## Search found 289 matches

Wed Aug 12, 2009 4:16 am UTC
Forum: Science
Topic: Why is there no "center" of the universe?
Replies: 60
Views: 7763

### Re: Why is there no "center" of the universe?

Okay, back on topic, is there a center in more dimensions? The 2d surface of a balloon has a 3d center. Is there a 4d center of the universe? Any 4-sphere has a center. In the case of the model we're using, the fourth dimension is time, and the center is when t=0, or teh big bang. Not so fast. Any ...
Tue Jul 21, 2009 4:04 pm UTC
Forum: Science
Topic: Quantum Entanglement
Replies: 64
Views: 8258

### Re: Quantum Entanglement

Still cannot comprehend why they just don't have opposite spins anyway. That's a whole lot simpler than all this Quantum entanglement. (some phrase about a razor springs to mind ;) ) Why is the spin undetermined at 50/50 up or down. Why can it not be "we have made a particle with up" spin...
Wed Jun 03, 2009 4:33 pm UTC
Forum: Science
Topic: A quantum mechanics question.
Replies: 5
Views: 953

### Re: A quantum mechanics question.

Looks good to me too
Tue May 26, 2009 10:58 pm UTC
Forum: Science
Topic: What is the hottest possible temperature?
Replies: 28
Views: 13938

### Re: What is the hottest possible temperature?

It may help to know that both energy and momentum are infinite for a particle moving at c.
Tue May 19, 2009 6:25 pm UTC
Forum: Science
Topic: Projectile Motion w/ Drag... help?
Replies: 15
Views: 3650

### Re: Projectile Motion w/ Drag... help?

I believe this problem is unsolvable exactly. We did this problem in intermediate mechanics in college and were forced to use perturbation theory to find an approximate solution, the limit of which to infinite order is the exact solution.
Thu Apr 30, 2009 1:31 pm UTC
Forum: Science
Replies: 6
Views: 1247

O whoops I didn't see that you assumed a constant jerk.

As a side note, I just noticed if you keep doing this you get a Taylor series, and that method is a good way to derive the Taylor series. (This may be the only way to derive it but I always forget how it was taught in class).
Thu Apr 30, 2009 3:44 am UTC
Forum: Science
Replies: 6
Views: 1247

There are only 1 set of equations for constant acceleration. There is an infinite number of possible accelerations. The way to get the equations of motion is by integrating acceleration to get velocity, and then integrating velocity to get position.
Thu Apr 23, 2009 8:11 pm UTC
Forum: Science
Topic: Fun things to do with dry ice?
Replies: 17
Views: 5561

### Re: Fun things to do with dry ice?

As long as it's clean, I like to put it in drinks. It makes for a fun party actually. As for science, meh I dunno.
Tue Apr 14, 2009 2:50 pm UTC
Forum: Science
Topic: Physics(Mechanics) problem I'm having some trouble with...
Replies: 10
Views: 1855

### Re: Physics(Mechanics) problem I'm having some trouble with...

Well then, everyone is wrong except you. Congrats!

And to whoever marked the test, the beauty of physics is that you can prove them wrong by showing them what the moment of inertia is for your answer. They can't argue with math.
Tue Apr 14, 2009 2:46 pm UTC
Forum: Science
Topic: How to make the maximum amount of ice melt?
Replies: 14
Views: 1818

### Re: How to make the maximum amount of ice melt?

Does this mean that having the drink as cold as possible is the same goal as having as much ice melt as possible? Not if the ice is below freezing. If the ice is below freezing and you put a sufficient amount in (and let's assume that every point in the ice cube will be at the same temperature), th...
Sat Apr 11, 2009 4:36 pm UTC
Forum: Science
Topic: Physics(Mechanics) problem I'm having some trouble with...
Replies: 10
Views: 1855

### Re: Physics(Mechanics) problem I'm having some trouble with...

Are you sure you aren't looking for the least angular acceleration?
Sat Apr 11, 2009 4:34 pm UTC
Forum: Science
Topic: How to make the maximum amount of ice melt?
Replies: 14
Views: 1818

### Re: How to make the maximum amount of ice melt?

If the liquid gets too cold though then its done its job. You want to melt the most ice, not the highest fraction of it. The liquid has a fixed amount of energy that it can give up before it is 32 degrees. Once it gives that up, no more ice will melt (excluding heating from the atmosphere). So once ...
Sat Apr 11, 2009 5:34 am UTC
Forum: Science
Topic: How to make the maximum amount of ice melt?
Replies: 14
Views: 1818

### Re: How to make the maximum amount of ice melt?

The best way to allow for all of the above is to slowly pour crushed ice into the glass while stirring. I don't know about slowly. Sure a single ice cube might melt slower, but you have more ice cubes. It is really down to total surface area touching liquid. Of course you want the ice at 32 degrees...
Sat Apr 11, 2009 5:22 am UTC
Forum: Science
Topic: Physics(Mechanics) problem I'm having some trouble with...
Replies: 10
Views: 1855

