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Vilenkin On Cosmic Inflation And Multiverse


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Monday night I went to a lecture at the Amer. Mus. of Natural History by physicist/cosmologist Alexander Vilenkin of Tufts U. Vilenkin spoke on the theory of cosmic inflation. He is one of its primary theorists.

 

Standard Big Bang theory models what happened after the Big Bang, the beginning of our universe some 13.8 billion years ago.  Cosmic Inflation theory models what led up to and just at the Big Bang.

BAA in particular deserves my thanks for having brought up these topics and for having posted a link which linked an announcement of the lecture.

Much of it was understandable to a layman like me, though parts were over my head. I took notes and link them at the bottom. I invite those with more expertise than mine to suggest corrections, if there are clear errors in what I tried to copy from his talk.


I'll just offer a few points that pertain to topics of theological import.

 

1- Ours is one of a huge number of universes that "bubble up" out of high energy false vacuums 

2 - the set of all of them is called the Multiverse

3 - String Theory suggests there are 10500 different vacuums with different values of natural constants, so a huge number of universes are likely

4 - a universe that allows life must have protons and neutrons of the size that these have in our universe, a very unlikely occurrence.  It's fallacious to suppose that our universe must have been fine-tuned for life by an intelligent designer, though.  And given the number of universes, we expect some of them will allow life.

5 - Vilenkin thinks the multiverse is future-eternal, but he says he and others have proved mathematically that it's not past-eternal - it had a beginning 

(a controversial topic, though - cf. this:

http://www.technologyreview.com/view/427722/mathematics-of-eternity-prove-the-universe-must-have-had-a-beginning/)

6 - Vilenkin argues that the multiverse may have begun without having been caused.  I did not understand his argument for this.

7 - although, as BAA informed us, the results of BICEP2, which were at first announced as proof of cosmic inflation, may have been caused by interstellar dust, Vilenkin thinks there is enough other circumstantial evidence to support the theory of cosmic inflation.

 

Anyway, I will welcome any and all correction and further education on these fascinating topics!

Alexander Vilenkin on cosmology Am Mus Nat Hist.doc

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Ummm... sorry, F.  sad.png

 

The MIT link comes up as, 'Page Not Found' and the .doc file refuses to open on my computer. "Word experienced a problem trying to open this file."

 

????

 

 

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Ummm... sorry, F.  sad.png

 

The MIT link comes up as, 'Page Not Found' and the .doc file refuses to open on my computer. "Word experienced a problem trying to open this file."

 

????

I'm sorry, don't know what's wrong with the links.  I just went to the MIT page and found the article again.  I'll try linking again:

 

http://www.technologyreview.com/view/427722/mathematics-of-eternity-prove-the-universe-must-have-had-a-beginning/

 

It's entitled "Mathematics of Eternity Prove that the Universe Must Have Had a Beginning" and dated April 24, 2012.

 

Although my notes are 3 1/2 typed pages, I'll try pasting them directly into this post:

 

Alexander Vilenkin, Tufts Univ.  “The Universe and Beyond.”  American Mus. of Natural History, June 9, 2014

 

my notes as well as I could take them down in the dim light and with my lack of background knowledge.

 

Standard Big Bang theory.

   1 minute – nuclei

   1 million years – atoms

   10 billion years – galaxies

   14 billion years (roughly) - now

Initial “fireball” mostly uniform but not completely so.  Denser regions attracted more matter, formed galaxies.

This model supported by observational data, pretty sure it’s correct.  Galaxies moving away, observed amounts of lithium (?) etc. as predicted.

But smoking gun is background radiation, afterglow of the Big Bang

 

Unanswered questions include accounting for:

universe’s high temperature

expansion

substantial homogeneity

some inhomogeneities (lack of homogeneity), tiny quantum fluctuations

 

Theory of Cosmic Inflation addresses the above questions (Guth and Linde)

 

Key role played by false vacuum.  A vacuum has all particles of radiation removed;  it is not a radical nothing.  Has properties, different energy states for different kinds of vacua.

