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Evidence of 6 Dimensions or More?
shelflife writes "Nature.com is reporting that there may be evidence of 6 dimensions. Galaxies seem to behave as there were more matter in them than is actually visible. 'One explanation, they say, is that three extra dimensions, in addition to the three spatial ones to which we are accustomed, are altering the effects of gravity over very short distances of about a nanometre.'" Update by J : Like most of string theory, this is acknowledged by its authors to be "extremely speculative."
That in at least one of the six that hopefully the geeks get the girls :P
"GET / HTTP/1.0" 200 51230 "-" "Mozilla/4.0 (compatible; Setec Astronomy)"
This is clearly false and evil. The Time Cube has exactly 4 dimensions.
An open mind is a slop bucket, "THINK CUBIC".
Please alter my pants as fashion dictates.
But then again, if they do manage to actually find solid evidence (not just its apparent invisibility in our traditional 3 or 4 dimensions) of matter in an unexpected dimension, I will be extremely impressed. It's an interesting theory at any rate, and worth looking into.
The way I understood this phenomenon, as it was explained in Kaku's book, was that the extra dimensions were curled up on themselves so that they were smaller than could be detected.
The thought experiment was similar to the following. Imagine a sheet of paper with a line crossing from one edge to the opposite edge. You can see that the line exists when viewing the sheet in two dimensions. However, imagine if you rolled the sheet of paper up tightly with the line not directly aligned with the roll. Now you would have instead of a line a single dot or a series of evenly-spaced dots. The line hasn't gone anywhere, it has simply been rolled onto itself so that it seems to have become small and barely detectable.
Now extend that idea to multiple spatial dimensions beyond just two or three. Since we humans can only perceive three spatial dimensions, it is hard to imagine what multiple extra dimensions would be like. However, if we can take the extra dimensions and "roll" them into themselves, we can make a little more sense of the concept.
Jesus saved me from my past. He can save you as well.
It's simple: They plug what they observe into a mathematical model and see if they can come up with a model that matches observation. It's not simple blind guesswork.
Someone came up with a model called string theory that includes systems with multiple "hidden" dimensions.
The dark matter they're talking about in the article is behaving in a way predicted by one of the current string theory models, which doesn't fit the more traditional models, thus the assertion that it must be 6 dimensions at work.
Alert: The fourth, fifth, and sixth dimensions were slashdotted today due to uncontrollable inflow of nerds, geeks, and other creatures.
To keep the traffic flow normal, mirrors have been provided on the seventh, eighth, and ninth dimensions for the earthlings...
This is why the theory of relativity is a joke. Whenever they run into a problem, they throw in more gammas or some other kludge, like gravitation being the same as acceleration.
This is why Newtonian physics is a joke. Whenever they run into a problem, they throw in more integrals or some other kludge, like momentum being preserved.
This is why bakery is a joke. Whenever they run into a problem, they throw in more meal or some other kludge, like lowering the temperatur of the oven.
"Stop failing the Turing test!" -- Dilbert
Greene's Elegant Universe
The Mechanical Universe
Last book I enjoyed, Three Roads to Quantum Gravity by L. Smolin... ya, ya, I know, nothing fits, is, isn't, yo momma... no yo momma... can, can't... I'm not touching you!
"Academicians are more likely to share each other's toothbrush than each other's nomenclature."
Cohen
superstring theory and yang-mills theory deal with 11-D subspaces and their intersection with 2D string worldsheets (think a 1 dimensional string flying through the air, but extended along the temporal dimension, forming a 2 dimensional sheet).
This has been worked on for a while, and the equations are getting there. If you think about it though, a fifth dimension can be easily produced from the equations of general relativity, and maxwells equations of electro-mag produce yet another micro-dimension to govern the electromagnetic force.
So this isn't that surprising, the problem is the math for 11 dimensions doesn't work well yet, because it's freaking hard to do energy waveform equations in 11 dimensions, when you don't even know how those 11 dimensions are laid out.
The next breakthrough in physics will be a model for at least some of the underlying dimensional geometry, leading to a final m-theory, likely the long sought theory of everything.
I just like the fact that the standard model is showing it's flaws, trying to write theory to fit your experiments is never as good as trying to understand the underlying causes and drawing conclusions from the emergent properties of the basic model.
The first rule of USENET is you do not talk about USENET.
is this in anyway related to the string theory?
