Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: Re:It's a Small Universe (Score 1) 429

by Fuseboy (#48336361) Attached to: Mathematical Proof That the Universe Could Come From Nothing

You could be right - I mean, I'm familiar with the idea that 'time' disappears as you get to the very, very early universe. Even so, the paper's abstract is using causal language: "the universe could be spontaneously created from nothing" - "once a small true vacuum bubble is created by quantum fluctuations"

This may be sloppy language, but it seems to imply there's just the metastable false vacuum, then - paf - there's an expanding universe. If the metastable false vacuum has no time, what does it mean for it to fluctuate? Is it a sort of static, superimposition of states (but without a timelike relationship between them) and a very small number of those states are associated with the low-entropy end of a universe? I have no idea.

Comment: Re:Much Confusion (Score 1) 247

by Fuseboy (#47766227) Attached to: Fermilab Begins Testing Holographic Universe Theory

Yes, I suppose it does mean that the 'computer' running the universe might be a black hole.

I'm not sure what we can say about the nature of that black hole. I doubt very much that its spin, for example, would impart motion to galaxies, any more than rotating your computer would do anything to your Minecraft game. It's not a fish tank or a snow globe, it's a computer.

Similarly, remember that the 'inner' and 'outer' black holes don't even exist in the same universe, if indeed our universe is the result of a calcuation. The inner and outer black holes will never meet, any more than switching off dark energy in your (physically realistic) Minecraft game would cause your Minecraft universe to somehow touch your computer.

Comment: Much Confusion (Score 5, Informative) 247

by Fuseboy (#47764953) Attached to: Fermilab Begins Testing Holographic Universe Theory

There's a lot of confusion about what this means, but to be clear: this has nothing to do with ghostly 3D things floating in a surrounding room.

What it's saying is that the 3D nature of the universe might be only approximate. Let's say you (somehow) come up with a two-dimensional universe and physical laws, in which you can mostly accurately (but not completely) calculate the ongoing evolution of a 3D universe. The "mostly accurately" part translates into a slight blurriness, a fuzziness of the 3D world, but it occurs at such small scales that nobody will notice.

Such models have been created theoretically - not long ago some bright spark concocted a ten-dimensional universe that had relativity and spatial deformations and whatnot, but which was mathematically equivalent to a one-dimensional universe that did not.

This experiment is looking for the blurriness.

Now, the story of how this got started is fascinating. Some other bright spark was investigating entropy (chaos), and in particular was interested in the maximum amount of chaos that could be contained in a three-dimensional volume. In a sense, this is like asking the maximum information density of a volume.

Somewhat bizarrely, the equation for the maximum entropy is proportional to the surface area of the volume. This is really weird, and important. The maximum amount of information you can cram into a space is limited by the space's surface area, not its volume.

The implication of this is that you could characterize the entire state of a 3D volume with a membrane. This has been proposed as one solution to the black hole information paradox - black holes are a place of no return, and so they seem to violate the law that information (like energy) can't be created or destroyed. The solution is this: as particles enter the black hole, you get tiny peturbations (bulges, dimples, ripples) in the black hole's event horizon. The idea is that the entire state of that particle retained in these peturbations as they play across the event horizon. The information isn't lost, it's just encoded in this 2D form.

This leads to the startling idea that the peturbations as they evolve are actually modelling the ongoing state of the interior of the black hole. Modelling.. calculating.. simulating. The peturbations on the event horizon are a 2D calculation of the state of a 3D volume.

This is the holographic theory - what if our entire universe, despite its apparent 3D nature, were in fact equivalent to a 2D simulation.

Comment: Lack of Competition (Score 1) 278

by Fuseboy (#47656407) Attached to: Ask Slashdot: Why Are Online Job Applications So Badly Designed?

Simple - there's a lack of competition. It's the same reason renewing your driver's license or passport or whatever sucks, they're the sole vendor, so there's little incentive for them to make it easy or convenient.

Also, it cuts down on spam. If it's hard to apply, then only the most enthusiastic applications will do it - or so one line of thinking goes. (That can backfire; talented and in-demand applicants might not find it worth their time to bother.)

