Search found 33 matches

by The_Spectre
Sat Nov 22, 2008 8:39 pm UTC
Forum: Science
Topic: Zapping paint with magnetism
Replies: 4
Views: 1097

Re: Zapping paint with magnetism

Most metals are in fact not ferromagnetic, iron is one of the few exceptions in that regard. Cobalt and Nickel from your list are, though. However, in your case, I think the relevant metallic property is conductance, as you seem to want to apply a varying magnetic field which would induce a current ...
by The_Spectre
Sun Oct 26, 2008 12:53 pm UTC
Forum: Science
Topic: Electric motor experiment
Replies: 1
Views: 781

Re: Electric motor experiment

Even if you end up making a more complicated one, bring the materials for this one as well:
http://www.evilmadscientist.com/article ... polarMotor

Or this one, which is more finicky to make but prettier once it's working:
http://dangerouslyfun.com/homopolar-motor
by The_Spectre
Mon Jul 07, 2008 3:54 pm UTC
Forum: Science
Topic: What do you think we will see at the LHC?
Replies: 160
Views: 20548

Re: Question about the Large Hadron Collider

There's an upper limit to the mass of the Higgs boson, assuming it works the way we think it should (and if it doesn't, it's not really the Higgs boson but something else). This upper limit is calculated from the assumption that the Standard Model is the correct model for electroweak interactions (a...
by The_Spectre
Sat Apr 12, 2008 2:39 am UTC
Forum: Science
Topic: Silly question about heat in a vacuum
Replies: 6
Views: 1306

Re: Silly question about heat in a vacuum

I think it would dissociate into gaseous hydrogen and solid carbon (eventually gaseous carbon) and such, even without oxygen present to make H2O and CO2.

Disclaimer: This might be nonsense.
by The_Spectre
Fri Feb 15, 2008 7:05 pm UTC
Forum: Mathematics
Topic: "Oh no! We forgot how to say... math... stuff!"
Replies: 294
Views: 92262

Re: "Oh no! We forgot how to say... math... stuff!"

Pi would be 6.283... . A full circle of radians. ei Pi= 1, and all sorts of wonderful things.

http://www.math.utah.edu/~palais/pi.pdf
by The_Spectre
Mon Dec 17, 2007 8:45 am UTC
Forum: Science
Topic: local sidereal time/vegas
Replies: 2
Views: 1680

Re: local sidereal time/vegas

This isn't really science, although I guess there isn't a "silly pseudoscience" subforum here...
by The_Spectre
Wed Oct 31, 2007 10:23 am UTC
Forum: Mathematics
Topic: Proficiency with LaTeX
Replies: 86
Views: 14163

Re: Proficiency with LaTeX

Does anyone here know how I can put an arbitrary mathematical expression directly under another? For example, a subscript applied to \lim or \sum appears directly under the limit or summation sign (in display style), but a subscript applied to, say, \mathrm{Prob} does not. I know there's a way to d...
by The_Spectre
Wed Oct 31, 2007 12:10 am UTC
Forum: Science
Topic: Is there justification for waves
Replies: 29
Views: 2884

Re: Is there justification for waves

Why do we use quantum mechanics? Because it works. Why does stuff behave in a quantum way in our universe? Because if it didn't, and everything was classical, atoms wouldn't be stable (and various other major problems). So if some bearded guy (or string theory or whatever) creates some universes, so...
by The_Spectre
Thu Oct 18, 2007 8:48 am UTC
Forum: Mathematics
Topic: Population growth in mythical Mesopotamia
Replies: 5
Views: 1495

Re: Population growth in mythical Mesopotamia

Your math looks fine to me. Why are you surprised that the math in some ancient myth sucks? Some assumptions that are radically different from yours but also not unreasonable give something completely different, though: 1. Every couple produces 4 kids. 2. This takes them about 30 years. (They live f...
by The_Spectre
Fri Oct 12, 2007 10:04 am UTC
Forum: Science
Topic: Relativity Problem
Replies: 5
Views: 1226

Re: Relativity Problem

Tchebu wrote:Amirite?

No. Robin S was. The world works with general relativity, not special. In high school, they obviously won't have gone through the real formalism of GR, but the teacher could quite possibly have made a vague statement about time slowing down in a gravitational field.
by The_Spectre
Fri Oct 12, 2007 9:28 am UTC
Forum: Science
Topic: Portal Physics
Replies: 75
Views: 9715

Re: Portal Physics

The latest Penny Arcade has the answer to this one.
by The_Spectre
Tue Oct 02, 2007 9:49 pm UTC
Forum: Mathematics
Topic: Need some help with this equation!
Replies: 29
Views: 2813

Re: Need some help with this equation!

