AAI 2009: Darwin's Legacy

[quadz]

Salutations!

Just got back from AAI '09, which was essentially a symposium on the topic of Darwin's legacy, with talks given by eminent biologists, cosmologists, philosophers, and various other scientists and thinkers.

My mind is still reeling from the talk Lawrence Krauss gave on Saturday morning.  Krauss is a cosmologist / theoretical physicist, and his talk, while not locally Darwin-related, centered on the long view of the fate of the universe itself, and also touched on theoretical limits on the observational capabilities of future evolving species.

(I believe most of these talks will eventually be uploaded to the web somewhere.  They were definitely being videoed.)

What I loved about so many of the scientific talks, was the focus on not just recounting the latest discoveries, but rather illuminating the evidence and methodology used to make the discoveries.  They did a pretty good job putting it into layman's terms... even though, as Lawrence Krauss pointed out, he always has to "lie a little" when converting the math into words.  The math being the only way to truly describe the problem.  But the words were indeed compelling.

So it wasn't just, "we now believe the universe is X years old", but rather, "we're now able to estimate the age of the universe to four decimal places, and here's how we're calculating it, and the calculations agree with all of the following separate theories, ..."

A couple things that blew my mind in Krauss' talk, were related to mass resulting from quantum vacuum energy, and the implications of a "flat" universe.

Unfortunately I didn't take notes, so this is from memory, and I hope I don't butcher it too badly.

Krauss showed an animation computed from a mathematical model of quantum vacuum energy, showing this 'foam' of virtual particles continuously blobbing in and out of existence... but the part that was new to me, is apparently these transient quantum particles make up 90% of the mass of a proton!?

So for any physical object we're familiar with, including our own bodies, 90% of our mass comes from this foaming chaos of transient virtual particles, appearing and disappearing within the vast empty spaces inside the subatomic particles our bodies are composed of!

  *  *  *

And as for the "flat" universe... There has long been the question of whether we are living in a closed, flat, or open universe.  These terms don't pertain to squished dimensions, but rather the ultimate fate of the universe: a closed universe will eventually cease expanding and collapse back in on itself, resulting in the Big Crunch; an open universe will keep expanding forever; and a flat universe is similar to an open universe, except that it is perfectly balanced--it will neither expand forever, nor eventually collapse....

But, the important aspect of a flat universe in Krauss' talk, was that some crucial energy/density factor was zero (I apologize again for not taking notes.)  Krauss said something to the effect that gravity can have negative energy, and that when energies are balanced out such as in a flat universe, this has a remarkable property that the whole thing--(i.e. Big Bang)--can have arisen from a quantum vacuum energy fluctuation, without there having to have been any pre-existing energy borrowed to form that initial event.

I've always wondered where the apparently enormous energy that could have produced the Big Bang might have come from in the first place.  But apparently, according to the laws of quantum physics--which are reputedly the most accuractely confirmable theories of any that we have discovered--if we are in a flat universe, then there didn't need to be any preexisting energy to have been present in order for the Big Bang to occur.

Krauss then illustrated various means by which our universe has been measured, revealing that it does indeed appear to be flat...

  *  *  *

One other equally mind blowing part of Krauss' talk, concerned what future species evolving on planets around stars 100_000_000_000 years or so in the future will be able to see. . .

Apparently by then, each individual galaxy will be accelerating away from each other galaxy at more than the speed of light (relatively) such that observers within any given galaxy, will find the night sky to be devoid of any other galaxies -- such that whoever these future entities are, they could apply the scientific method, and (re)-discover most of what we currently have discovered, except that they would think their galaxy would be the center of the universe--because nothing--neither other galaxies nor the cosmic background radiation--would be available anymore for them to be able to observe otherwise.

So, sadly, such future species evolving on planets orbiting future stars, will, according to theory, not have any means of realizing their galaxy is not the center of the universe...

 * * *

Many other awesome talks as well, including several presentations detailing the overwhelming evidence for evolution, from various mutually-supporting lines of evidence, including swatting down creationist claims like 'the appearance of life violates thermodynamics' (no, cf. the sun), and, 'we've never unearthed a species branching point in the fossil record' (yes we have, several times), and examples of 'irreducible complexity' etc.

 * * *

A kick-ass weekend!

Regards,

[[BTF] Reflex]

Sounds like fun,


 On the flat or closed universe,  I had read something about that being measured out to 13 or 14 billion light years and shown flat.
But still held a possibility of curvature, if the universe were big enough to make our measurement appear straight.

Kinda like measuring a football field on Earth would make the world look flat

[QwazyWabbit]

Lots of points touched upon. Sounds like a nice weekend, surely better than the vegetative state of housekeeping an chores I found myself in.