### Re: Physics(Mechanics) problem I'm having some trouble with...

I believe you are correct but it's late so I may be wrong. You are correct that you want the lowest moment of inertia, and you're friends seem to be choosing the highest.
Sat Mar 28, 2009 5:12 am UTC
Forum: Science
Topic: Magnets and Their Fields!
Replies: 7
Views: 1063

### Re: Magnets and Their Fields!

edit: sorry I thought I knew but I think I convinced myself I didn't
Thu Mar 19, 2009 8:22 pm UTC
Forum: Science
Topic: Science and Misery
Replies: 57
Views: 4798

### Re: Science and Misery

But is it not also true that science deprives one of certainty? That from the scientific point of view, even though you can establish a pretty good trend in things, you can never be sure that tomorrow something might very well come along and force you to throw away (or at least heavily revise) ever...
Wed Mar 18, 2009 2:14 pm UTC
Forum: Science
Topic: Science and Misery
Replies: 57
Views: 4798

### Re: Science and Misery

I would hate to be certain all the time. I can't imagine living a life where I don't try to learn something new or explore new possibilities. Life would be too boring if I was certain about everything. Science can be a form of adventure. It's partly about the end goal, but the act of doing it is rew...
Tue Mar 17, 2009 8:22 pm UTC
Forum: Science
Topic: Chemistry Demonstrations
Replies: 56
Views: 5993

### Re: Chemistry Demonstrations

I'm no chemist, but if you take pure sodium and put it in a beaker full of water (put it in a big sink), the beaker will shatter if you put enough sodium in. Don't know if they want you breaking their lab equipment though. If you do it with a small amount the sodium will just burn and spin around in...
Tue Mar 17, 2009 12:42 pm UTC
Forum: Science
Topic: Is there a law of perspective?
Replies: 5
Views: 2315

### Re: Is there a law of perspective?

Yes. Read about solid angle http://en.wikipedia.org/wiki/Solid_angle It is not exactly what you mean by a measure in meters how big it looks, because then you'd have to define what a meter looks like (how far away do you stand from the meter before you look at it?). Instead you can define a perspect...
Fri Mar 13, 2009 7:34 pm UTC
Forum: Science
Topic: Expensive Colleges
Replies: 24
Views: 2652

### Re: Expensive Colleges

I tend to prefer going for the cheaper alternative as long as it is still a good school. I chose going to Boston University over an ivy league school because I got a scholarship. I found it to be a great school that is easily competitive with the so called "better" schools. As long as you ...
Mon Mar 09, 2009 3:53 pm UTC
Forum: Science
Topic: Science Conferences
Replies: 12
Views: 1648

### Re: Science Conferences

I will be at the SPS (Society of Physics Students) conference at Boston University at the end of the month, and the CLEO (Conference on Lasers and Electro-optics) in May/June. Anyone else going to be there?

Sadly I wont be at any of the conferences previously mentioned.
Tue Mar 03, 2009 9:56 pm UTC
Forum: Science
Topic: Infinite Grid of Springs
Replies: 14
Views: 2507

### Re: Infinite Grid of Springs

The force would not be infinite because there will be a characteristic speed (much like the speed of light) in the problem, making only a finite number of springs affect a given point in time.
Tue Mar 03, 2009 1:50 am UTC
Forum: Science
Topic: Electric Field in a Dipole falls off as r^3?
Replies: 6
Views: 3185

### Re: Electric Field in a Dipole falls off as r^3?

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

The electric field from a point charge drops off as r^2. A pure dipole has no net charge, so acts differently. You will find this extends to 2^n poles.
Tue Mar 03, 2009 1:46 am UTC
Forum: Science
Topic: Infinite Grid of Springs
Replies: 14
Views: 2507

### Re: Infinite Grid of Springs

Locally Im not so sure, but if the size of the gap between springs was very small compared to your area of interest, wouldnt it act much like the 2D wave equation? You would have an initial position and velocity at every point and have outward propagating longitudinal and transverse waves. The speed...
Thu Feb 19, 2009 7:41 pm UTC
Forum: Science
Topic: batteries, electric potential and current
Replies: 9
Views: 1069

### Re: batteries, electric potential and current

Electrons flow from the negative terminal to plate L, making it negatively charged. The positive terminal "pulls" electrons out of plate H making it positively charged. From what I can tell the book is correct, but worded in a confusing manner.
Sat Feb 07, 2009 8:38 pm UTC
Forum: Science
Topic: Hamiltonian and Lagrangian Mechanics
Replies: 6
Views: 1237

### Re: Hamiltonian and Lagrangian Mechanics

In classical mechanics, Lagrangians are used to simplify complex force problems, so you don't have to worry about force at all. Instead of considering all possible forces in a problem, all you need is potential and kinetic energy. This can be reduced, as stated by Klotz, to a differential equation t...
Wed Feb 04, 2009 6:19 pm UTC
Forum: Science
Topic: You might be a physics major if...
Replies: 540
Views: 61897

