Search found 555 matches

by Herman
Fri Feb 27, 2009 5:09 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0549: "Westley's a Dick"
Replies: 126
Views: 32718

Re: "Westley's a Dick" discussion

Crazy Randall. Imagine if we applied morality to heroes!
by Herman
Mon Feb 16, 2009 5:17 pm UTC
Forum: Science
Topic: Velocity including a drag term?
Replies: 5
Views: 720

Re: Velocity including a drag term?

No, no, this is a differential equation, you can't just integrate both sides. And the chain rule doesn't work for integration (at least not directly)! OP, have you taken a DE class? If so, then you know how to solve a first-order seperable equation like this one. (It's first-order in terms of v, not...
by Herman
Wed Feb 11, 2009 5:35 am UTC
Forum: Science
Topic: Why Pluto shouldn't/should be a planet
Replies: 67
Views: 9772

Re: Why Pluto shouldn't/should be a planet

Hell, if you get down to it, Earth shouldn't even be a planet. Any taxonomy that puts Jupiter and Earth in the same category has serious problems. If Jupiter is a planet, then the solar system has four planets and assorted minor planets. science isn't there to prop up nationalism. Nor, um, Earth-ism...
by Herman
Wed Feb 11, 2009 4:25 am UTC
Forum: Science
Topic: stupid question about stars
Replies: 32
Views: 1961

Re: stupid question about stars

Go read Wikipedia for more detail, but, basically, no. White dwarfs and neutron stars are made of very different material than any found in the solar system. A white dwarf forms when certain kinds of stars (including, eventually, the sun) run out of nuclear fuel. The cessation of fusion, and the hea...
by Herman
Fri Jan 30, 2009 6:23 am UTC
Forum: Science
Topic: A little game for evil science types:
Replies: 50
Views: 4455

Re: A little game for evil science types:

If you killed one person per second for about 70 years, and there was no reproduction, that would be around the Earth's population. So yeah, you could just about do it in one lifetime, with a lot of replacement blades, and a LOT of 5-hour energy. Of course, you couldn't run around bashing in everyon...
by Herman
Thu Jan 29, 2009 12:15 am UTC
Forum: Mathematics
Topic: Manipulating the Minimal Surface Equation
Replies: 2
Views: 536

Re: Manipulating the Minimal Surface Equation

Oh, okay. Thanks, I'll play with it some more.

Edit: Got the first part. Any hints on how to solve that ODE? I haven't been able to crack it.

Edit2: Oh man, of course. Okay, never mind.
by Herman
Wed Jan 28, 2009 2:42 am UTC
Forum: Mathematics
Topic: Manipulating the Minimal Surface Equation
Replies: 2
Views: 536

Manipulating the Minimal Surface Equation

This is homework, so hints are appreciated. The class is an undergraduate intro to PDE's, so I'm guessing I don't need anything too advanced. Okay, so the problem says, Let u(x, y) be a solution of the Minimal Surface Equation. Also, u(x, y) = h(r), where r = sqrt(x 2 + y 2 ), as usual. Show that h(...
by Herman
Thu Jan 22, 2009 4:37 am UTC
Forum: Science
Topic: Protecting Earth from the evil Aliens
Replies: 50
Views: 3506

Re: Protecting Earth from the evil Aliens

My special relativity is lousy, but these guys came up with a simple way to use instantaneous communication to transmit messages to your own past. In principle, this could work for finitely fast FTL travel, and for matter, not just information. So yeah, you can use FTL for bona fide time travel.
by Herman
Wed Jan 21, 2009 2:21 am UTC
Forum: Science
Topic: Protecting Earth from the evil Aliens
Replies: 50
Views: 3506

Re: Protecting Earth from the evil Aliens

Assuming that there is some form of FTL travel Use FTL to go back in time. Sterilize planets that will one day spawn invaders. Or you could just use time travel to break conservation of energy, giving you unlimited power for weapons. Or create an AI that could think infinitely fast and come up with...
by Herman
Mon Jan 19, 2009 3:07 am UTC
Forum: Science
Topic: Find Your Personal Lightcone
Replies: 15
Views: 1803

Re: Find Your Personal Lightcone

Previously, Tau Ceti (back when I was 12... I wish I'd known then!)


