Find Out About the Future of Science 446
Science magazine writer Charles Seife has written a new book, Alpha and Omega: The Search for the Beginning and End of the Universe. According to Publishers Weekly, Charles claims, "Scientists...now know how the universe will end and are on the brink of understanding its beginning. Their findings will be among the greatest triumphs of science, even towering above the deciphering of the human genome." A brave statement! Charles is happy to answer your questions about ongoing research that is busily revealing the basic nature of life, the universe, and everything in a serious (as opposed to humorous) sense, so ask away. One question per post, please. We'll post the answers as soon as we get them beck.
Re:I've been doing some thinking about this lately (Score:5, Informative)
Intelligent Design, a recent theory that has gained enough respect from the scientific community
Woah, stop right there.
It's proponents claim that it has respect in the scientific community. You will find scientists who like the idea. But the fact is, so far as peer review and confirming experiments and the general scientific community, it is not considered really a viable theory. It's certainly not any competition for evolution amonst the sceintific community at all.
The proponents' PR claims it is, but that's just the PR.
See, for example, http://www.phys.cwru.edu/~krauss/inteloped.html [cwru.edu].
-Rob
Which end do we know will happen now? (Score:5, Informative)
Possible scenarios include:
This fell out of favour a while back, when the need for a flat universe became apparent. In this scenario, the universe's espansion halts and it re-collapses. Once it was thought that this would involve time running backwards/entropy reversal during the crunch phase, but it was later shown that scenarios with increasing entropy also existed. There was much speculation about whether the universe would "bounce" after it crunched, forming a new expanding universe.
This scenario was popular when we'd made a detailed enough survey to know that that amount of bright matter in the universe was far too low to counteract the expansion. It fell out of favour when our estimates of the amount of dark matter got better.
In this scenario, the universe keeps expanding quickly, and all matter that isn't gravitationally bound into clusters is separated by vast empty regions of space. As the universe's expansion represents the expansion of space itself, sufficiently large gravitationally bound clusters might still be disrupted, due to distances changing internally. Galaxies burn out as stars exhaust their fuel, stellar corpses eventually merge with each other and with the central black hole, which finally decays after a mind-bogglingly huge length of time.
This scenario assumes that the amount of matter - light and dark - is perfectly balanced with the expansion of the universe. There was strong circumstantial evidence for a scenario like this, due to the fact that deviations from flatness amplify over time and that our universe was still _roughly_ flat - but the linchpin was a variety of models for the early universe - and the big bang - that required the universe to be flat. More detailed measurements of the amount of dark matter in the universe seemed to be consistent with this model.
In this scenario, the rate of expansion slows, approaching zero as time goes to infinity. Distance still goes to infinity as time goes to infinity, but not as rapidly. From a local point of view this looks a lot like Whimper Version 1.
This model arose when evidence for dark energy was discovered by observations of distant parts of the universe. In this model, the universe started out as flat, but a weak repulsive effect comes into play that causes expansion to accelerate. The effect is small enough that we haven't diverged that greatly from flatness yet, but in the end, it'll be Whimper Version 1 all over again. This is one of the two currently plausible scenarios.
This model was the result of closer examination of the scalar field models used to drive inflation in the early universe. In the inflationary model - which itself was proposed to solve the problem of the universe's matter distribution being so smooth - a "scalar field" existed in the early universe that permeated space and caused vast amounts of new space to be created. In the original version of the inflationary model, this scalar field's effects died out shortly after the big bang. A later model, however, proposed that the field was not cancelled everywhere - in some regions of the universe, constructive interference would cause it to be strong enough for inflation to continue.
Thus, we have a model where the universe looks mostly like our own, except for regions where it "buds" to form new universes. This process continues forever. This is the second scenario currently considered plausible (with the scalar field taking on the role of "dark energy").
This is the model proposed by
Universes on multiple membranes. (Score:3, Informative)
While it's common to call the universe "everything," it's really just "everything we can sense or extrapolate." There very very well might be a much much larger "macroverse" out there--but to get to this point, we're firmly out of science (which is a search for knowledge) and into theory--also known as "religion", "dreaming", and "half-assed speculation."
Firstly, you apparently have been misinformed about the definition of the word "theory". An idea that is proposed without evidence is a "conjecture". An idea that matches a lot of the available information and has no major contradictions with observations - in other words, a plausible conjecture - is a "hypothesis". To change categories a bit, a "model" is a set of equations that attempts to accurately describe the behavior of some apsect of the universe. They are often the subject of hypotheses - e.g., you could hypothesize that the "whimper version 3" model is an accurate description of the universe. The model and the hypothesis are two different types of object.