Different types of vacua have different sorts of particles in them.  Our vacuum has small, non-zero energy in sum.  Very high vacua should exist with large energy density (and other properties I couldn’t get down).

 

Most important property of a false vacuum for theory of inflation is repulsive gravity.  Einstein said gravity is a function of mass and pressure, not just of mass.  False vacuum has negative pressure so it has negative gravity, i.e. repels.  Also unstable, decays into fireballs of particles.

 

Theory of Inflations explains how the Big Bang occurred.  Guth assumed the early universe was in a state of false vacuum.  Repulsive gravity caused universe to expand.  Doubled in size every 10-38 second.  Then false vacuum decayed, energy created fireball which continued to expand.  The END of inflation is the Big Bang.  So inflation explains features of the BB, provides theory of the BB, while BB theory only addresses aftermath of the explosion.  Theory of Inflation explains universe’s high temperature, expansion (from repulsive gravity of false vacuum), homogeneity.  Mulhanov and Chibisov explained how there was also some lack of homogeneity, for small fluctuations create differences in density.

 

   After theory of inflation was proposed, some evidence followed from cosmic radiation measured by satellites.  Satellites measured intensity of radiation.  Found to be fairly uniform but some deviations, which back up the existence of small inhomogeneities predicted by the theory.  This evidence provides picture of the universe in its youth.

 

Theory of Inflation says space on a large scale is almost flat.  Appears flat because of vast size, as Earth does to us.  Astronomers found a result that agreed with the theory [i didn’t understand this part].

 

BICEP2 team w/ telescope in Antarctica.  They said they detected gravitational waves from inflation, like ripples on surface of a pool.  They seemed to fit theory’s predictions of fluctuations.  Announced March 17, 2014.  Actually they didn’t find gravitational waves directly but rather, a pattern of polarization.  Other things, however, like interstellar dust can produce same pattern.  Vilenkin thinks other evidence is persuasive that inflation is “on a pretty firm footing.”

 

Beyond our horizon.  Theory says that though inflation ended in our universe, overall it never ends.  There will be other big bangs and can have been big bangs earlier than ours.  “Inflation is eternal” into the future.  It doesn’t end everywhere at once.

 

Multiverse.  False vacuum decays through bubble nucleation, decays like boiling water, bubble universes within the false vacuum.  “An unlimited number of bubbles will be formed in the course of eternal inflation.”

 

How do we know there are other bubbles, since we can’t travel outside of ours to them?  No hard tests.  Indirect tests have been made.  Bubble collision could leave an imprint on the cosmic background radiation, a circular region where intensity to polarization is higher.  People are trying to analyze data but no guarantee we’ll ever observe a bubble collision.  As in a trial with no witnesses, when lawyer has to get circumstantial, indirect evidence, so too here. 

 

Different bubbles may have different values from our constants of nature.  Our constants appear to be fine-tuned for life.  E.g. if you decrease the mass of neutron by 1%, no atoms.  Increase mass of neutron by1%, have only hydrogen.  This seems to suggest Intelligent Design.  But another view is that there is a huge number of universes.  Some few will have these constants, and intelligent creatures will evolve in them and marvel at fine tuning!

 

String Theory suggests how to unite quantum mechanics and theory of gravitation.  It suggests there are 10500 different vacua with different values of natural constants.  Bubble universes of all types.  We can live only in bio-friendly bubbles.

 

Multiverse – Inflation produces huge number of universes, a small fraction of which will support life.  So this explains why some have natural constants needed for life.  This theory of multiverse not tested.  Any checking cannot be by observation but only by statistical predictions.  In multiverse picture, neutrino mass different in different bubbles.  But question to ask is, what would typical observer see.

     Predicted magnitude of the energy density of our vacuum is confirmed by the data.  Steven Weinberg predicted it in 1987.  Astronomers later detected non-zero energy of our vacuum.  “Our first evidence for the multiverse?”