Not sure I can accept a FTL expansion theory though. If c is the ultimate speed limit then entropy ought to override long before expansion rates are that high.

I find the whole expansion business to be a trifle odd to begin with. If the universe (space-time) is expanding, then all material objects should be expanding proportionately with the underlying fabric. Therefore, our yardsticks ought to be incapable of detecting the expansion. Our present understanding of expansion comes from E. Hubble's observation that the farther an object (galaxies, generally) is away from us, the greater the red shift in it's spectrum. Of course, Hubble's determination of "distance" came from quasars and pulsars and "brightness" measurements so red shift is a sort of self-referrential scale of distance. One thing I'd like to see discussed is the simple gravitational red shift. If light must "escape" a gravity well then there must be a gravitational red shift for all emitted light from that source. The farther away the source is, the further the light must "escape". (Do photons really have a zero rest mass?) The longer light travels, the more energy it must lose in the process. One might say, quantum mechanics aside, the older a photon is, the longer it's wavelength will be. The most ancient photons we have detected in the universe are from the cosmic background radiation remnant of the big bang and these are in the microwave range. Or are they really from the big bang? If spacetime is infinite in extent then there will be a limit to the observable universe and that limit will be a function of our detectors to "see" the longest wavelength photons. These would be radio wavelengths, meters or kilometers long, lost in the noise of our technology emissions and our own Earth's magnetic fields. The "age" of the universe and consequently the "distance" we can see will be a function of the wavelengths we use.

[quadz]

Not sure I can accept a FTL expansion theory though. If c is the ultimate speed limit then entropy ought to override long before expansion rates are that high.

I find the whole expansion business to be a trifle odd to begin with. If the universe (space-time) is expanding, then all material objects should be expanding proportionately with the underlying fabric. Therefore, our yardsticks ought to be incapable of detecting the expansion.

That's something I did wonder about.

There was an open mic afterward for a question/answer period.  I wanted to ask about FTL expansion, but, I felt I was too newbie to formulate my question intelligently.

Too bad ya weren't there, it would have been fun to hear some discussion on that issue.


Regards,

quadz

[[BTF]Defiant!]

Not sure I can accept a FTL expansion theory though. If c is the ultimate speed limit then entropy ought to override long before expansion rates are that high.

I don't understand if entropy is related to the constant expansion of the fabric of the universe.  And, the velocity expansion isn't limited to the speed of light, because it isn't inertia, or gravity, or another force.  Reasonable?

I find the whole expansion business to be a trifle odd to begin with. If the universe (space-time) is expanding, then all material objects should be expanding proportionately with the underlying fabric. Therefore, our yardsticks ought to be incapable of detecting the expansion.

The two ends of your wood yardstick are expanding according the expansion of the universe; but, local forces so enormously overpower it, that it may not be measurable locally.   The expansion of the universe is not changing the definition of a yard.  If it were, t would be truly imperceptible locally and universally.

A bit like me standing on a rubber tightrope the width of the United States.  Consider it expanding at all points at an end-to-end rate of 50 km/hour.  Measured between my feet it would be imperceptibly moving.  Bad analogy I suppose since it would be very perceptible movement relative to the ground near the ends.  But maybe that helps reenforce the point, that space isn't made of material limited by expansion rates.


On a personal note, I attend the Origins conference early this year at Arizona State.  It had a stunning set of attendees: Hawking (who was sick and only sent a video), Pinker, Dawkins, Venter, Krauss, Greene, Johanson, a shovel-full of Nobel-laureates, and public figures like Neil Tyson, Carl Segan's daughter, etc..

[QwazyWabbit]

Quadz, I would have enjoyed seeing that discussion as well, and probably felt too noob to have been bold enough to ask a question also. Even when I was young and bright enough at one time to question Kip Thorne about gravity waves over dinner.

Def,

General relativity (or is it special, I can never keep them straight) (actually, special is for uniform motion) holds that c cannot be exceeded by any material object. Therefore, a galaxy cannot be "accelerated" to a relative velocity wrt to another observer under any conditions. But if space-time itself is expanding then the "velocity" between points could exceed c under the right conditions in this case. I would disagree, if c is constant and inviolate then space-time itself cannot expand faster than c. The forces on a material object are not a factor if the space-time manifold is expanding and presumably the distances between atoms in that space-time manifold is expanding with it.

By yardsticks, I did not literally mean wooden or a yardstick but more like benchmarks. We cannot measure space-time except by measuring distance and time and both of these quantities are relativistic. A second is so much distance in space-time and a linear dimension in space-time is so many wavelengths of light or so many seconds at the speed of light. Einstein tells is the speed of light is constant for all frames of reference and there is no such thing as a "special" or inertial frame of reference therefore our measurement of time and distance is interlocked with the speed of light. This was his solution to the Lorentz transformations. So, we can conclude that "an object" will expand and contract with relative motion in space-time and we must compute distance transforms according to the relative motion of the frames of reference even when those frames are being carried by space-time itself.