A "theory" is the last hypothesis standing after all hypothesis have been subjected to very rigorous experimental tests. If after every attempt you can make to tear it down, a given hypothesis remains the best explanation available for a phenomenon or set of observations, then it graduates to the "theory" category.
Calling "half-assed speculation" "theory" or vice-versa is very far from correct.
Now, on to the multiple membranes model. The main problem I have with it is that it supposes some higher-dimensional space in which the membranes are embedded, and supposes that interaction can occur through this space. Proposing larger spaces for embedding as a mathematical crutch is fine as long as they don't have a material effect on the observable universe, but if there's a fourth spatial direction that forces can propagate in, why do we only observe three directions? If things can be pulled and pushed across this gap, why don't particles and stars and whatnot move freely in this direction? What forces them to be bound into membranes?
This model makes a number of propositions along these lines for which simpler alternate explanations exist (e.g. for dark matter, that there are enough particles present that don't interact via EM to have substantial gravitational effect - we already have several candidates for part of this detected by other methods [the neutrino flavours]).
As far as I can tell, this multiple-membrane model gets attention because of similarities in name (and only name) to the "brane" model for superstrings (which proposes that particles are p-dimensional membranes instead of one-dimensional objects). The superstring / brane models avoid the observational problems of extra spatial dimensions by making them too small to have impact on the macroscopic world (and their microscopic impact is exactly that required to make vibrating string modes match up with the particles we observe). Completely different beasts.
Re:Universe's container (Score:5, Informative)
(0,1)
ta da! In case you can't read the notation, that's all the real numbers between 0 and 1 but excluding 0 and 1 themselves. There are infinitely many of them, but they are bounded by 0 and 1 (a container). Also note: although 0 and 1 were used in the definition of this interval, they are not actually a part of it.
Perhaps the real problem is that infinity is a hard concept. I don't think we humans can ever truly understand it. But we can still throw it around in math and physics problems and come up with interesting results.
Re:Dark Matter (Score:5, Informative)
Dark Matter, as an esoteric, non-euclidian form of matter, is still, IMO, nothing more than the late 20th century equivalent of the luminiferous aether of the 19th century, and merely a convenient algorythmic placeholder, until proven otherwise.
Actually, things turn out to work a little differently.
First of all, neutrino oscillation experiments confirm pretty convincingly that neutrinos do have mass. Rough bounds on the amount of mass have already been placed. The best numbers to date say that massive neutrinos can account for some, but far from all, of the dark matter effects observed.
Second of all, brown dwarfs and other "massive compact halo objects" would be baryonic dark matter - and there are good arguments for most of the dark matter being non-baryonic. A summary of some of these arguments can be found here [princeton.edu] (it's multiple pages; follow the links).
Third of all, I have not heard a convincing argument that EM effects in stars relate to the dark matter problem. There is one reseaercher who keeps publishing papers about the galaxy acting as a dynamo, with large-scale EM effects determining structure, but many holes have been poked in this proposed model (a few came up in previous slashot articles).
There are some questions about the galactic magnetic field (why it has one as strong as it does, if I recall correctly), but the observed field has negligeable effect on the movements of stars within the galaxy.
In summary, there really does seem to be some kind of exotic dark matter present in large quantity, and we already have several candidates for components of it.
Re:Universe's container (Score:5, Informative)
From what I remember, people have made similar "spear carrying" measurements which indicate that seem to indicate that the "surface" of space is curved
Similar spear-carrying measurements have been made, yes. Well, not eactly, but measurements that can determine the curvature of spacetime.
It is curved in the Solar System. That's the effect of the Sun's gravity. That can give you, for instance, the gravitational lensing effect first observed for the Sun be Eddington back in the begininng of the 20th Century.
The Universe as a whole, though, has a flat geometry; measurements have been made that show this. (OK, there's a small uncertainty, so it might be curved a little one way or the other; and, we've only measured the observable Universe, so there could be a curvature we can't see because we're looking at too small of a piece of it (think of trying to measure the curvature of the Earth by looking at a 10'x10' patch of ground).) Here's one site which describes some of the experiments that have been done (and precision has been improved since these):
http://www.lbl.gov/Science-Articles/Archive/boomer ang-sidebar.html [lbl.gov]
Your memory from your modern physics class is, at the least, outdated.... 1999 or thereabouts was the first time that a measurement was made of the Universe's geometry that really gained widespread acceptance, in that it was the first time the measurement had been done well enough and precisely enough that it was believable.
-Rob
Re:What is the next paradigm shift? (Score:3, Informative)
> paradigm shifts to answer current outstanding questions? It seems to me,
> at least, that maybe there aren't any, and today's scientists are left working
> harder and harder simply to add a few significant digits to existing theories.
> What are your thoughts?