 

End of our universe.  A negative energy bubble will eventually nucleate within our horizon.  It will engulf entire visible universe and turn all objects into some alien form of matter.  The multiverse will go on but our local part end.  This end will not be foreseen because it will come at the speed of light, so can’t be observed before it arrives.

 

Inflation is eternal into the future but Borde, Guth and Vilenkin’s theorem says inflation must have had a beginning – a geometric proof.  No answer to “What happened before inflation?”

Beginning may have been spontaneous, from nothing.  Most probable initial state:  a tiny, closed universe filled with a high-energy false vacuum.  In such a close universe, numbers will be zero [i didn’t understand this part]. Nothing prevents a creation.

But there will be many if there can be one.  This is intial condition for inflation – microscopic universe, spontaneous.  [i didn’t understand this part very well.]

 

“No time before. No cause required.  but the laws of physics should be there.”  Compare St. Augustine saying similar in Confessions.  Meaningless to ask about “before” or cause.  Atoms decay randomly, beginning can be random.

 

Since laws of physics are used to describe creation as expansion, it’s as if the laws of physics were “already there.” 

 

Question/Answer time.  Did not last long!

 

Inflation took place before and during our bubble.  Dark energy is vacuum energy in our universe.  Special theory of relativity would apply to all the universes.

 

One question: Is “nothing” possible?  A: physicists by “nothing” mean a state in which there is no matter.  The state nevertheless can have properties.

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If something in my notes of Vilenkin's lecture seems incorrect, the first hypothesis would be, ficino's lack of background knowledge made him screw up in taking down the note!

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Here's the Mithani & Vilenkin paper.  I can't evaluate it.

 

 

http://arxiv.org/pdf/1204.4658v1.pdf

 

 

A rejoinder to their paper was written by Leonard Susskind.  He concludes that there is a beginning, but that in any kind of inflating cosmology, the odds are almost infinitely stacked in favor of the beginning's being so far in the past that it is effectively at minus infinity.

 

 

http://arxiv.org/pdf/1204.5385.pdf

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Ok, thanks F.

 

I've got all the links now.

Get back to this thread once I've read and digested.

 

Thanks,

 

BAA.

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Ummm... sorry, F.  sad.png

 

The MIT link comes up as, 'Page Not Found' and the .doc file refuses to open on my computer. "Word experienced a problem trying to open this file."

 

????

I'm sorry, don't know what's wrong with the links.  I just went to the MIT page and found the article again.  I'll try linking again:

 

http://www.technologyreview.com/view/427722/mathematics-of-eternity-prove-the-universe-must-have-had-a-beginning/

 

It's entitled "Mathematics of Eternity Prove that the Universe Must Have Had a Beginning" and dated April 24, 2012.

 

Although my notes are 3 1/2 typed pages, I'll try pasting them directly into this post:

 

Alexander Vilenkin, Tufts Univ.  “The Universe and Beyond.”  American Mus. of Natural History, June 9, 2014

 

my notes as well as I could take them down in the dim light and with my lack of background knowledge.

 

Standard Big Bang theory.  

   1 minute – nuclei

   1 million years – atoms

   10 billion years – galaxies

   14 billion years (roughly) - now

Initial “fireball” mostly uniform but not completely so.  Denser regions attracted more matter, formed galaxies.

This model supported by observational data, pretty sure it’s correct.  Galaxies moving away, observed amounts of lithium (?) etc. as predicted.

But smoking gun is background radiation, afterglow of the Big Bang

 

Unanswered questions include accounting for:

universe’s high temperature

expansion

substantial homogeneity

some inhomogeneities (lack of homogeneity), tiny quantum fluctuations

 

Theory of Cosmic Inflation addresses the above questions (Guth and Linde)

 

Key role played by false vacuum.  A vacuum has all particles of radiation removed;  it is not a radical nothing.  Has properties, different energy states for different kinds of vacua.

