Ask MetaFilter questions tagged with cosmology

Is that red shift in your pocket...

sundri — Tue, 08 Dec 2009 13:24:40 -0800

Is that red shift in your pocket... O.k., this bugs me every time I see an article that states something along the lines of "hubble looks way back in time!" or " [we are] spotting galaxies that existed just 600 million years or so after the big bang"?

Since I am assuming we can not observe our own matter, what is it we are looking at?

I have been operating under the assumption that the matter we observe, who's light is reaching us 600 million years later, is matter that is more or less moving in a direction that is -- again more or less -- opposite of ours. A lot of time is spent talking about the when of it, but not the what.

Or did I miss something in cosmology for dummies....

Can the Universe hold all of mathematics?

DU — Tue, 23 Jun 2009 05:33:29 -0800

Can the Universe hold all of mathematics? First assumption: The universe is finite in size and time. (Size, OK, but time is undetermined AFAIK.)

Second assumption: There is some scale below which information cannot be packed. At the planck scale, say. Put another way, there is a maximum information density to the universe.

These two assumptions imply that there is some maximum amount of information storable in the universe.

However, it is easy to prove on a number of fronts that mathematics has an infinite amount of information. The reals, for instance. Or, if that's not "information" in a strict sense, consider Godel's Incompleteness Theorem. It basically says that no matter how big the axiom list, there's always another one you can add.

Where is this information stored if not the universe?

Running this past an acquaintance of mine, he first suggested that while space was quantized, time wasn't. I countered by noting that General Relativity doesn't differentiate between the two.

His second attempt to wiggle free was to cloud the issue with a discussion of "creating" vs "discovering" mathematics. However, I think this is a red herring. Whether one creates or discovers, the information exists and had to come from somewhere. (There's a Conservation of Information principle, right? Entropy?)

Let's say I had a box. When I crank the handle, it applies Godel's method and pops out a new mathematical axiom that can't be proved from the existing list. *crank* P=NP! *crank* Riemann! *crank* Etc! I furiously scribble all these down at the tiniest scale possible.

At some point, the universe will be completely packed with information. I crank the handle one more time. And....?

Now that I think about it, how can such a box exist? There's much more information coming out of that box than the space(time) inside can hold. Is "raw information" leaking into the box from the universe? My understanding was that an "information generator" such as this box couldn't produce more information than it was "made of". That helpfully prevents the box from filling the universe up (whew!) but does not explain where all the information of mathematics is coming from.

Is expansion slowing down galaxies?

knave — Tue, 16 Jun 2009 11:09:14 -0800

Does expansion of the universe decelerate orbits of planets and/or rotation of galaxies? My understanding of the expansion of the universe is that, essentially, new space is appearing everywhere. I've heard it said that gravity holds solar systems and galaxies together, and they don't expand or grow in size from this inflation. However, the space between galaxies does grow, because gravity at these distances can't compete with the expansion. (Correct me if any of this is wrong.)

That leaves me wondering... If gravity is overcoming the small amount of inflation within solar systems and galaxies, then it must come at a cost. Gravity doesn't introduce new energy into a system, so my intuition says correcting the orbit of a body to its original distance must come at a cost of orbital speed.

Is this thinking correct, or am I missing something?

Unusual music for beautiful space images? No electronic space music, please?

Jennifer S. — Tue, 24 Feb 2009 13:00:56 -0800

Attention music lovers: I’m looking for music to accompany a gorgeous planetarium show about philosophy, cosmology, perception and the known universe. Know any good instrumental music that’d making an interesting and unusual choice to accompany images of distant space? Something Carnatic, Persian…beyond airy space music or Philip Glass?

***

A colleague is doing a talk inside a sort of planetarium (a GeoDome, actually) with a program that models the known, observable universe to its limit.

Here’s some Flickr sets of the visuals accompanying the talk.

He’s currently using airy electronic music which works fine. But I wonder if there isn’t another approach.

I’ve heard that Sergei Eisenstein was inspired to juxtapose images in his movies by seeing Japanese ideograms. An ideogram showing a knife and a heart together, for instance, does not mean murder or violence, but sorrow.

