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Saturday, January 11, 2014

Fixin' Up the Confusion Between Mass, Weight, Volume and Density

    Alright, so this isn't a typical post.  It's more of a guide to some terms I'm going to be using in later posts, so if anybody gets stuck on one of these terms they can always refer back to this article.  Also, if I use a term you don't understand or you hear somebody use a term you are unclear with, you can always e-mail the word(s) to me at and I can make a follow-up guide.
    Okay, so our vocabulary today is four easily confused words: mass, weight, volume, and density.  The two most confused are mass and weight, and some people use them interchangeably, when in actuality they're not interchangeable.  In layman's terms, mass is how much stuff there is and weight is how heavy the stuff is.  For instance, if I pour equal amounts of oil and water into a bottle, they should mix together, because they have the same amount of "stuff," right?  Well no, because although they have the same mass (how much of each liquid is in the bottle) the molecules of water, on a microscopic scale, are more closely packed together than the oil molecules, which are more free.  Because the water has more molecules packed together, it has more weight, even though we poured equal amounts of oil and water into the bottle.  So the takeaway from this is that although each liquid has the same mass in the bottle, they weigh differently, so the oil rises and the water stays at the bottom.
    What about volume and density?  So volume is basically how big the inside of something is.  A simple hut has a relatively small volume compared to Carlos Slim's (the richest living man who makes his money off of the Mexican telephone system) mansion.  Density is a bit harder to understand.  If you have to read this part twice, it's okay, because I also had trouble figuring out density when I first learned about it.  Here goes:  Basically, density is how heavy stuff is per a volume of stuff.  Confusing, right?  Have you ever wondered why a muscular dude weighs more than a fat guy who has the same amount of fat as he has muscle?  The answer is density.  Density is how many molecules are in a certain volume.  If I make two boxes of exactly the same size and take muscle and fill one of the boxes to the very top with it, and I do the same with the fat, I have two boxes of equal volume holding amounts of muscle and fat that are equivalent in mass.  However, the muscle weighs more because the molecules in the muscle fibers are much more closely packed together than the fat molecules.  This says that the muscle has a higher density, because the mass per volume in muscle is greater than fat, so although there's equivalent mass and volume, their weights are different.  This is the same with oil and water.  Oil is less dense, so if I have equal masses of oil and water, oil rises to the top.  Density is measured in units of mass per units of volume, so to understand it, you have to understand the other three terms mentioned previously.  So there you have it: mass, weight, volume, and density.

Monday, August 12, 2013

Why Laser Quest Employees Should Stop Pretending They Have PhDs in Astrophysics

Today our story starts after sailing camp and lunch.  My friends from Maryland are visiting us, and we went with them and their cousins to Laser Quest, a laser tag place in Danvers.  After we got our scorecards for the first round, the guy who gave us them asked us to quiz him.  He got questions including "What are the names of the Seven Dwarves?" and "Who are the five presidents on Mt. Rushmore?" and "When did John Adams die?"  After more easy presidential nonsense, I decided to take it up a notch.  After giving everybody who questioned him prizes because he DID get them right, he didn't give me a prize when I actually stumped him with a differential calculus question ("What is the limit as x approaches 2 of x - 2/x - 2?").  Who is this guy, giving prizes to people who can't stump him and not to somebody who does?  Next, he said "Now I got a question for you people.  After our sun explodes in a supernova, what happens?"  After being stumped with one of the easiest calculus questions there is, Mr. Laser Quest Employee still thinks he's the next Stephen Hawking.  The first thing that ran through my head was "Supernova... Oh, yeah a white dwarf star."  But then I realized what would actually happen first to our sun.  I raised my hand and said "A nebula."  Then he said "No, Okay, next answer."  Then my friend said "Your question is incorrect becau-" 
"Okay, next answer."  Then some teenager said "White dwarf?"
"Yes! Here's your prize!"  He then handed him some tchotchke rubber ball.  The guy was sort of right, but my friend and I were more right.  

