Quickfire Cosmo Qs

Is cosmology a science? Why?

P.S. -- ordered your book. :-)

Hi Tom :)

:) but all is sciences Zeeya .All is Inside a science.Determinism determinism when it tells to rationalism that Copenaghen school is objective like all proportional causes and effects after all :) cosmology is a science...

best

I will, Zeeya. This subject is a tough one, and I congratulate you for taking it on.

(Hi, Steve)

Thank you for this thread! One thing I've wondered is what precisely physicists mean when they talk about the first second after the big bang, or the first minute. Naïvely perhaps, it seems that these intervals would not be even remotely close to "Earth seconds," given that shortly after the big bang, the energy-density of the universe was immensely greater, with time dilated accordingly, from our perspective in a much lower-density region of spacetime. Sorry if this is not a quick query!

Not quick but fun Karl!

It's really simple Karl! There are no definitive answers. I've thought about the primal instant and the first few moments for years now, and it's like the proverbial rabbit hole that just keeps getting deeper the farther down you go. I've heard folks like Gerard 't Hooft and Lee Smolin expound somewhat on in it in their lectures, and even talked with them afterward, but there is so much to learn! In short; the answer differs, depending on which scenario your working theory favors, in terms of the dimensionality of the universe and so on. Or there may have been more than one start, as with "Out of the white hole.." where our present-day cosmos arises from a black hole in an earlier 5-d universe.

Your query was actually one of my driving concerns, for the questions I asked of Tevian Dray at the end of GR21. Certain mathematical complications come into play, whenever we deal with the very smallest levels of scale, and to an even greater degree (or unavoidably) when we crank back the clock to the first instant. This makes non-commutative and then non-associative geometry dominant as we approach the limit. So the number of dimensions and degrees of freedom appear to be greater. But paradoxically; the folks in CDT and Quantum Einstein Gravity get good results (matching our cosmos) assuming that spacetime is initially 2-d evolving to 4-d smoothly, with fractal transitions.

More later,

Jonathan

Part of the reason is this..

Yes there are extreme energy densities and gradients. Relativity becomes undefined where there are no structures existing independently, that can move relative to one another - because the universe is too small. Time, space, and energy, all flow away from the Planck-scale domain, because there is no effective angle of approach past the first instant. It is that way by definition. And the onset of inflation does create a time-dilation effect for observers wrt adjoining regions of spacetime - assuming inflation is the scenario you favor.

Andy Beckwith's essay touched on a possibility I like, that it's a minimum extent of time that gets things going - something from nothing. I talked about this with him, and I wrote something suggestive of it years ago, in my very first FQXi essay. But if time is primal; perhaps once there is a certain amount of it, space, energy, and matter, must emerge. This is precisely what Beckwith's result appears to indicate.

The era of geometrogenesis is somewhat a mystery to Physics. We know that it happened. What happens once particle production begins can be reverse-engineered to an extent, using the data about specific energies and transitions from particle accelerators and so on. The transition time for various energy binding processes, that create various sub-atomic particles, sets the time scale. And the half-life duration of particles sets other time base parameters at that juncture.

All the Best,

Jonathan

Zeeya,

I have read the first chapter ("God's Billboard: the Cosmic Microwave Background") and I can already see that it will take a long time to finish your book. That is my highest compliment.

First, I was compelled to take Anthony Zee's Fearful Symmetry off my shelf after 30 years, for another read. I enjoyed it so much, and I may buy the new edition you mentioned. And then I was reminded how much I "hated" John Horgan's The End of Science; I hated it so much I read it three times in a row (and will probably read it again, too, concurrent with Zee and Merali). I heartily disagreed with Horgan's premise ("ironic science") yet I was enchanted by the dialogue, and delighted to get a look at the private musings of great scientists.

I may "hate" your book for the same reasons. Though Horgan is not a believer, as you are, you share the same fascination with the limits of knowledge.

Suppose we had no secrets from one another--our most intimate thoughts and deeds completely transparent to every human on Earth. Would we know ourselves as individuals?

So far as we do know, we come complete; i.e., with a complete consciousness--not to say that we can't grow or change--but we seem to be born already individualized, with built-in hidden compartments for secret thoughts, and infinite potential for interaction.

Compare to computers--who have a consciousness of their own--and limited potential for interaction. We might make exceptions for such machines as IBM's Deep Blue; nevertheless, we have to tell it how to interact, and though we may be amazed to find that it creates incomprehensible algorithms of its own, one need be reminded of poet Delmore Schwartz: "I am a book I neither read nor wrote." The same poet wrote, "Existentialism means that no one else can take a bath for you."

If every thought has the potential to be free and independent, where does it begin and end? - with God, with irony? With artificial intelligence?

The best we can do, it seems, is to enjoy the journey wherever it takes us. Thanks for taking me with you! We may yet be able to realize the full import of Jacob Bronowski's observation, "All science is the search for unity in hidden likenesses."

All Best,

Tom

A few questions that are pertinent to another that I might post later.

If something falls into a black hole, at what speed does it cross the event horizon? I note that an outside observer sees time slow down for a falling object and never sees the object meet the event horizon.

If something falls into a black hole on a path not directly to the singularity, ie not perpendicular to the horizon, at what angle does it enter the event horizon (note max v in normal space is c.) Not perpendicular?

When two black holes merge, what paths do the two associated singularities take once the two event horizons meet?

If a massive object (one with mass) is accelerated to c, it's mass increases. Does this mass increase result in a higher gravitational attraction due to the object?