If you and I were separated by 10 million light years and we measured the red shift of the light emitted by our neighbor stars, I would conclude you were receding from me at some velocity and you would conclude I was receding from you at the same velocity but neither of us could conclude who was "moving" faster. My point is that if we could say "we both are stationary within the spacetime fabric" then the relative motion is due purely to spacetime and not to any acceleration of you or me. If spacetime is inflating then the atomic distances of our molecules should be inflating at the same proportions and we should be unable to see spacetime inflating even though we observe the red shift. I believe this was the crux of Einstein's cosmological constant. This was the fudge factor that made the yardsticks longer as spacetime expanded.

[[BTF]Defiant!]

Agree with all.  I was reacting to your comments earlier, which you then addressed in your last post. 

Of course, I don't know either way, but I also don't understand a reason why it violates what we know.

[quadz]

On a personal note, I attend the Origins conference early this year at Arizona State.  It had a stunning set of attendees: Hawking (who was sick and only sent a video), Pinker, Dawkins, Venter, Krauss, Greene, Johanson, a shovel-full of Nobel-laureates, and public figures like Neil Tyson, Carl Segan's daughter, etc..

Nice... I was able to watch a bunch of those on youtube.

Speaking of which, the videos from AAI 2009 have been posted... Here's Lawrence Krauss' talk from the event:

  Lawrence Krauss - A Universe From Nothing
 
http://www.youtube.com/watch?v=7ImvlS8PLIo

[quadz]

Not sure I can accept a FTL expansion theory though. If c is the ultimate speed limit then entropy ought to override long before expansion rates are that high.

I find the whole expansion business to be a trifle odd to begin with. If the universe (space-time) is expanding, then all material objects should be expanding proportionately with the underlying fabric. Therefore, our yardsticks ought to be incapable of detecting the expansion.

That's something I did wonder about.

There was an open mic afterward for a question/answer period.  I wanted to ask about FTL expansion, but, I felt I was too newbie to formulate my question intelligently.

I had an opportunity to ask Dr. Krauss about this yesterday.

His reply, to the best of my recollection: The 'empty' space between the galaxies is expanding.  The galaxies themselves are at rest (relativistically) within their local space-time.

I asked if this was the same kind of expansion as that proposed during the inflationary period after the big bang.  His reply, again parahprased: Yes, we are currently in a second period (phase?) of inflation.

Some follow-up questions I would have liked to have asked, but which didn't occur to me until I got back to my hotel room:

 - How are we able to detect that it's the empty space between the galaxies that's expanding, as opposed to the galaxies themselves moving away from one another without any inflation being involved?

 - It sounds as though the galaxies are each within their own 'bubble' of local space-time, unaffected by the inflation occurring in the empty space between them?  If so, why are they unaffected?  (Something to do with gravity?)

 - Alternately, if inflation is occurring uniformly throughout space, even within the galaxies themselves, then shouldn't we be unable to detect it?  (Note, I seem to recall Lawrence Krauss addressing this in one of his talks: If inflation were occurring uniformly, then even our telesopes would be expanding right along with everything else, and we wouldn't be able to detect it. So I presume based on this recollection that inflation must not be occurring uniformly.)


Anyway, I'm grateful to Dr. Krauss for graciously entertaining my newbie questions, especially after he'd just spent a clearly frustrating hour on hold with the airlines trying to resolve some sort of mixed up plane reservation.

Also, he said he's currently writing a book based on his 2009 "A Universe From Nothing" lecture, which is expected to be published in March.  It'll cover topics such as the above in more detail.


Regards,

quadz

[yahoo]

cool stuff.

Everyday mankind continues to learn bout new things most specially about the universe. Jsut decades ago the possibility of a black hole was not taken seriously. As of the present, there are evidences that at every heart of a galaxy there is a super massive blackhole that keeps the stellar cluster together.

Likewise, the cohesion of the stars in a galaxy and the clustering of galaxies could not be possible with sheer gravity alone but can be more or less attributed by dark matter.

Now, there is growing evidence what was originally thought as the end of the universe "the big crunch"  was wrong and more probably this universe would end in a big chill. stars and galaxies are moving away from each other , hence eons later even particle of matters would rip themselves apart (Dark Energy).

In my end, I would like to believe that  eventually everything would cease expanding and would contract and the whole new cycle of creation would start again. Its more fascinating to thing that this universe we live in is just one of the many universes that had come and gone.