Different types of vacua have different sorts of particles in them.  Our vacuum has small, non-zero energy in sum.  Very high vacua should exist with large energy density (and other properties I couldn’t get down).

 

Most important property of a false vacuum for theory of inflation is repulsive gravity.  Einstein said gravity is a function of mass and pressure, not just of mass.  False vacuum has negative pressure so it has negative gravity, i.e. repels.  Also unstable, decays into fireballs of particles.

 

Theory of Inflations explains how the Big Bang occurred. 

 

Yes.  This is the hot Big Bang, which applies only to our 'pocket' universe -  a volume at least a thousand times larger than the 94 billion light-year diameter of the observable universe.

 

Guth assumed the early universe was in a state of false vacuum.  Repulsive gravity caused universe to expand.  Doubled in size every 10-38 second.  Then false vacuum decayed, energy created fireball which continued to expand.  The END of inflation is the Big Bang. 

 

Yes.  The end of Inflation in our pocket universe is the hot Big Bang we now have evidence for.  Whatever preceded that is purely speculative.  Since Inflation totally erases any evidence of any preceding conditions, it's impossible for us to know if our pocket universe is the very 1st one to inflate like this or 10499th.

 

So inflation explains features of the BB, provides theory of the BB, while BB theory only addresses aftermath of the explosion. 

 

Yes.  Only the aftermath.  As mentioned above, whatever came before is unknowable.  However, two more things ARE knowable.  First, once it begins, inflation continues forever, at an exponentially-increasing rate.  Second, the minimum duration that it's been happening is 13.82 billion years - the calculated age of our universe.  This is working on the (unfounded) assumption that our pocket universe really was the very first to be inflated.  Applying the Copernican and Cosmological principles to this question yields the result that we are NOT special and therefore we do NOT have the status of first.

 

Theory of Inflation explains universe’s high temperature, expansion (from repulsive gravity of false vacuum), homogeneity.  Mulhanov and Chibisov explained how there was also some lack of homogeneity, for small fluctuations create differences in density.

 

   After theory of inflation was proposed, some evidence followed from cosmic radiation measured by satellites.  Satellites measured intensity of radiation.  Found to be fairly uniform but some deviations, which back up the existence of small inhomogeneities predicted by the theory.  This evidence provides picture of the universe in its youth.

 

Theory of Inflation says space on a large scale is almost flat.  Appears flat because of vast size, as Earth does to us.  Astronomers found a result that agreed with the theory [i didn’t understand this part].

 

It's to do with Friedmann universes.  I can explain if you want.

 

BICEP2 team w/ telescope in Antarctica.  They said they detected gravitational waves from inflation, like ripples on surface of a pool.  They seemed to fit theory’s predictions of fluctuations.  Announced March 17, 2014.  Actually they didn’t find gravitational waves directly but rather, a pattern of polarization.  Other things, however, like interstellar dust can produce same pattern.  Vilenkin thinks other evidence is persuasive that inflation is “on a pretty firm footing.”

 

Yes.  Even if BICEP2 is a bust, there are still several very strong lines of evidence that imply that inflation did happen.  Also, there are other teams working on finding said polarization pattern in the CMB.  Wait and see.

 

Beyond our horizon.  Theory says that though inflation ended in our universe, overall it never ends.  There will be other big bangs and can have been big bangs earlier than ours.  “Inflation is eternal” into the future.  It doesn’t end everywhere at once.

 

Yes.  At at an absolute bare minimum - inflation's been happening (elsewhere) for at least 13.82 billion years.

 

Multiverse.  False vacuum decays through bubble nucleation, decays like boiling water, bubble universes within the false vacuum.  “An unlimited number of bubbles will be formed in the course of eternal inflation.”