Hey! My lightcone hit Tau Ceti when I was 12! Wild.
by Herman
Tue Jan 13, 2009 3:34 am UTC
Forum: Serious Business
Topic: Transexuality
Replies: 318
Views: 31972

Re: Transexuality

A "comprehensive theory of psychological gender as it occurs in everyone" is still going to be constructed by researchers who are looking through a partucular lens; between the bias of the existing framework and the apparent relative rarity of trans people, trans people are still likely t...
by Herman
Sun Jan 11, 2009 12:35 am UTC
Forum: Science
Topic: The fastest you can go.
Replies: 24
Views: 2197

Re: The fastest you can go.

Klotz wrote:If a glass spaceship is going fast, to an outside observer the people inside the ship are moving in slow motion.


Interestingly, vice versa. To people on the spaceship, the observers will also appear to be moving in slow motion.

Relativity is weird.
by Herman
Sat Jan 10, 2009 7:19 pm UTC
Forum: Serious Business
Topic: Transexuality
Replies: 318
Views: 31972

Re: Transexuality

Oh, the idea that happiness is contingent upon changing one's physical sex will almost always come from the trans person (although some people who identifiy as trans might not feel that any/all medical aspects of transition are essential in their case). I'm talking about the assertion that the tran...
by Herman
Fri Jan 09, 2009 10:10 pm UTC
Forum: Serious Business
Topic: Transexuality
Replies: 318
Views: 31972

Re: Transexuality

If I can put words in T-Form's mouth for a second, I think the idea of [POSESSIVE PRONOUN] argument is that psycological modification of a person is fundamentally not the same thing as physical modification, because the former changes the actual person, whereas the latter changes just the body. So i...
by Herman
Fri Jan 09, 2009 2:30 am UTC
Forum: Science
Topic: The fastest you can go.
Replies: 24
Views: 2197

Re: The fastest you can go.

So it turns out my physics teacher was wrong. Nevermind. While that's certainly possible, I would like to put forward the countersuggestion, which is that you simply misunderstood your physics teacher... For the sake of the rest of the class, I hope so... Interesting piece of trivia from relativity...
by Herman
Tue Jan 06, 2009 12:23 am UTC
Forum: Serious Business
Topic: Transexuality
Replies: 318
Views: 31972

Re: Transexuality

With regards to the "Magic Pill" discussion, isn't transexuality self-evidently a disorder, in a way that homosexuality isn't? It's characterized by a conviction that one's mental and physical genders don't match; an inescapable feeling of wrongness is built into the definition. Since ther...
by Herman
Thu Jan 01, 2009 12:08 am UTC
Forum: Science
Topic: Neutron laser!
Replies: 30
Views: 10134

Re: Neutron laser!

An idea for application in space battles: Neutrons have a mean lifetime of around 13 minutes, and decay to a proton, electron, and neutrino. Assuming you could fire neutrons at highly relativistic speeds, and had very fine speed control, you could fire a pulse of neutrons at a distant target, settin...
by Herman
Mon Dec 22, 2008 1:39 am UTC
Forum: Science
Topic: Explain to me why this wouldn't work
Replies: 17
Views: 2244

Re: Explain to me why this wouldn't work

If your photocells are just as hot. Won't they emit radiation like that of the metal too?


This. As someone noted above, photovoltaic cells are limited by the Carnot efficiency, because of course when they're heated they radiate like any other object.
by Herman
Mon Dec 22, 2008 1:34 am UTC
Forum: Science
Topic: It's that time of year
Replies: 0
Views: 589

It's that time of year

That's right, it's Santa physics!

I remember one year the last day before winter break, my physics teacher brought in some version of this and read it out loud. Good times.
by Herman
Fri Dec 19, 2008 8:17 pm UTC
Forum: Books
Topic: Should I get into Orson Scott Card?
Replies: 110
Views: 15499

Re: Should I get into Orson Scott Card?