I would like to try to find music that creates a similar effect, and provides a richer context for my colleague’s ideas.

I first thought of Carnatic music, with its ties to ancient Hindu religion, so much more in touch with cosmic timeframes than Western religions. But most of the instrumental Carnatic violin music I’ve found has changes in tempo that don’t make it a good choice for background music.

Ideally, the music should be instrumental, relatively unobtrusive and not have jarring percussion/dissonance/changes in tempo/etc. that would distract listeners significantly away from the speaker. Also, ideally, it’d be downloadable and in the public domain or created by an artist willing to let it be used.

Any ideas? Love to have them! Thanks!

Is it possible to be bad at math and understand the structure of the universe?

diogenes — Wed, 20 Aug 2008 09:47:40 -0800

Is it possible to be bad at math and understand the structure of the universe? A recent question about the structure of the universe got me thinking about my own attempts to understand these ideas. I'm fascinated by cosmology, but I suck at math. It's a frustrating combination ;) I read cosmology books (like Carl Sagan) and listen to astronomy podcasts, and I feel like I'm gaining some understanding. Am I just fooling myself? Is it only the physicists and mathematicians who truly understand the structure of the universe?

To put it another way, most of my understanding is based on analogies provided by people who understand the math. Are these analogies so partial and flawed as to be useless?

How strange it is to be anything at all?

mjewkes — Sat, 12 Jul 2008 08:41:36 -0800

Where did the universe come from in the first place? Is there any framework, scientific, philosophic, or religious that addresses where the universe came from in the first place? i.e. where god, the singularity, or the infinite cycle of birth and death arose/came from?

To inifinity and beyond!

tomcochrane — Thu, 03 Jul 2008 06:13:21 -0800

What are some topics in astronomy or cosmology that you find fascinating and mind blowing? I recently took an introductory cosmology course at the university I attend, and have taken a couple astronomy courses before that. I've also been reading up on the topics a little, and I find everything fascinating.

Previously, I asked the hive mind about what math topics they thought were really cool. That thread brought about many very interesting answers. So now, with the upcoming 'switching on' of the Large Hadron Collider there must be lots of MeFites out there who find this as interesting as I do!

What blows your mind about astronomy or cosmology?

Λ

plexi — Wed, 12 Mar 2008 14:28:22 -0800

How is the universe 156 billion light years across if it is only 13.7 billion years old?

What are some philsophical or cosmological frameworks that regard our universe as a living entity?

beegull — Fri, 07 Dec 2007 10:54:40 -0800

Is there an existing philosophical or cosmological model that regards the universe as a living thing with the observed patterns and "laws" of the universe being a reflection of an inherent model analogous to the genetic models of living things as we know them? My own uneducated philosophical meanderings have led me to this idea and I am wondering about developed theories or philosophies that follow similar lines. First of all, think of living things as self-contained models of the universe that include the reproduction of that model. For us, our inherent model is contained in our genes, and that model predicts an environment (where the environment includes the body of the living thing) that will result in reproduction of that model, which will in turn result in reproduction of that model, and so on. The accuracy of those predictions, and the degree to which the inherent model reflects the events that occur over the course of the organisms life, dictates success as a living thing.

Now imagine that the universe is itself a living organism and we are part of its "body". Features of this universe are dictated by a universal model that itself has developed as a result of a natural selection of universes. Just as we develop conscious models, through science, that parallel the models inherent in our genes (as we figure out what genes do, and sometimes why), so might we develop conscious models that parallel the inherent models that underly a universe that has inherited those models from "universal ancestors".

I have read a bit about a "Darwinian cosmology" with black holes as the sort of universal gametes, and life and consciousness as a side effect. What I am wondering about is if others have developed the idea that consciousness, and our drive to understand and build a model of our universe is itself the mechanism for reproducing the universe. Now I know this is where it starts to sound all new agey and anthropocentric, but the idea here is that an understanding of the underlying model of our universe and the technology that comes with that may eventually result in the birth of the next generation of our universe. So the underlying model of our own universe itself predicts consciousness as the eventual means of reproduction of the universe, in the same way that our genes predict gametes and all of our biological apparatus as the eventual way to reproduce themselves.

