Copyright Original Source

So, no consensus with the multiverse...

... the authors of the bgv theorem did not propose a 'proof,' and you are deluded if you think they would remotely justify a Kalam argument.

Yet the theorem is a proof, and if the conditions and assumptions are met, it proves a beginning.

Blessings,
Lee

[shunyadragon]

Well, I shall no longer believe your claims if you cannot show how dark energy will be erased.

I shall no longer believe your claims if you cannot show where Hawkins is wrong. Again read Hawkins work carefully he does not erase dark matter.

Neither of us are competent to fully explain that Hawkins is wrong, but unfortunately you have a religious agenda, and think you know more than Velinkin, Guth, Borde, and Hawkins are wrong and selectively cite the bgv work to justify your agenda.

So Hawking had evidence for his view, and now I shall wonder why most scientists believe in the Big Bang cosmology.

Hawkin's view includes Big Bang cosmology, Can you read?!?!?!!?

Well, they don't, actually, the Big Bang is the prevailing view.
So, no consensus with the multiverse...

The dominant view is the existence of the multiverse, just as not all scientists support the Big Bang. So what?!?!?!

Yet the theorem is a proof, and if the conditions and assumptions are met, it proves a beginning.

Blessings,
Lee

Most scientists already believed in a temporal beginning based on Quantum Mechanics at least since Hawking. Big hairy deal! So what?

[lee_merrill]

I shall no longer believe your claims if you cannot show where Hawkins is wrong. Again read Hawkins work carefully he does not erase dark matter.

Well, we're here to discuss the BGV theorem! If you wish to discuss Hawking's views, you are welcome to create another thread.

Hawkin's view includes Big Bang cosmology, Can you read?!?!?!!?

Yes, but he extends it, these extensions are not part of the generally-accepted Big Bang view.

The dominant view is the existence of the multiverse...

No, there is no consensus on the multiverse, as cited above.

Most scientists already believed in a temporal beginning based on Quantum Mechanics at least since Hawking. Big hairy deal! So what?

So the BGV theorem is another indication that the universe had a beginning...

Blessings,
Lee

[Tassman]

Well, we're here to discuss the BGV theorem! If you wish to discuss Hawking's views, you are welcome to create another thread.

Hawking was an eminent physicist and his views are relevant to this discussion.

Yes, but he extends it, these extensions are not part of the generally-accepted Big Bang view.

There is no settled science re Big Bang theory.

No, there is no consensus on the multiverse, as cited above.

True, but it remains viable as an hypothesis.

https://www.space.com/18811-multiple...-theories.html

So the BGV theorem is another indication that the universe had a beginning...

It is an indication that this universe had a beginning.

[shunyadragon]

[QUOTE=lee_merrill;602031]Well, we're here to discuss the BGV theorem! If you wish to discuss Hawking's views, you are welcome to create another thread.

I do not believe that you can you can arbitrarily exclude Hawking and others from the dialogue, because Velinkin and the authors frequently cite Hawking and others in their bvg theorem.

Yes, but he extends it, these extensions are not part of the generally-accepted Big Bang view.

Not clear, Hawking clearly supports the beginning of the beginning of universes, and the singularity, and is probably one of the first to write a comprehensive paper on the singularity. It is more than apparent that Hawking supported both a beginning and a cyclic nature of universes.

No, there is no consensus on the multiverse, as cited above.

I claim dominant view and I stand by that claim, I will cite a list of those that endorse some form of multiverse. This where the dominant cutting edge of research in physics and cosmology is now. I will add a short list of those that oppose any sort of multiverse.

So the BGV theorem is another indication that the universe had a beginning...

Blessings,
Lee

According to the authors a temporal beginning in a greater multiverse cosmos.

[lee_merrill]

There is no settled science re Big Bang theory.

Some may wish it to be so, but the Big Bang has been verified in multiple ways, this is why scientists say the universe is 13.8 billion years old.

It is an indication that this universe had a beginning.

Yes, agreed.

Best wishes,
Lee

[lee_merrill]

I claim dominant view and I stand by that claim, I will cite a list of those that endorse some form of multiverse. This where the dominant cutting edge of research in physics and cosmology is now. I will add a short list of those that oppose any sort of multiverse.

Source: Space.com

The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today.

Source

© Copyright Original Source

Blessings,
Lee

[shunyadragon]

Source: Space.com

The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today.