Yeah, see how you like him. My recommendations: Ender's Game Ender's Shadow Speaker for the Dead Enchanted Pastwatch: The Redemption of Christopher Columbus Instead of reading the rest of the Ender series, read Pastwatch again. It's at least as good as EG and SFTD, and easily better than anything el...
by Herman
Tue Dec 16, 2008 10:47 pm UTC
Forum: Serious Business
Topic: Unethical careers
Replies: 84
Views: 7807

Re: Unethical careers

Your standard of living isn't determined by how big the petrol-guzzling cock extension in your garage is, it is determined by how happy you are. If money made you happy, why would the richest country in the world also have one of the highest rates of antidepressant use? Because we can afford them. ...
by Herman
Tue Dec 16, 2008 7:50 am UTC
Forum: Serious Business
Topic: Unethical careers
Replies: 84
Views: 7807

Re: Unethical careers

Your standard of living isn't determined by how big the petrol-guzzling cock extension in your garage is, it is determined by how happy you are. If money made you happy, why would the richest country in the world also have one of the highest rates of antidepressant use? Because we can afford them. ...
by Herman
Tue Dec 16, 2008 3:13 am UTC
Forum: News & Articles
Topic: Bush attacked with shoes
Replies: 95
Views: 8244

Re: Bush attacked with shoes

Nougatrocity wrote:
Marbas wrote:Austin Powers, the answer to your question is JOURNALISTS.


Spoiler:
"Who throws a show? Honestly." -Austin Powers


You messed up the quote with a typo, but...

HOW DID IT TAKE THIS LONG FOR THIS REFERENCE!?


I went on this thread with the express purpose of making that reference. Damnit. :)
by Herman
Sun Dec 07, 2008 5:25 am UTC
Forum: Science
Topic: Chemical potential of excited states
Replies: 7
Views: 1095

Re: Chemical potential of excited states

Okay, so I came up with another way to think of this. The problem I was working on concerned a group of N two-level systems with the same energy gap u. So there's two ways to think of this: 1. There are N particles, each trapped in a two-level system. The total number of particles remains fixed at N...
by Herman
Sat Dec 06, 2008 11:15 pm UTC
Forum: Mathematics
Topic: Theorems named after the wrong people
Replies: 21
Views: 8570

Re: Theorems named after the wrong people

This isn't math, but, from Wikipedia: Dirac was also noted for his personal modesty. He called the equation for the time evolution of a quantum-mechanical operator, which he was the first to write down, the "Heisenberg equation of motion". Most physicists speak of Fermi-Dirac statistics fo...
by Herman
Fri Dec 05, 2008 5:22 am UTC
Forum: Science
Topic: Chemical potential of excited states
Replies: 7
Views: 1095

Re: Chemical potential of excited states

Hmm... I'm not sure that I get it. Why doesn't a photon from a de-excitation count as energy?
by Herman
Thu Dec 04, 2008 8:37 pm UTC
Forum: Science
Topic: Chemical potential of excited states
Replies: 7
Views: 1095

Chemical potential of excited states

Quick question: I remember hearing at some point that the chemical potential of an excited state is 0. The handwaving argument went something like "there is no 'pressure' on the system to create an excited state," or, um, something. So, assuming it's true that the chemical potential for ex...
by Herman
Sun Nov 30, 2008 4:35 am UTC
Forum: Science
Topic: You might be a physics major if...
Replies: 540
Views: 61390

Re: You might be a physics major if...

You know that when it comes to dirty-sounding physics terms, Uranus has nothing on stimulated emission.
by Herman
Mon Nov 24, 2008 2:36 am UTC
Forum: Serious Business
Topic: Effects of Population Growth / Decline
Replies: 138
Views: 14036

Re: How to solve the problem of low birth rate

Japan is a special case. Men and women in Japan simply aren't having sex. This is the result of centuries of male aggression toward and subjugation of women. It has nothing to do with the wider global trend of industrialized nations breeding at slower rates.


Wait, really? Source?
by Herman
Mon Nov 24, 2008 12:28 am UTC
Forum: Science
Topic: Scattering cross-section and interaction potential
Replies: 6
Views: 1282

Re: Scattering cross-section and interaction potential

Okay, thanks.