Whether it classifies as paradigm shift or not, I can not say, but we have a bunch of extremely important problems to solve (most or all of which somehow revolve around the concept of mass... quite interesting). Off the top of my head:
1) We havent yet arrived at any fundamental explanation of gravity.
2) Particles in the current Standard Model of Particle Physics can't have mass, as mass terms violate some fundamental symmetries. The so-called Higgs mechanism might provide a way around this, but introduces more problems itself.
3) Dark matter. Is it some kind of so far unknown particle lying around out there?
4) The CP violation (i.e. the asymmetry between matter and anti-matter) within the Standard Model is not large enough to explain how equal amounts of matter and anti-matter in the early universe could have evolved into the matter dominated universe we have today.
5) Why do the different particles have the masses that they have? Why is the muon 200 times heavier than the electron? What determines that number?
If I had to gamble, I would gamble that any revolutions will be connected to the understanding of mass.
Re:comparable ramifications? (Score:3, Informative)
I would post an addendum to this. "yet....." Genome sequencing is just the beginning of the process of understanding how systems work and how they pathologically fail. As you know, sequencing is simply finding out which genes are which. Finding out what they do and in which combinations is now going to be the hard work that could not be accomplished without the knowledge provided by genome analysis.
Combinatorial analysis is now also becoming possible with an article in last weeks Science talking about colonies of mice being bred for multifactorial gene analysis of complex problems involving multiple genes. Finding out how to resolve problems such as cancer and blindness will require this level of work.
I think the reason folks expect that nothing has come of genome sequencing is 1) lack of public science education 2) unreasonable investor expectation of fast profit.
Re:Er -- Einstein was deeply religious (Score:2, Informative)
Saying Einstein was deeply religious is disingenuous, like saying that Thomas Jefferson was deeply religious. It is true in the sense that he believed in a Creator, but he didn't believe in the kind of activist answer-the-prayers snowy white beard in the clouds Creator that sends gays and women who have abortions to Hell. Evangelist Xtians make the link between these respected thinkers and themselves in order to seem rational. It is a false link; they have just as much in common with these belief systems as they have with fundamentalist Hinduism.
"God doesn't play dice with the Universe" is oft quoted and deeply misunderstood. Check out other quotes by Einstein in order to understand [infidels.org] his position in a non-jingoistic manner.
Copernicus' ideas attacked the religious establishment, not God himself, but the statement is irrelevent to the discussion. I think this thread is about intelligent design, and since Copernicus was never exposed to the ideas of evolution, its a little ridiculous to bring him into it. I doubt he believed in washing his hands after he went to the bathroom. He died in 1543 and modern sanitation was invented in the 20th century.
Christianity obviously didn't lead to the formulation of the scientific method; it existed in ancient Greece. It's debatable whether religion had any role in the development of the scientific method; I would contend that it didn't.
Re:Universes on multiple membranes. (Score:2, Informative)
This is
Different beasts - the model you favour assumes as an axiom that forces act in the extra direction. This would cause very visible effects. _Really_ visible effects - the most obvious of which being the propagation of matter through all available spatial directions unless some magical force acted to confine it.
(magical? That's an argument by belittlement!
I am not read up on the membrane model--I merely stated that, of the models listed among the parent, it was the one that sounded most sensible. I very much may have misunderstood that--which is fine. I misunderstand sects of Bhuddism and Islam too. In any case...
If there is "more reality outside of our universe", we may simply not be noticing effects of it because not enough time has passed since the formation of "our universe." If there is a seperate reality beneath the "aether*" of our reality, we may simply not notice effects because the fabric of space-time isn't "linked" across the barrier, or isn't "linked" enough to cause a detectable difference.
(I use the term "aether" to mean the "fabric of space time." It's neither matter nor energy, but the actual fabric of existance. At the very least, it's a convenient word.)
This is why you are actively supporting a model that makes more assumptions than usual?
Once again: I am not "actively supporting" anything. I'm engaging in a discussion on
As for parsimony--while the simplest answer is the one that should be used until disproven, that doesn't mean that the simplest answer is always right. I put forth that we are incapable of emphiriacly proving any cosmological model, and so in this realm of theorism, parsimony need not be the ruling principle that it is in science.
Re:Publishing hype (Score:3, Informative)
Re:Lee Smolin et al (Score:1, Informative)
Did you read the whole book? He went to lengths attempting to justify why it was a scientifically verifiable model. Specifically, it makes the following prediction: we are at a local maximum for black hole formation, so slightly perturbing any of the fundamental constants will lead to a universe with a smaller rate of black hole production. He made limited attempts to verify this prediction; he was able to justify it for some of the constants, but varying other of the constants had unknown effects on black hole production. There was no clear case of perturbing the constants leading to an increase in black hole production, though, so the model was not ruled out on those grounds.