I realize that the predictions that come out of this idea are hardly testable at the moment, since it would require some way to "observe" other universes and maybe to eventually witness the birth of a new universe. I also realize that this still leaves the existence of a still underlying environment with its patterns and problems that are themselves modeled by the universal model. And so on, and so on. Again, I am just curious if any Mefites know about philosophies or cosmologies that may have explored a similar idea.

Where did the big bang happen?

wigglin — Wed, 29 Aug 2007 22:37:02 -0800

If wanted to arrive at the point in space where the big bang occurred, in which direction should I start traveling?

good physics lectures

dydecker — Mon, 04 Jun 2007 05:28:21 -0800

Are there any great lecturers/public speakers in the realms of cosmology, astronomy and physics? I'm looking for speakers who can do what Dawkins or Dennett do for evolutionary biology, by which I mean make really difficult and mindbending stuff easy for the layman to understand. And be articulate. Obv. there is Feynman...anyone else?

Also any links to podcasts/mp3s would be appreciated.

A Problem of Scale: Halfway in size between an atom and the universe

0bvious — Sun, 18 Feb 2007 16:10:04 -0800

"A human is halfway in size between an atom and the known universe"... This is a paraphrased quote I have come across several times. I like it. Who said it first? How true is it in the most literal sense? And, finally, what errors arrive in postulating a universe, or an atom, which can be measured AT ALL from our singular, relativistic, perspective? I found this quote from Cosmic Evolution which further complicates the whole relative size issue:

"Roughly halfway in size between an atom and a human, the amoeba has poor awareness and coordination. It generally responds only at the point stimulated, communicating the information sluggishly through the rest of its body. Although amoebas have developed a crude nervous system, living things that aspire to be more agile—and smarter—surely need quicker internal reactions." - link

Kind of sets another stage from which to view this question.

I also found this quote from Holmes Rolston which further complicates things:

"The human world stands about midway between the infinitesimal and the immense. The size of our planet is near the geometric mean of the size of the known universe and the size of the atom. The mass of a human being is the geometric mean of the mass of the earth and the mass of a proton. A person contains about 10²⁸ atoms, more atoms than there are stars in the universe. Such considerations yield perhaps only a relative location. Still, questions of place and proportion arise." - link

Who first made this often used statement? My earlier questions still stand :-)

Thanks...

Is the Universe made of information?

grumblebee — Thu, 15 Feb 2007 07:05:25 -0800

Can you help a reasonably smart layperson (who is not very good at math) understand how the word "information" is used in physics? I'm talking about when "information" is NOT used to describe data exchanged between sentient beings. I keep hearing about how "the universe is information" or "the universe is a quantum computer."

I get how some natural systems, like DNA, contain data which nature uses to control some sort of process. Is this the core idea?

And I know that each age has described the universe in terms of its dominant technology (steam or whatever), and so we use information, because this is the "information age," but I also know that -- metaphor or not -- seeing the universe as information is yielding some profound ideas.

I've even read a book or two on the subject, but these books always seem to take off from the point-of-view that the universe IS information. I feel like I'm not getting to the heart of what this means.

What's Your Cosmology

goalyeehah — Mon, 21 Aug 2006 17:43:24 -0800

I am looking for sources that give the weight of the earth, volume of all the oceans, total acreage on the planet, total current population and guestimated total weight of said population. I am doing personal research for a question that came to me last week. I would like to find how much space does the current population of the planet occupy?

one small step for mefi - the moon's spin and orbit

humuhumu — Wed, 25 Jan 2006 23:19:07 -0800

Is it cosmic coincidence that the moon spins once on its axis in exactly the same time it takes to orbit the earth (hence the dark side we never see from earth) or is there some reason why this should be more likely?

Is the universe finite?

painquale — Wed, 12 Jan 2005 12:27:41 -0800

Can anyone recommend any good recent articles or papers on whether the universe is infinite or finite? I've heard that scientists suspect that the universe is flat, which lends credence to the infinite-universe hypothesis. I've decided I don't know enough about this. Nothing too technical, please, though I'd prefer something more complex than an article from a newspaper science section.