 

This is Max Tegmark's Level 2 multiverse. http://en.wikipedia.org/wiki/Multiverse

 

How do we know there are other bubbles, since we can’t travel outside of ours to them?  No hard tests.  Indirect tests have been made.  Bubble collision could leave an imprint on the cosmic background radiation, a circular region where intensity to polarization is higher.  People are trying to analyze data but no guarantee we’ll ever observe a bubble collision.  As in a trial with no witnesses, when lawyer has to get circumstantial, indirect evidence, so too here. 

 

 

http://en.wikipedia.org/wiki/Laura_Mersini-Houghton

She proposes that detection of other bubbles may be possible and has had mixed success with the verification of her predictions.

 

Different bubbles may have different values from our constants of nature.  Our constants appear to be fine-tuned for life.  E.g. if you decrease the mass of neutron by 1%, no atoms.  Increase mass of neutron by1%, have only hydrogen.  This seems to suggest Intelligent Design.  But another view is that there is a huge number of universes.  Some few will have these constants, and intelligent creatures will evolve in them and marvel at fine tuning!

 

http://en.wikipedia.org/wiki/Anthropic_principle

 

String Theory suggests how to unite quantum mechanics and theory of gravitation.  It suggests there are 10500 different vacua with different values of natural constants.  Bubble universes of all types.  We can live only in bio-friendly bubbles.

 

Multiverse – Inflation produces huge number of universes, a small fraction of which will support life.  So this explains why some have natural constants needed for life.  This theory of multiverse not tested.  Any checking cannot be by observation but only by statistical predictions.  In multiverse picture, neutrino mass different in different bubbles.  But question to ask is, what would typical observer see.

     Predicted magnitude of the energy density of our vacuum is confirmed by the data.  Steven Weinberg predicted it in 1987.  Astronomers later detected non-zero energy of our vacuum.  “Our first evidence for the multiverse?”

 

End of our universe.  A negative energy bubble will eventually nucleate within our horizon.  It will engulf entire visible universe and turn all objects into some alien form of matter.  The multiverse will go on but our local part end.  This end will not be foreseen because it will come at the speed of light, so can’t be observed before it arrives.

 

Look behind you, F!  wink.png

 

Inflation is eternal into the future but Borde, Guth and Vilenkin’s theorem says inflation must have had a beginning – a geometric proof.  No answer to “What happened before inflation?”

 

Cue WLC and OrdinaryClay!  

But they fail to factor the Copernican and Cosmological principles into their argument.  Also, the Finite and Infinite Replication Paradoxes make mincemeat of the idea of human identity.  http://www.rationalskepticism.org/philosophy/afterlife-under-physicalism-t21843.html (See post # 2, by Teuton.)  Why would God want to fill up heaven with zillions of exact duplicates of SteveBennett or IronHorse?  :(

 

Beginning may have been spontaneous, from nothing.  Most probable initial state:  a tiny, closed universe filled with a high-energy false vacuum.  In such a close universe, numbers will be zero [i didn’t understand this part]. Nothing prevents a creation.

But there will be many if there can be one.  This is intial condition for inflation – microscopic universe, spontaneous.  [i didn’t understand this part very well.]

 

99.99999999999999999999% of the human race doesn't either.

 

“No time before. No cause required.  but the laws of physics should be there.”  Compare St. Augustine saying similar in Confessions.  Meaningless to ask about “before” or cause.  Atoms decay randomly, beginning can be random.

 

Since laws of physics are used to describe creation as expansion, it’s as if the laws of physics were “already there.” 

 

Question/Answer time.  Did not last long!

 

Inflation took place before and during our bubble.  Dark energy is vacuum energy in our universe.  Special theory of relativity would apply to all the universes.

 

One question: Is “nothing” possible?  A: physicists by “nothing” mean a state in which there is no matter.  The state nevertheless can have properties.

 

 

Good work, btw!

 

goodjob.gif

 

Thanks for this.

 

BAA

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Why would God want to fill up heaven with zillions of exact duplicates of SteveBennett or IronHorse?

Um, I guess so there will be zillions more heavenly mouths to sing "Pass it On"?