Now I will explain why this guy doesn't have his facts right.  Only supergiant and hypergiant stars the size of our galaxy can burst into supernovae.  Our sun will eventually turn into a white dwarf, but with no supernova and after a planetary nebula is formed, like I said.  Let's get started.  In around 5.4 billion years, the Sun will exit its main sequence, which is basically no more of the Sun we know today, getting brighter and bigger.  The first stage will be when it is a subgiant.  This will happen when it has burned up all of its hydrogen fuel after that 5.4 billion years.  During about a half billion years in this subgiant stage, it slowly expands to two times its current size, engulfing the inner planets, including Earth.  After another half billion years, it expands much more rapidly to two hundred times its current size and a few thousand times its current brightness.  It then starts to become a red giant, entering the red giant branch (RGB).  RGB is pretty boring, where the really fat Sun just sits there for a billion years and loses about a third of its mass.   It now only has 120 million years left.  In a few seconds, something called a helium flash occurs where a lot of helium is burned.  In the helium flash, the star contracts because gravity is pushing it in.  Stars don't collapse once they form because they're vey hot, and heat gives pressure.  Once it exhausts all this thermal energy, the star becomes what's called degenerate matter, or Fermi gas.  The heat stops supporting the star, and that's where quantum mechanics works its magic.  Something called the Pauli exclusion principle says that two fermions (certain particles including electrons) cannot be in the same quantum state, which is the exact energy of it.  The degenerate matter is cold, so the atoms enter all the lowest quantum states.  This degenerate matter is so dense that it is easy to find the position of every atom.  The Heisenberg uncertainty principle then says that since we know an atom's position so well, we must know very little about its speed.  We only know that, on average, the degenerate matter atoms are whizzing around near the speed of light.  If another atom is introduced, it is hard for it to assume a low-energy quantum state since all the other atoms already have "dibs" on these states.  After this quantum mechanical pressure, gravity overcomes it and shrinks the Sun, reverting it to only 10 times its current size and only 50 times as bright.  It then enters the horizontal branch (HB).  It basically expands after losing all its helium fuel like it did before RGB, except this time the Sun is bigger and brighter.  This is now the asymptotic giant branch (AGB).  The sun will become very unstable after 20 million years of AGB.  It will become bigger and brighter each time it expands.  This expanding and contracting, called thermal pulsing, will happen to our sun about four times before it loses all its outer mass, which forms a planetary nebula, a giant gas cloud of hydrogen and helium that can form new stars and planets.  The very hot, naked core will finally cool to form a white dwarf, which is where the teenager kind of got it right.  The nebula will survive for only 10,000 years (very short on the cosmological time scale), whereas the white dwarf will survive for trillions before fading to a black dwarf.  Was I going to explain this to him? Definitely not.  I had some laser tag to play!

Thursday, June 27, 2013

Quantum Tunneling, Friends Running Into Walls, and The Flash

Dear Readers,
School is over, and my most stressful term of the year is finally done, so I can go back to blogging.  Today our story starts off after my Science Olympiad enrichment.  I was preparing for a forensics event with my friend Cole, who is always looking for the "cool" side of science.  Soon enough, he would learn a REALLY cool bit about quantum mechanics.  It is called quantum tunneling, and both superheroes and microscopes use it.  Basically, when a fat guy like the one above runs into a wall, he isn't going very fast, and his electrons are not in an energetic state.  Quantum tunneling says that the Batman shopper guy has a small probability of tunneling through the wall by borrowing energy from around him and transporting to the other side of the wall because of the quantum probability that he could be on the other side.  He has a more likely chance of getting through if a) the wall was thinner and b) he was faster.  If Usain Bolt did it, he would have a slightly higher percentage of making to the other side, but still only about a trillionth of a percent of the speed of light.  When Flash does it however, he raises himself to 99.99% the speed of light, and now he's practically certain to go through the wall.  If I walked into a wall 10 times every second, it would take me the whole life of the universe to have a fantastic chance of going through the wall.   So I tell Cole about quantum tunneling. This is where I start watching my friend walk into a foam pad for 3 straight minutes.  Mr. Blakney says "Cole, why are you walking into a wall?"  Cole then mutters "Quantum tunneling."  Mr. Blakney gives me a strange look, hearing the word 'quantum' mentioned.  He knows I am partially causing Cole to walk into a wall.  I explain to Mr. Blakney what quantum tunneling is.  He approves.  I then end up explaining it to Mr. Sullivan.  Then I hear Cole declare with glee "Only 13.7 billion more years!".  Sounds practical, huh?  Not really.  But quantum tunneling does have many practical applications, one of which I will explain.  The STM, or scanning tunneling microscope, uses quantum tunneling to make a detailed drawing of a surface.  Its tip touches the very surface of the material, usually metal.  But it only touches the electron clouds of the top layer of atoms, so not the actual surface.  It sends an electrical current through the tip and "feels" the electrons by detecting changes in the current.  It then maps out each individual atom on a computer to compile a close-up image. I hope this was fun and please, the life of the universe is kind of a long time, so don't think you can tunnel through your little brother whenever you want (I wish that were true!).