It's sufficiently complicated that there is no exact solution in terms of standard functions. You folks talking about cubics and quartics in Z^1/2 seem to be mistaken, it's not a nice polynomial in Z^1/2 at all. So, use a numerical method. A modern graphing calculator or math software will do the tr...
by The_Spectre
Wed Sep 26, 2007 7:19 pm UTC
Forum: Mathematics
Topic: Complex Roots
Replies: 5
Views: 1293

(e^a) *(cosb + isinb) = 1

You're almost done. Take real and imaginary parts on both sides, this gives you two equations from which you can easily find a and b.
by The_Spectre
Fri Sep 14, 2007 12:35 pm UTC
Forum: Language/Linguistics
Topic: Names of Nations
Replies: 101
Views: 13535

Re: Names of Nations

But why? The official name for the country is Bundesrepublik Deutschland . English speakers are certainly capable of calling the country by it's proper name, or at least a closely related anglicized version. Dutchland , perhaps. Using "Dutchland" in a serious way is a pretty bad idea. You...
by The_Spectre
Fri Sep 14, 2007 10:58 am UTC
Forum: Science
Topic: Physics: Faster Than Light?
Replies: 3
Views: 1784

It all depends on your frame of reference. I think an example would illustrate best. Say there's a star 10 light-years away as measured by observers on earth, and not moving with respect to earth. Some crazy astronaut travels from earth to that star at a speed very close to the speed of light (Actua...
by The_Spectre
Mon Sep 10, 2007 8:16 pm UTC
Forum: Science
Topic: Conservation of Energy
Replies: 20
Views: 3869

I think the op3raman should get a cookie. You know, for looking at it the best way. I'm pretty sure he is correct. I think John Baez is more deserving of this particular cookie (link in my first post in this thread). He's right, while operaman is in fact wrong. http://en.wikipedia.org/wiki/Redshift...
by The_Spectre
Sun Sep 09, 2007 9:46 am UTC
Forum: Science
Topic: Cracking Bottles
Replies: 4
Views: 2623

by The_Spectre
Sat Sep 08, 2007 4:04 pm UTC
Forum: News & Articles
Topic: Radiation absorbing mineral found
Replies: 8
Views: 3787

The article seems to use the words "radiation", "radioactivity" and "radioactive substances" interchangeably. They probably mean "radioactive substances" each time. When you consider that the scientists probably meant certain specific radioactive substances an...
by The_Spectre
Thu Sep 06, 2007 7:48 am UTC
Forum: Science
Topic: Damaging materials - why not use ionizing radiation?
Replies: 22
Views: 2222

http://en.wikipedia.org/wiki/Neutron_bomb

The reason the neutron bomb is the only example is that it's pretty hard to make decent amounts of ionizing radiation in any other way.
by The_Spectre
Thu Aug 30, 2007 10:22 pm UTC
Forum: Serious Business
Topic: I'm not concious
Replies: 50
Views: 6449

Re: I'm not concious

zenten wrote:Lets suppose you come across someone who claims to be neither conscious nor sentient. Would you believe them, and if not, why not?

(emph mine)

Something that is neither conscious nor sentient does not qualify as a "someone" to me. So I disbelieve due to a technicality. :P
by The_Spectre
Fri Aug 10, 2007 6:46 am UTC
Forum: Science
Topic: Levitation!
Replies: 12
Views: 2748

Anyone talking about geckos in this context is confusing the Casimir effect with the van der Waals force. The press release of the university itself does it too, though, so I don't know what's going on there. Pretty silly.

http://www.st-andrews.ac.uk/news/Title,14834,en.html
by The_Spectre
Wed Jul 25, 2007 10:18 pm UTC
Forum: Science
Topic: Conservation of Energy
Replies: 20
Views: 3869

Lots of confusion in this thread. Cosmological redshift, the redshift (reduction in energy) of photons due to the expansion of space, does happen. Does this violate conservation of energy? Yep. Is this a problem? Nope. Conservation of energy is pretty iffy when General Relativity is involved. This i...
by The_Spectre
Sat Jul 21, 2007 12:13 pm UTC
Forum: Mathematics
Topic: Poker odds question.
Replies: 11
Views: 3474