 

Thank you for your responses and analysis, BAA!

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Wow. Some really heady stuff here. I'll have to set aside some time to read through it properly. Thanks ficino and BAA!

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Why would God want to fill up heaven with zillions of exact duplicates of SteveBennett or IronHorse?

Um, I guess so there will be zillions more heavenly mouths to sing "Pass it On"?

 

Thank you for your responses and analysis, BAA!

 

 

Not a problem, F!

 

Thanks for being there and getting this stuff down for us!  smile.png

 

I'll check those two papers out (as best I can) asap.

The Christians (lead by WLC) tried to exploit the subtleties and loose wording of Borde, Guth and Vilenkin's 1994 and 2003 papers (see references # 2 and 3 of the Mithani & Vilenkin paper), claiming that since a past-eternal multiverse is proven to be impossible...Biblegod therefore did it!  They'll probably try and make the same kind of capital with this latest one too.

 

Therefore I'll see what gives and get back to this thread when I have something worth reporting.

 

Susskind's paper works the other way.  It's a gift for our side!  yellow.gif

 

(Much) Later.

 

BAA

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Thanks for pointing me here F! I'll check out your attachment as soon as I can.

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  • 3 weeks later...

Sorry for being late to the party.  A few thoughts.

 

 - Most of the points here are a review of the current state of inflationary cosmology, but it sounds like it was a good review and an important summary to give at any talk aimed at a general audience.

 

 - The issue of the multiverse not being past-eternal is interesting.  I've never seen a paper on this, but I would greatly appreciate any links if you happened to see references in his talk!

 

So about the BICEP2 result...as you know BICEP2 is a microwave detector, much like Planck and WMAP before it.  Basically BICEP2 was trying to detect B-mode polarization imprinted on the CMB by gravitational waves triggered by inflation in the early universe.  My PhD thesis was on imprints of extragalactic background light on gamma-ray energy spectra, and while these two problems are very different I'm at least vaguely familiar with the experimental techniques involved in analyzing astrophysical spectra.  It's actually a bit easier for microwaves from an experimentalist's standpoint; the signals aren't nearly as hard to detect as gamma-rays are.  But there's still the issue of foreground subtraction: genuine signals which you simply aren't interested in from a scientific standpoint.  In order to subtract emission from dust (I assume dust from other galaxies), they had to use a map of the cosmic microwave background.  They didn't have a published map available, so they used a PDF file of a slide from a conference, and extracted the strength of emission at each point in the sky.  As Dr. Spergel (who put forth the alternate explanation of the B-mode polarization in the CMB) says, it's a risky thing to do.  Some researchers once extracted data from a PDF conference proceeding put out by the collaboration I was working with, and many of my collaborators freaked out because they were claiming gamma-ray detection that we were pretty sure wasn't there.  You really don't want to claim to know an experiment's data better than the people who built the experiment and analyzed its data!

 

In my mind this pretty much invalidates the analysis; I know my advisor would never have let me publish this kind of result.  That said, there's a relatively simple solution: obtain the Planck CMB skymap and redo the background subtraction!  That will eliminate this obvious source of error, and bolster any results from BICEP2.

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 - The issue of the multiverse not being past-eternal is interesting.  I've never seen a paper on this, but I would greatly appreciate any links if you happened to see references in his talk!

 

 

Thanks for your input, Bhim.  BTW - I thought you were still working on your Ph.D.  You've finished it?  Congratulations, that's great!

 

As to the links to papers about the question, whether the multiverse is past-eternal, see the two in my #6 above.

 

Cheers, ficino

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Sorry for being late to the party.  A few thoughts.

 

 - Most of the points here are a review of the current state of inflationary cosmology, but it sounds like it was a good review and an important summary to give at any talk aimed at a general audience.

 

 - The issue of the multiverse not being past-eternal is interesting.  I've never seen a paper on this, but I would greatly appreciate any links if you happened to see references in his talk!