Comment: What this means (Score 5, Informative) 433

by Fuseboy (#45663889) Attached to: Simulations Back Up Theory That Universe Is a Hologram

Someone clever was working out the maximum entropy of a black hole, and found that (unexpectedly) it was proportional to the surface area of the event horizon, not its volume. After some more thought, other clever people found that the full state of every particle that falls into a black hole remains encoded as oscillations and deformations of its surface area.

This leads to the realization that the despite the fact that a black hole's event horizon is seemingly much simpler than a full-dimensional portion of a universe, it's theoretically possible that it's just as rich a simulation. Perhaps the "real" representation of the universe is actually just a rippling membrane, and the 3D view we see around us is just an alternate interpretation. This is where the word "hologram" comes in - it's only an analogy (because flattish holograms seem to encode 3D data).

Now, the word "real" is misleading - neither representation is 'more true', it's just that the fewer-dimensional representation might be a lot simpler. A comparable situation is the way the earth goes around the sun, or the sun goes around the earth. A stationary sun makes models of the planetary orbits a heck of a lot simpler, but a stationary earth makes it a lot easier to give directions to your party.

All of this was theoretical until this recent finding. The researches created two mathematical models of the universe - one of them ten-dimensional (similar to some forms of modern theories of our universe, though the article points out their model was simpler). The other model was a one-dimensional universe filled with ideal springs. These models were identical, in the same way as the 3D universe and the event horizon - they're alternate ways of calculating the same thing.

The researchers discovered that simulations in both of these universe models have the same output - in other words, they do seem to be different ways of describing the same universe.

Comment: Culture of Paranoia (Score 1) 114

by Fuseboy (#35443972) Attached to: Book Review: Social Engineering: The Art of Human Hacking

It will be interesting to see what effect this has on customer service generally. Is it possible to have sensible, non-theatrical security procedures that are preliminary and don't interfere with an essentially friendly relationship? Or will the attitude of security consciousness turn into a strange form of paranoid bureaucracy that colors everything?

Comment: Core Competency (Score 2) 30

by Fuseboy (#34985528) Attached to: Computer Incident Response and Product Security

This shouldn't be surprising - an organization's purpose is to do what it does, to quote somebody or other. TJX is making money off transactions; security is only incidental, and responding to unusual events runs counter to the grain of an optimized organization. The 911 call center, on the other hand, is helping people as a matter of course. (Just see how well they do when they start trying to make money off the transactions! j/k)

Comment: Re:Dark matter vs black holes (Score 2) 174

by Fuseboy (#34907682) Attached to: Milky Way May Have Dark Matter Satellite Galaxies

That doesn't sound quite right - because of the inverse-squared falloff of gravity, once you're a certain distance away, black holes and stars aren't much different in how material orbits around them.

One difference is that that black holes often spew high-energy x-rays as infalling matter is crushed, whereas dark matter is - well - dark.

Comment: Re:OH COME ON (Score 1) 171

by Fuseboy (#33715342) Attached to: Methane Survey Reveals Mars Is Far From 'Dead'

Sometimes I think this whole notion of extraordinary has more to do with our imagination and cultural background than anything scientific. I mean, wouldn't it be absolutely mind-boggling if we kept encountering massive energy-rich zones (e.g. geologically/chemically active planets) that were completely devoid of microbial life? If/when we find life elsewhere, of course it's going to be extremely significant, but does that make it unlikely?

Comment: You can't handle the truth (Score 2, Interesting) 539

by Fuseboy (#33451896) Attached to: Facebook Post Juror Gets Fined, Removed, Assigned Homework

Given recent articles about snap decisions (apparently deciding if you think a gal's hot, or your emotional reaction to a web site both take a fraction of a second), perhaps all this woman was doing was revealing an uncomfortable truth about the justice system. Could it be that jurors reach their decision in the first few minutes (or less) and everything that follows just loads them up with ammunition to form their rationalizations?

"One Architecture, One OS" also translates as "One Egg, One Basket".