The only problem is that when the calculation is done, the universe's dimensionality is not four as one may expect (three axes of space and one of time), but twenty-six. More precisely, bosonic string theories are 26-dimensional, while superstring and M-theories turn out to involve 10 or 11 dimensions.
HD Trailers
Observational Evidence for Extra Dimensions from Dark Matter
(It's actually a draft of a paper submitted to Physical Review Letters, not yet approved.)
It's a nice phenomenology paper without any heavy math that puts together a bunch of theoretical ideas floating around. Even better, it has testable hypotheses! (unlike many papers these days)
- Gravity should deviate from the inverse-square law at the nanometer scale.
- Dark matter should be composed of a particle with mass 3e-16 GeV/c^2. (For comparison, mass of electron is 5e-4 GeV/c^2.)
- The large extra dimensions assumptions all this is based on would require us to see all sorts of quantum gravity interactions at the LHC.
Now short-range gravity experiments are just approaching the micron scale, so we're 3 orders of magnitude away from testing hypothesis #1. I doubt anyone has an idea how to close that gap right now.Checking hypothesis #2 would require some independent way of determining the mass of dark matter particles. I don't know what the sensitivity range of the various dark matter experiments running or planned are. Maybe they would be able to see something this light.
#3 however is going to start running in 2 years, and then we'll get some good information either way.
I agree, that's how it is done. Lots of times that produces pretty good results, sometimes less than stellar.
One of the things they had us do in college, and it is interesting IMO, is to take a sport you know nothing about and observe it. Try to formulate the rules of game based on observation (that is, create the model). Then look the actual rules up and compare them.
It's not a perfect experiment - there are things common amongst nearly all games that we simply just know, but it was interesting how correct you would normally get some things and how wrong others (this is even more true because we *do* have correct preconcieved notions, it gets worse when going blind into something). It's also interesting how you can be correct and wrong at the same time - accuratly predict the outcome but for totally incorrect reasons. And, in some sense, it raises the question of if it really matters if the path to get to the correct point is wrong. If you are correct 100% of the time that it is "pass interference" (in American Football) does it matter that you definition of "pass interference" is wrong?
In really really complicated scenarios I always wonder which side is thier model on (though, of course, it's a sliding scale not just an absolute two sides). Especially given the magnitude that some of the models will evnetually have in our lifes.
Of course, this is what makes these fields so interesting to me, the combination of "right or wrong" with the amount of "feel" and "intuition" in the system.
------- Sorry about the spelling, I suffer from two problems. Dyslexia makes it difficult to spell well, lazy makes it
I'm starting to think that Occam's razor is abused more often than it is used correctly.
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Parent asserted;
Occam's Razor, which is a basic tenent of modern scientific thought says that the simplest explanation is the best.
This is an abuse of the version of Occham's Razor used in modern scientific thought, though an oft repeated misinterpretation.
A better way of phrasing the desire for elegance in modern science is; "Given two identically predictive models, choose the one which requires the fewest assumptions." Reducing the number of assumptions is not always the same as 'simplifying' the problem.
Also, remember that the purpose of science is to generate predictive value. If one of those models is more complex but also more predictive, then it is ALWAYS the better model, no matter how complex.
The original version of Occam's Razor, as correctly expressed in the Wiki article, is "Entities should not be multiplied beyond necessity" where 'necessity' equates to generating the maximum level of predictive value.
Check out the following link, which gives a better summation of the role of Occham's razor in science than the wiki article does.
http://www.physics.adelaide.edu.au/~dkoks/Faq/Gen
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It's the end of my comment as I know it and I feel fine.
Quoting from the wikipedia link you provided:
- "When multiple explanations are available for a phenomenon, the simplest version is preferred"
Occam's Razor is a tool to, when faced with multiple explanations for the same situation, help one choose the best one.
It is not some sort of philosophical statement on how there should be a simple explanation for everything.
Although i too feel unconfortable with the increasing complexity of scientificy theories (and judging from the current moderation on your post i suspect many others also yearn for simplicity), i cannot stand by and see you missuse Occam's Razor (one of the first things i learned in philosophy).
PS: At the risk of spoiling this post, i have to state a theory of mine: I suspect one of the things that turns some scientific minds to the belief on a "higher power" (aka almighty) is a yearning for simplicity and/or an inability/unwillingness to accept complex explanations to the mind-bogling complexity of the world.