 

So about the BICEP2 result...as you know BICEP2 is a microwave detector, much like Planck and WMAP before it.  Basically BICEP2 was trying to detect B-mode polarization imprinted on the CMB by gravitational waves triggered by inflation in the early universe.  My PhD thesis was on imprints of extragalactic background light on gamma-ray energy spectra, and while these two problems are very different I'm at least vaguely familiar with the experimental techniques involved in analyzing astrophysical spectra.  It's actually a bit easier for microwaves from an experimentalist's standpoint; the signals aren't nearly as hard to detect as gamma-rays are.  But there's still the issue of foreground subtraction: genuine signals which you simply aren't interested in from a scientific standpoint.  In order to subtract emission from dust (I assume dust from other galaxies), they had to use a map of the cosmic microwave background.  They didn't have a published map available, so they used a PDF file of a slide from a conference, and extracted the strength of emission at each point in the sky.  As Dr. Spergel (who put forth the alternate explanation of the B-mode polarization in the CMB) says, it's a risky thing to do.  Some researchers once extracted data from a PDF conference proceeding put out by the collaboration I was working with, and many of my collaborators freaked out because they were claiming gamma-ray detection that we were pretty sure wasn't there.  You really don't want to claim to know an experiment's data better than the people who built the experiment and analyzed its data!

 

In my mind this pretty much invalidates the analysis; I know my advisor would never have let me publish this kind of result.  That said, there's a relatively simple solution: obtain the Planck CMB skymap and redo the background subtraction!  That will eliminate this obvious source of error, and bolster any results from BICEP2.

 

Yes, that's pretty much my (totally amateur) understanding of things too, Bhim.

 

Foreground dusty contamination of background B-mode polarization signals in the BICEP2 data.

Subtraction of the foreground contaminants shouldn't have be done from a PDF file by the BICEP team (but as I read the rumors circulating in the blogosphere) the Planck team (who apparently hold enough high-quality data to do a proper subtraction) didn't want to release that info to anyone else, before they were ready - which will be some time this October / November.

 

So BICEP were stuck in a bind.  

Should they have just sat on what they thought was a bona fide discovery and wait for Planck to pip them to the post?

Or should they do the best the could with what they had to hand (that PDF file data) and hope for the best?

 

That's not a call I'd like to have to make.  sad.png

 

Thanks,

 

BAA

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  • 3 weeks later...

 

Thanks for your input, Bhim.  BTW - I thought you were still working on your Ph.D.  You've finished it?  Congratulations, that's great!

 

 

As to the links to papers about the question, whether the multiverse is past-eternal, see the two in my #6 above.

 

Cheers, ficino

 

 

Thank you!  Yeah, I finished last November just before Thanksgiving.  It's quite a relief to no longer be considered a student (as I'm sure was your experience as well).

 

 

 

 

Yes, that's pretty much my (totally amateur) understanding of things too, Bhim.

 

Foreground dusty contamination of background B-mode polarization signals in the BICEP2 data.

Subtraction of the foreground contaminants shouldn't have be done from a PDF file by the BICEP team (but as I read the rumors circulating in the blogosphere) the Planck team (who apparently hold enough high-quality data to do a proper subtraction) didn't want to release that info to anyone else, before they were ready - which will be some time this October / November.

 

So BICEP were stuck in a bind.  

Should they have just sat on what they thought was a bona fide discovery and wait for Planck to pip them to the post?

Or should they do the best the could with what they had to hand (that PDF file data) and hope for the best?

 

That's not a call I'd like to have to make.  sad.png

 

Thanks,

 

BAA

 

 

Yes, I think this quite accurately describes the situation.

 

I will say that from a career standpoint it was probably the right decision.  You can publish your analysis technique along with the finding, and be careful about how strongly you state your thesis.  That way if the discovery is later confirmed, your collaboration gets credit.  If not, your credibility perhaps isn't hurt too badly since you only made as strong a claim as your data collection technique warranted.

