- My friend was trying to talk to me about atoms, but I got Bohr'd.
- Did you hear that Albert Einstein developed a theory about space? It was about time, too.
- Never trust an atom; they make up everything.
- The oddly pleasant feeling of looking down on a physicist as they finish the last of their drink. The strange charm of a top-down bottoms-up.
- Why does hamburger have less energy than steak? It's in the ground state.
- Why are physics books always unhappy? Because they're full of problems.
- Neutrinos make the worst friends; they rarely interact with anyone.
- In a quantum finish!
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- KK, Tekulo, and I are in the same house again. This changes tomorrow, as KK and I are going to a friend's house, then KK returns to school.
- Had a New Year's Eve celebration with friends from college. Had a blast.
- My Christmas gifts include Super Mario Bros. 3D World, the Winter Market LEGO set (which I may trade with KK for his Winter Village Cottage, which I like a lot), a Fluttershy (my third so far), the mini-VW camper LEGO set, and a ceramic Snoopy sitting on his doghouse. All in all, a good haul.
or, in component form,
The word "virial" comes from the Latin vis, which means "force" or "energy," and looking at the equation, it makes sense why it's called that. Here the big Σ means sum, the "k" index denotes the kth particle of a system of N particles, V is the potential energy function affecting the kth particle, T is the potential energy of all the particles in the system, and rk is the position of the kth particle. This essentially relates the kinetic energy of all the particles to the positions and forces exerted on each particle (since -grad V is the force when energy is conserved, which is an assumption we are making). The brackets 〈 〉 denote that we're taking an average, so 〈T〉 is the average kinetic energy, etc.
Now, you may be thinking, "okay, that's a cute equation, I guess, but I don't see how it's particularly useful." Okay, here's where the usefulness comes in. Let's say I want to know the mass of some distant galaxy, but I don't have a good galaxy-weighing device on hand. We know that the gravitational potential energy of an object is given by
where m is the mass of the star, M is the mass of the center of the galaxy, and r is the distance from the center of the galaxy. Taking the distance r and multiplying by the gradient of the potential yields...the potential again, with a negative sign out front. So, for gravity,
Plugging this into the Virial theorem above and noting that 2T = mv^2 (where v is speed), we get that, for an object in the gravitational pull of an object of mass M,
Thus, we have at our disposal a way of measuring the mass of something like a galaxy by measuring only the speeds of stars and their distance away from the center. That's pretty incredible.
This actually is one of the ways scientists support the idea that there is dark matter in the universe; the Virial theorem gives an average of what speeds the stars in our galaxy should have based on their distance away from the center of the Milky Way, but what we actually observe is startlingly different. Thus, we can conclude that something is wrong with our knowledge of how gravity within a galaxy works. Based on this and other observations, the idea that there's extra stuff that can't be seen that adds to the gravitational force of a galaxy seems to be a reasonable idea.
In my research on diatomic hydrogen (H2), the Virial theorem is used in a different capacity. When figuring out the potential energy of an electron (or two) around the two positively charged protons, the virial has the Coulomb force term (which is just -V, just like gravity) and an additional term that pops up from assuming that the electrons are keeping the protons at equilibrium. I won't go too much into the physics, but the final product is
where E, T, and V are the total energy, kinetic energy, and potential energy of the electron(s), respectively, and R is the distance between the nuclei. This tells us something useful about the energy of the electrons; more specifically, it tells us about how the energy changes as you move the nuclei farther apart or closer together. In other words, since E = T + V,
which is very useful when constructing potential energy curves for hydrogen.
On a slightly related note, our lab's paper got published! Akano is now a for reals, published scientist! 8D
I have become a consecutive fishing master! I want to get a shiny Corsola next.
Also, I had a very enjoyable Thanksgiving with my family and our friends. Tomorrow I head back to my apartment, and then Monday is school as usual.
Also, I caught a shiny Ditto in Pokémon Village. Luckiest chain ever (I definitely did not get a chain of 40...).
On a more jubilant note, I've been playing Pokémon Y and Ace Attorney: Dual Destinies recently (this is in no way like Tekulo's recent entry). I'm on the first part of case three of the latter, and I have to say that case two was very enjoyable. The twist was really good, and all the crazy weirdness of the people in that case now makes sense (it kind of reminds me of Turnabout Big Top from Justice for All).
In Pokémon Y, I have gotten through Victory Road and am now ready to face the Pokémon League:
Also, I think it's fantastic that I can customize my character with a yellow hoodie and well-matching fedora.
My party currently consists of Keaton (Delphox), Anubis (Lucario), Lapras, Sylveon, Snorlax, and my HM user (a linear combination of Machoke, Talonflame, Pansage in near equal probability). I absolutely love the fact that the Fennekin family is based on mages, and Sylveon is absolutely fantastic. Since evolving it, I don't think I've had it faint once.
EDIT: Also, apparently this is my 200th entry! This is a milestone for some reason!
As you may have noticed, I've been kinda away from BZP recently due to the wonder that is me being in grad school. Last month began my third year into the foray of graduate studentdom, and since then I've been up to the following:
- Taking Thermodynamics/Statistical Mechanics (four lectures a week spread across Thursday and Friday)
- T.A.'ing three sections of introductory physics lab
- Doing research (My group recently submitted a paper which we have gotten back with editing suggestions. We're going to resubmit tomorrow and hopefully get published! I'm going to be a for-reals published scientist!)
- Buying a Wii U bundled with The Legend of Zelda: Wind Waker HD (Pictures of the awesome GamePad will follow. As of this writing, I have just beaten Gohdan)
- Finding out exactly what a true Hufflepuff is, anyways.
I'm very happy with the improvements made in the game. If only there weren't so much BLOOM (it's not that bad, though).
Akano Toa of Electricity
Stone Champion Nuva
+2 for Premier Membership
+1 from Pohuaki for reporting various things in Artwork
Real Name: Forever Shrouded in Mystery
Likes: Science, Math, LEGO, Bionicle, Ponies, Comics, Yellow, Voice Acting
Notable Facts: One of the few Comic Veterans still around
Has been a LEGO fan since ~1996
Bionicle fan from the beginning
Misses the 90's. A lot.
Hieroglyphs And The Like
Equation of the Day #12: MassUnikitty Tekulo - Apr 15 2014 03:01 PM
Equation of the Day #11: The Uncertainty PrincipleObsessionist - Apr 12 2014 09:12 AM
Equation of the Day #10: Triangular NumbersAkano Toa of Electricity - Apr 06 2014 04:50 PM
Equation of the Day #10: Triangular Numbersxccj - Apr 06 2014 10:44 AM
Equation of the Day #10: Triangular NumbersGatanui - Apr 06 2014 09:19 AM