Source

© Copyright Original Source

Blessings,
Lee

True, but does not address the problem you have of the multiverse being the dominant 'leading' view among the physicists and cosmologists.

[JimL]

Source: Space.com

The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today.

Source

© Copyright Original Source

Blessings,
Lee

Lee, we do not know that the universe began as a singularity, that notion was simply hypothetical, i.e. the idea that if we could reverse the inflation process then the universe would get smaller and smaller until it reached infinite size, that is a singularity, but there is nothing that actually backs that hypotheses up, nor do most phycisists take that view.

[shunyadragon]

The following is a partial list of the physicists and cosmologists that support and oppose the multiverse. More, of course, may be added to the lists, but the dominance is clear. I go with the qualifications and credentials of those that support the multiverse.

Scientists support in the multiverse – All PhDs in science and/or math, and published in peer reviewed journals in physics and cosmology
Alexander A. Antonov
Arvind Borde
Sean M. Carroll
Jean Dalibard
John Donoghue of the University of Massachusetts, Amherst.
Brian Greene
Ben Gripaios
Alan Guth
Stephan Hawking
Thomas Hertog Belgian cosmologist at KU Leuven University
Sabine Hossenfelder Frankfurt Institute for Advanced Studies in Germany
Dmitri Kazakov
Greg Kestin Harvard University,
Stéphane Lavignac
Hitoshi Murayama
Yasunori Nomura Berkley Center for Theoretical Physics.
Sir Martin Rees Britain’s astronomer royal
Veronica Sasnz
Tom Shanks of Durham University
Leonard Susskind of Stanford
Max Tegmmax
Alexander Vilenkin
David Wallace
Frank Wilczek

Clara Moskowitz - Senior editor American Scientific (not PhD.)

Belief in a cyclic universe from preexisting energy using string theory
Paul Steinhardt
Neil Turok

Oppose or extremely skeptical of a multiverse

Jim Baggott - DPhil in chemical physics at the University of Oxford
Luke A. Barnes
Bernard Carr
Paul Davies
George Ellis University of Cape Town
Dr Simon Friederich, a philosopher at the University of Groningen
David Gross of the University of California, Santa Barbara

[JimL]

The following is a partial list of the physicists and cosmologists that support and oppose the multiverse. More, of course, may be added to the lists, but the dominance is clear. I go with the qualifications and credentials of those that support the multiverse.

Scientists support in the multiverse – All PhDs in science and/or math, and published in peer reviewed journals in physics and cosmology
Alexander A. Antonov
Arvind Borde
Sean M. Carroll
Jean Dalibard
John Donoghue of the University of Massachusetts, Amherst.
Brian Greene
Ben Gripaios
Alan Guth
Stephan Hawking
Thomas Hertog Belgian cosmologist at KU Leuven University
Sabine Hossenfelder Frankfurt Institute for Advanced Studies in Germany
Dmitri Kazakov
Greg Kestin Harvard University,
Stéphane Lavignac
Hitoshi Murayama
Yasunori Nomura Berkley Center for Theoretical Physics.
Sir Martin Rees Britain’s astronomer royal
Veronica Sasnz
Tom Shanks of Durham University
Leonard Susskind of Stanford
Max Tegmmax
Alexander Vilenkin
David Wallace
Frank Wilczek

Clara Moskowitz - Senior editor American Scientific (not PhD.)

Belief in a cyclic universe from preexisting energy using string theory
Paul Steinhardt
Neil Turok

Oppose or extremely skeptical of a multiverse

Jim Baggott - DPhil in chemical physics at the University of Oxford
Luke A. Barnes
Bernard Carr
Paul Davies
George Ellis University of Cape Town
Dr Simon Friederich, a philosopher at the University of Groningen
David Gross of the University of California, Santa Barbara

I lean toward a multiverse as well. It makes sense. Highly unlikely that it happened only once, or that it was created out of nothing, so it probably happens all the time in the same way that everything inside this universe happens all the time.

[Tassman]

Some may wish it to be so, but the Big Bang has been verified in multiple ways, this is why scientists say the universe is 13.8 billion years old.

This universe is generally thought to be 13.8 billion years old. But, as shunya keeps telling you, “this universe” may well be but one of an infinite number of universes each arising via its own “Big Bang”. Very many scientists believe this to be the case.