Please create an account to participate in the Slashdot moderation system


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment Re:What is "real" ? (Score 5, Informative) 80

As real as the neutrino. The neutrino was a prediction based on a model of physics at the time and remained theoretical for thirty years until an experiment confirmed their existence. Like the Higgs, it was thought to be nearly impossible to experimentally verify for a very long time. And when it was observed, it was not observed directly, but through the behavior of particles it interacted with. The interacting particles, in order to behave as they did, must have interacted with something that had the precise qualities ascribed to the neutrino. Therefore, a neutrino must have interacted with them. Therefore, neutrinos exist.

Now we have hot and cold running neutrinos and can use them to probe all sorts of interesting things. But we have still not directly observed them in a detector, because, by their nature, they don't show up. But we know that when we see particles behaving as if they interacted with a near massless, half spin object interacting weakly, we call it a neutrino and move on.

Comment Re:Not Skynet enough (Score 1) 220

In those circumstances, cables, protocols and cable tenders would even work. Imagine you're in the suit, you are restricted to this area around the airframe, your cable is on an automatic spool and you do a set series of movements worked out ahead of time to minimize crossing your own path. Cables may be a pain, but that means your lifting capacity is fully devoted to ordinance and fuel, rather than ordinance, fuel and your batteries.

Comment Re:Not Skynet enough (Score 1) 220

Yep. Plus, the caterpillar loaders can be near external power, meaning the wearer doesn't have to worry about the added weight imposed by the power source. A 2-3 day patrol is going to need some pretty serious power storage and generation. These systems are great for hauling 100 lbs worth of equipment, but how good are they at 100 lbs of equipment plus that in generators and fuel?

Remember, the breakthrough that made Iron Man possible even in the movie was not a breakthrough in robotics, armor or servomotors, but the development of the perfect power source: small, light, massive output and requiring no bulky fuel. Without the arc reactor, Tony's suit was just so much dead weight.

Comment Re:Please explain to this non-physics-type geek (Score 5, Informative) 180

Currently, things weigh more than they should. The mass of a particle is a function of the kinetic energy of the particle and it's component parts, if any. If we run the numbers, we get good masses for some particles, not good masses for others. A proposed solution to this problem is the Higgs field, a nonzero field that permeates space. Anything coupling with this field gains additional mass through interaction with the field.

Picture a person at a party. Normally, they are free to move through the party fairly easily. Now make that person famous. Admirers flock around, and the celebrity has trouble moving. Nonfamous people are particles that do not couple with the HIggs field. Celebrities are particles that do couple with the field, surrounded by a paparazzi of virtual Higgs particles.

Nice theory. It fills a gap in the standard model and now the math all works. So now we have to find the particle. You need the mass of a particle to find it in an accelerator. Roughly (very roughly), you need to create collisions where the sum energy of the little explosion is about that of the particle in question, then watch a statistically large number of those to see if something matching your particle appears. If it does, it's off to Stockholm for dinner with the king. If not, it's back to the drawing boards.

The problem is, the theory doesn't predict the mass of the particle. It doesn't even say if it is one particle, a family of similar particles or a family of different particles. So there's a wide spread of masses to examine. And all the masses are really high, far higher than any other existing accelerator could reach. So we have the new CERN experiment, slowly scanning the possible masses, looking for the particle.

If we don't find that particle, then we're back to square one, why are some particles heavier than predicted? For decades, we've assumed it was some sort of variant of the Higgs boson. But if that's not the case, it's back to the blackboard for more theories.

In general, this is a problem for particle physics. Finding or not finding the particle will affect chemistry, biology and general astronomy not at all. It might or might not have an affect on cosmology, but that's hard to say without a particle to talk about. More interesting for cosmology is that while searching for the Higgs, the experiment might come across more esoteric things, such as evidence for supersymmetry. Evidence for supersymmetry would automatically generate the prime number one candidate for dark matter. And nailing down the properties of dark matter would give us another probe of the Big Bang.

More information than you wanted probably, but I hope it helps.

Comment Re:The Soudan Mine can be toured (Score 1) 158

Yeah, that happens. My present job is helping make lightning detectors. When I applied for the job, I was heartbroken to learn there was not a cage somewhere in the building with a giant tesla coil set up for testing.

I've had a number of disappointments like that. The dye laser I worked with in college looked like a fuel injector hooked to a paint bucket. The pump laser was an anemic old argon ion device that maybe put out 0.75 W on a good day. My senior project carbon 60 experiments used tiny glass ampules that only changed color from orange to darker orange. Even the massive magnet we used to check for superconductivity was only impressive for the sheer amount of iron. All in all, physics labs were disappointing.

Especially compared to those jerks over in Nuclear Engineering, shooting the control rods out of the student reactor and flooding the room with Chernikov radiation and firing up the beta gun to capture lightning bolts in lucite because it was Thursday and there was nothing better to do. And don't get me started on how once they hit grad school, they could climb the walls like spiders or shoot frikkin' laser beams from their eyes.