 

...having said that, I read the abstract of their paper, and perhaps the claim was stated a bit too strongly.  At least the superluminal neutrino "detection" by the Opera collaboration was not accompanied by any speculation on implications for fundamental physics.

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  • 2 weeks later...

Thanks for sharing this. I don't have the math background to parse everything. But I do always enjoy reading about the concepts and theories. Had it not been for religion's influence on my life, I'd have become a physicist or an astronomer.

Never too late. I saw some older students in my department. And FYI grad school is free.

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Maybe Bhim means that many grad students are awarded a full-tuition fellowship and then something else, like a teaching assistantship, or a lab section, or research to do, so that their studies are funded.  This is not always true in the humanities.  For example, a former student of mine is in a Ph.D. program in art history.  She says that many of the students have to come up with their own money, and then the number of jobs at the end is very limited.

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Yeah, the costs suck. You may be paying your year's worth of tuition per credit for grad school plus books and all the free work they get out of you, and that's cheap compared to some programmes.

 

I went back to school as a more "mature" adult who had spent well over a decade working in my original field. I'm not going to go into my age; however, I had an EMS student who was in his late 50's and was a recently retired electrical engineer. He's now in nursing school and doing well. I've also had new students in their 60's that did just fine. Don't write yourself off. I actually had a long discussion with one of my chemistry professors about grad school and age was a concern. She said there are in fact many people in their mid to late thirties to fourties and even fifties going into STEM fields (I will admit that what I'm doing is debatable regarding affixing the STEM label however). Also, many people in my cohort are older folks who are already well established in their fields. I will say my capacity for abuse is compromised compared to how I was in my late teens and early twenties. I remember working my military job, working as an EMT on the side and going to school full time. No sleep with maximum punishment. Currently, I work a full time job with bankers hours during the week and a weekend or two requirement each month. This means most of my work is at night and on the weekends. I end up pulling allnighters every so often but typically get a few hours of sleep a night then crash when I can on the weekends I have off. Not optimal but in another year or so it should end. I've had no help and have to pay for everything out of pocket. This also means that I do not qualify for much in the way of scholarships. There certainly are not the financial resources available to people who do Masters Degrees. However, a doctoral programme may be different as you may have grant money, teaching assistant and paid teaching duties and even paid research and/or lab opportunities. In some sense, going from undergrad into a doctoral programme may be better financially. You'll want to really research the programme, faculty and advisors before applying. I'm not so sure about doctoral programmes so much, but I had to take the GRE and score above certain thresholds. Some forms of the GRE are focus specific such as biochemistry. I believe a physics specific exam exists.

 

Good luck. It sucks when you are older but I've never been happier and I'm actually doing something that interests me.

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I see I've generated some interest. Let me explain further. As Ficino mentioned, grad school in the humanities is rarely free, and even in more applied subjects like engineering many people pay their own way. But in the natural sciences, research grants pay for most people's grad students, and so assistanceships abound. At my department not one person paid tuition. Among my collaborators elsewhere in the US and abroad, I knew almost no one who had to pay. In fact, we all got money on top of the tuition waiver. It wasn't a lot, but t it paid the bills. So if you're going into physics and astronomy, don't worry about accumulating more student debt.

 

PS. Human, the oldest student in my department was in his late 40s and had two kids.

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To echo what Bhim has said:  I went back to school at the age of 35 and took a degree in biotechnology.  I was, by far, not the oldest student in my program.  There were a few who had retired from other professions and just wanted to learn something new.

 

I interned in an immunological research lab at UNCC and the Principle Investigator suggested I stay on with the lab and pursue graduate studies, as I could have my tuition and other expenditures paid for through the lab's grant funding.  Had I not had a wife and newborn to support, I would have gladly taken him up on his offer.

 

I still try to stay current on the latest research, but that's about all I can do for now.  One day, though, I'd like to have letters following my name.

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