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

YMBAPM if when someone says: "I weight 80Kg" you want to stab them. Honestly, I don't know a single physicist who would give their weight in Newtons. I don't have a problem with saying it: it's not like it's ambiguous, provided you assume everybody's on the same planet. [pedantry] On the ...
Wed Feb 04, 2009 6:16 pm UTC
Forum: Science
Topic: How to win an arguement with an anti-creationist.
Replies: 45
Views: 3707

### Re: How to win an arguement with an anti-creationist.

I think people need to be persuaded that the scientific method is valid, and only then can appreciate or be educated about scientific findings. This explains why all the "evidence" for ID is always flawed. It is either malicious, or just people trying to get across to us scientific method ...
Mon Feb 02, 2009 4:28 pm UTC
Forum: General
Topic: Topics that make your brain hurt
Replies: 31
Views: 3018

### Re: Topics that make your brain hurt

I have often come across topics like this in my research, and I have a theory about why it is. I think there is a part of our brains that thinks about things we do not yet understand. It is very easy to wear this part out. I have found that once I realize that I do understand the topic more than I p...
Mon Feb 02, 2009 3:28 pm UTC
Forum: Science
Topic: You might be a physics major if...
Replies: 540
Views: 61897

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

If I am ever a math/physics professor, whenever I have to use 2 variables I am going to use zeta and xi just to torture students. I can see it now, just a series of squiggles that's supposed to mean something...
Mon Feb 02, 2009 3:26 pm UTC
Forum: Science
Topic: Le Chatelier's Principle
Replies: 7
Views: 1411

### Re: Le Chatelier's Principle

As a general rule, all simple principles break down at extreme temperatures/pressures etc. I am no chemist so I am not sure what this principle is, but rest assured at extremely high pressures it will not work correctly. (I am talking near infinite pressure about which current science cannot even sp...
Mon Feb 02, 2009 1:06 pm UTC
Forum: Science
Topic: You might be a physics major if...
Replies: 540
Views: 61897

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

You might be a Physics major if you know the Greek alphabet better than the Latin one. On a side note, the margins of all my first-year Physics notes were covered in me practising new letters that I wasn't familiar with. Lowercase Phi, now there's one I spent a while on. And I still can't do a prop...
Fri Jan 30, 2009 1:07 pm UTC
Forum: Science
Topic: Electric Field Due To A Mobile Phone...
Replies: 4
Views: 862

### Re: Electric Field Due To A Mobile Phone...

how is skin depth defined? How could you use that information to find the strength?

hint: exponential decay.
Wed Jan 21, 2009 2:11 am UTC
Forum: Science
Topic: Achieving very low temperatures
Replies: 8
Views: 1771

### Re: Achieving very low temperatures

Often in experiments liquid helium is used, but that is around 4K. This of course does not explain how the liquid helium was made. Kind of a useless response... Sorry.
Tue Jan 20, 2009 8:44 pm UTC
Forum: Science
Topic: Weight of an Hourglass
Replies: 69
Views: 8549

### Re: Weight of an Hourglass

Well the impact and the effect of the weightless sand would not exactly cancel, as the impact force depends on the height the sand falls, while the weightless sand effect depends only on the mass of the sand and the rate of flow, so there will be some variation. Im not exactly sure how the math woul...
Wed Jan 14, 2009 5:12 am UTC
Forum: Science
Topic: Do you ever get tired of being asked why?
Replies: 29
Views: 3250

### Re: Do you ever get tired of being asked why?

I would make up slightly insulting responses that have nothing to do with the thing they are asking you about.

example:

Q: Why did you build that capacitor?
A: Because I couldn't figure out how to build something that asks me stupid questions.
Mon Jan 12, 2009 2:19 am UTC
Forum: Science
Replies: 41
Views: 4889

All this makes me think, that if the universe is paradox free, then traveling back in time is impossible, or there is an infinite number of universes. I claim the former is more likely, and therefore the solution, unless somebody has evidence of multiple universes. And those who respond that relativ...
Thu Jan 08, 2009 3:55 pm UTC
Forum: Science
Topic: LHC Dangerous?
Replies: 372
Views: 86139

### Re: LHC Dangerous?

Here's a question. Why would a black hole the mass of a few protons be dangerous? Afterall, black holes' only power is their gravity. Also, a point of my own confusion. What is the definition of a black hole when protons are considered point masses anyway? Is it just a bunch of protons held together...
Thu Jan 08, 2009 3:45 pm UTC
Forum: Science
Topic: The fastest you can go.
Replies: 24
Views: 2223

### Re: The fastest you can go.

I think the important distinction is that the spaceship is not making the Earth's time go faster. According to the Earth, the ship will take d/v time to get there, same as always. The faster the ship, the less time it takes to get there.
Thu Jan 08, 2009 3:40 pm UTC
Forum: Science