Comment Re:That's what's wrong with Physics today (Score 3, Insightful) 196

Er, they do realize that Kepler's laws do not apply to galaxies. They cannot, in fact, use Kepler's laws because they know quite well that the gravitational contribution of the stuff orbiting the center of mass is significant. That's why they use Newtonian physics in this situation. Our modern understanding of the evolution of spiral arms comes from this sort of analysis. They do not use Special or General relativity in this situation for two reasons. First is that the math is real hairy. Second, at these speeds and distances, it reduces down to good old Newtonian motion anyway.

As for Dark Matter, yes, there was a flash in the pan article a few years back about someone using General Relativity to analyze rotation curves and coming up with enough extra contribution to invalidate dark matter. The paper was up on ARXIV for about four hours before the first math errors were spotted and brought the whole thing crashing down. And even if that paper held, it wouldn't have explained results like the Bullet Cluster (, where maps of particulate dark matter have been made. No modified gravity theory or assertions that dark matter goes away under SR or GR can explain those findings. Dark matter is real and we now have tools with which we can spot it. The trick is now to figure out what it is.

You seem to have a real misunderstanding of how physics, and all science, makes progress. Once we have theoretical models, they are, generally, perfect. A good theoretical model explains ALL available data, or it isn't a good model. Once we have a good model, the only way to improve it is to go actively looking for where it diverges from reality. Only with this new input, divergence from theoretical predictions, can models be refined, improved or even replaced.

That's why we're hunting the Higgs particle. Fact is, the Standard Model is slightly broken. Without a Higgs mechanism, predicted lepton mass does not conform with experiment. We have a gap right now, a discrepancy. We think we have a solution in the Higgs field. We could, I suppose, assume there's a Higgs field, pick one of the several variants and go with it. Or we could, you know, do some actual science and go looking for the thing and nail down its properties. Along the way, if we see some of the other things we're half expecting, super symmetry, discrepancies in gravity at the millimeter range, broken symmetries, energy leakage at high energies or anything else, so much the better.

The problem with science is not a lack of fundamentals. The problem is the theories are too damned good. Reality simply does not diverge from the theories unless we get into some really exotic conditions. Why do we need a superconducting particle collider with a diameter measured in kilometers? Because our models are frikkin' perfect for everything up to that. We know they're wrong. We know we can't reconcile GR with the Standard Model. But we won't know how to proceed until we can break either GR or the Standard Model. We don't know what piece of the puzzle is missing until we actually go and look at things.

Comment Re:Math? (Score 3, Informative) 153

It's also a difficulty with language. In physics, mass and weight are two separate concepts. We have comparison words for weight: heavier and lighter. But we do not necessarily have the same comparison words for mass. So we're stuck with the English default construct of more massive and less massive. Sure, we could use lighter in this context and hope everyone understands we really are discussing the concept of mass, not gravitational attractive force to the local big rock, but most physicists dislike that imprecision.

Comment Re:'recalling' email - laugh! (Score 1) 384

A MAPI message consists (loosely) of a number of key/value pairs in addition to the standard internet email format. When a MAPI message is sent from one Exchange server to another, these key/value pairs are preserved. When it bounces through any non-Exchange server, this nonstandard information is stripped off (why they didn't hide it in an attachment I don't recall). If a recall fails to operate successfully and there are Exchange servers at both ends, you know the messages are being routed through a non-Exchange server at some point. You should also see problems with meeting requests, notes, contacts or any other nonstandard email type Outlook uses.

Comment Re:'recalling' email - laugh! (Score 5, Informative) 384

Message recall. Oh dear.

Years ago, I wrote the bulk of this feature. It is not an Exchange feature, but an Outlook feature. It works by sending a custom MAPI message that Outlook recognizes and processes. Of course, this only works if all recipients are using Outlook. It also, after we did some usability testing, only deletes unread email, or email that has not been moved to a subfolder (the original version was quite determined and would hunt down and kill the message even if it had been moved to a subfolder, renamed or entered the email protection program). In this way, it did not violate the UI dictum that the computer move things around when you haven't given it instructions to do so.

So yes, it is Outlook only. If sent to a non-Microsoft mail system, it degrades to a simple notification that the message is being recalled. And it does not a good choice for getting rid of flames you shouldn't have been sending. But within its expected use as a feature - correcting mistakes in email that should have been caught before pressing send, it works fairly well.

But because it is client based, rather than an Exchange feature, it does cause a new mail message to be sent to each original recipient and, combined with a send-all storm, could greatly exacerbate things.

And, preemptively, for those who have philosophical objections to me having written the code in the first place, I'll just have to live with your disapproval and hope my steady paycheck somehow sooths my guilty conscience.

Slashdot Top Deals

When in doubt, mumble; when in trouble, delegate; when in charge, ponder. -- James H. Boren