Edit: How can you tell they're actually talking about the quantum cross section?
by Herman
Sun Nov 23, 2008 11:32 pm UTC
Forum: Science
Topic: Scattering cross-section and interaction potential
Replies: 6
Views: 1282

Re: Scattering cross-section and interaction potential

I was overthinking the question. Here is is, verbatim from the book: For this kind of force... "Use arguments of dimensional analysis to show how the total scattering cross section of the molecules depends on their relative speed. Cross section only depends on the relative speed, molecular mass...
by Herman
Sun Nov 23, 2008 12:09 am UTC
Forum: School
Topic: Applications 2009
Replies: 49
Views: 4131

Re: Applications 2009

Yeah, it's that time again. Only this time, I actually have to do the applications rather than just chuckle privately at everyone who has to do this. Looking into Chemical Engineering, but we'll see about that. I'm in central jersey, I'm looking for a college with a strong engineering program in ge...
by Herman
Sat Nov 22, 2008 4:23 pm UTC
Forum: Science
Topic: Scattering cross-section and interaction potential
Replies: 6
Views: 1282

Scattering cross-section and interaction potential

This is for homework, but I'm looking for backround info rather than the answer. In my Stat Mech class, we're doing a unit on scattering cross-sections. I understand the connection between area and probability, and we covered the hard-spheres approximation, which seems very simple. The book claims t...
by Herman
Sat Nov 22, 2008 2:00 am UTC
Forum: Science
Topic: Thermal Efficiency
Replies: 12
Views: 1523

Re: Thermal Efficiency

No, no. It's always possible to move heat up a temperature gradient, provided you put in work from an outside source, such as electricity from the wall. That's how normal AC's work, after all -- they move heat from a cold room to a hot outdoors. We're just moving the "outside" to a very sm...
by Herman
Fri Nov 21, 2008 11:54 pm UTC
Forum: Science
Topic: Thermal Efficiency
Replies: 12
Views: 1523

Re: Thermal Efficiency

Hehe. So after a few days, your room's nice and cool, but you've got a bottle of solar plasma sitting on your floor. Awesome.
by Herman
Fri Nov 21, 2008 3:24 am UTC
Forum: Science
Topic: Impulse of a Meteorite
Replies: 18
Views: 1466

Re: Impulse of a Meteorite

Sure, but that isn't really accomplishing anything as far as verifying the impulse-momentum theorem goes. If you're indirectly finding time using the same values that you're using in calculating the change in momentum, you're just calculating the same value twice. You're suggesting you're verifying...
by Herman
Thu Nov 20, 2008 5:38 am UTC
Forum: Science
Topic: Impulse of a Meteorite
Replies: 18
Views: 1466

Re: Impulse of a Meteorite

Nope. Out of the big five kinematics quantities, (starting speed, ending speed, acceleration, displacement, and time), you need three to find the other two. Each equation includes four variables, so you can solve for the two you need one at a time. In this case, time and acceleration, found from sta...
by Herman
Wed Nov 19, 2008 10:04 pm UTC
Forum: Science
Topic: Impulse of a Meteorite
Replies: 18
Views: 1466

Re: Impulse of a Meteorite

Right, I think he gets that. But he also has to find impulse by other means, and verify that the two answers match. The "other means" is what I'm hinting at above.
by Herman
Wed Nov 19, 2008 9:43 pm UTC
Forum: Science
Topic: Impulse of a Meteorite
Replies: 18
Views: 1466

Re: Impulse of a Meteorite

You don't need to measure the acceleration. You can calculate it, and the time it takes the ball to come to a stop, from the quantities you listed.

Stop thinking about calculating impulse -- you need acceleration and time, and you know how to find those.
by Herman
Wed Nov 19, 2008 2:05 am UTC
Forum: Science
Topic: Impulse of a Meteorite
Replies: 18
Views: 1466

Re: Impulse of a Meteorite

My only idea is to use the conservation of energy to find the velocity of the ball when it hits the dirt. Yes, do this. Knowing the mass of the ball, you now know the momentum of the ball in the instant before it hits. Considering that after it hits and digs a crater it has 0 momentum, you now know...

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