Number of distinct table card possibilities: Ntot = 50 choose 5 Number of table card possibilities with 3 cards of the right suit (and 2 of wrong suits): N(3) = (11 choose 3)*(39 choose 2) Number of table card possibilities with 4 cards of the right suit (and 1 of a wrong suit): N(4) = (11 choose 4)...
by The_Spectre
Mon Jul 02, 2007 12:15 am UTC
Forum: Science
Topic: electromagnetic conundrum
Replies: 18
Views: 3487

The magnetic force between two particles with the same charge moving parallel to each other would actually be repulsive. You can use whatever right-hand/corkscrew/pistol rule variant you learned to figure this out. Are you sure? Using the relevant right hand rules, I find the magnetic fields should...
by The_Spectre
Sun Jul 01, 2007 10:02 pm UTC
Forum: Science
Topic: electromagnetic conundrum
Replies: 18
Views: 3487

Well, the force a magnetic field exerts on a moving charge is given by the Lorenz force law, F = q(VxB). (The symbols, in order: Force, charge, velocity, cross product, magnetic field). We were always taught that the v was the velocity of the charge *with respect to* the magnetic field. So, for exa...
by The_Spectre
Sun Jul 01, 2007 9:53 pm UTC
Forum: Science
Topic: electromagnetic conundrum
Replies: 18
Views: 3487

The magnetic force between two particles with the same charge moving parallel to each other would actually be repulsive. You can use whatever right-hand/corkscrew/pistol rule variant you learned to figure this out. And this does matter. It's actually the important thing to realize to resolve this pa...
by The_Spectre
Wed Jun 27, 2007 1:12 am UTC
Forum: Science
Topic: relativity & standard model question
Replies: 7
Views: 2689

Well, my fist answer would be: the Higgs gives them mass, but only mass without any gravitation ... Gravitation is something completly different and has nothing to do with the higgs .... Yep, this is completely correct. The Standard Model does not include gravity in any way. Reconciling the standar...
by The_Spectre
Thu Jun 07, 2007 2:29 pm UTC
Forum: Mathematics
Topic: Geometry Problem
Replies: 5
Views: 2571

Working in centimeters, call x the distance from the center of the square to any of its four corners. Then the radius of the circle is 16 + x. Draw the radius that goes from the center to the point where a blue line touches the circle. This is the hypotenuse of a right triangle whose leg lengths ar...
by The_Spectre
Sat Jun 02, 2007 1:35 am UTC
Forum: Mathematics
Topic: A debate over some simple probabilities
Replies: 48
Views: 9054

I'll tell you a shocking story. This morning, I parked my bike next to a car that had the following license plate number:

JF-24-UE

Amazing, isn't it? I mean, the odds of that exact license plate number are really really tiny!
by The_Spectre
Fri May 18, 2007 1:33 am UTC
Forum: Science
Topic: Reputable Source? The Electric Universe
Replies: 2
Views: 2760

I googled it.

http://www.holoscience.com/

It's a crackpot site.
by The_Spectre
Fri May 18, 2007 12:09 am UTC
Forum: Science
Topic: Lightning bolts - check equation please...
Replies: 11
Views: 5490

I was pleased to find out that google calculator knows that mass and energy are the same thing, and will happily convert between the two.

http://www.google.com/search?q=500+megajoules+in+grams

So yeah, your answer is a factor of 10 too high somehow.
by The_Spectre
Sun Dec 03, 2006 3:05 pm UTC
Forum: Logic Puzzles
Topic: Temperatures
Replies: 60
Views: 13403

Physicist here, just to shake things up:

In thermodynamics, we do sometimes deal with negative temperatures. The weird thing is that they're actually "hotter" than positive temperatures, including positive infinity.

http://en.wikipedia.org/wiki/Negative_temperature
by The_Spectre
Sun Dec 03, 2006 2:37 pm UTC
Forum: Logic Puzzles
Topic: 3 Spiders and a Fly [solution thread]
Replies: 15
Views: 6464

The solution Erasmus posted doesn't work, as was said by some people. I think I have one: I'm going to shamelessly abuse this image of a tetrahedron with the vertices labeled, I found it with google images: http://classes.engr.oregonstate.edu/engr/winter2003/engr321/HW2.ht10.gif Let one of the spide...

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