Tuesday, January 29, 2013

Dear Readers,
It has been so long since I updated, but I knew what I was going to do for a while. I am posting my first article for that fifth-grade newspaper I told you about. I couldn’t update sooner because there were a lot of things in question previously, but hopefully the first issue will be published this week. I would like to dedicate this article to my Step-grandmother Martha, one of the most compassionate, forgiving people I knew, who has just recently passed away. Here is my article:

Science, Math and Technology

The Photoelectric Effect

1905... a very important year in science, with all sorts of breakthroughs from the idea of golf ball dimples to The Third Law of Thermodynamics by lesser known Walther Nernst. But, 1905 was most important for our favorite stereotypical scientist dude: Albert Einstein. He came up with Special Relativity (coming up with General Relativity ten years later in 1915) and Brownian motion.

There is one more major discovery he came up with: yep, you guessed it; the photoelectric effect. “Photo” is the Latin root for light, and electric has to do with electricity and the flow of electrons.This is exactly what the photoelectric effect is about. (Always trust Latin to decipher a really science-y word!) Here’s the main idea. Some physicists wre experimenting with light waves by shooting them at metal plates and trying to coax the particles that spin around the center ball (the nucleus) of an atom: electrons. They found that they couldn’t get electrons to come out until they started experimenting with higher energy waves in the ultraviolet spectrum of light. 

We can only see a small fraction of light waves because our eyes evolved to our necessities. Lower and higher frequencies of light, like microwaves, gamma waves, and ultraviolet waves are some examples of waves we can’t see because their frequencies are too high or too low. A thermal camera can “see” ultraviolet radiation and use its program to convert the image into a color coded image in our visible light spectrum. 

Some animals, like snakes, see higher frequencies too because they’ve had to adapt to being able to find small prey, so it helps to have a built-in thermal camera. What the scientists found was that when they bombarded the plates with higher energy ultraviolet waves, the plate surprisingly emitted electrons, unlike their unsuccesful experiment with lower frequency light. Furthermore, if they shot 1000 lower-frequency light waves the plate didn’t emit electrons, but even with a few ultraviolet waves the plates did emit electrons. They were stymied. 

Of course Einstein heard about this, and he started working on it. He eventually figured it out and published a paper about his findings in the magic year of 1905. He basically said that no matter how many low-frequency waves you shoot, there isn’t any sufficient energy to knock the electrons out of their orbits. Once you take out the big guns (ultraviolet waves), there’s definitely enough energy to make some electrons go flying. 

In my words, if you poke my brother in the morning, he will fail to wake up, no matter how many times he is poked. If you give him a nice, crisp thwack though, he will definitely wake up. (You can rest reassured: no brothers were harmed in the writing of this article.) The physicists confirmed Einstein’s work.  An example of the photoelectric effect is when soldiers use night-vision goggles at night. Photons (particles of light) hit a metal in the visor such as gallium arsenide and create photoelectrons. These photoelectrons then hit a phosphor coated screen and turn back into photons, making the soldiers able to see. Next time, I think we’ll be talking about Vedic division, and I’ll see you then.

Monday, December 17, 2012

Dear Readers,
My friends and I are starting a student-run school newspaper for our school, MCCPS. I'm going to be writing the science column of the paper and I will mostly write articles about our favorite subject, quantum mechanics. I am going to publish them to my blog as a bonus to my regular blog entries. Enjoy!

Sunday, November 25, 2012

Mitchell's CliffNotes of CMR

     What is gravity, really?  Okay, it made the apple fall off the tree and bonk Sir Isaac Newton’s head. It makes everything fall back to Earth. There have been a lot of theories for gravity, but the most plausible is relativity. Relativity incorporates many concepts, and conveniently, one of them is gravity. Albert Einstein, the creator of General and Special Relativity, made one of the two variations of relativity, STR (Space-Time Relativity). In STR, space and time are one; a fourth dimension, if you will. In this theory, an invisible “blanket”, called the space-time continuum, is the medium in which relativity works. The more massive an object is, the more it causes a depression in the “blanket”. If a watermelon is the sun and a blanket is the space-time continuum, then if you put the watermelon on the blanket it causes a depression proportional to its mass. Furthermore, an object with mass less than or equal to another object’s mass will be gravitationally attracted toward that object if it’s close enough. If I were to put an orange on the blanket, it would cause a depression proportional to its mass, and if close enough would roll towards the watermelon. An apple is less massive than our planet, and it is definitely close enough to have a gravitational attraction to Earth. If it’s attracted it will move towards the Earth’s center, so when the tree’s branches become too weak, gravity takes over.
     Should we believe in this theory? After all, it is very plausible. I loved it until Black Friday came along. I went to Brookline to visit my grandfather, Grandpa Charles, and his wife, Martha. I also met a guy whose parents were told by his grade school teacher he was “feeble-minded” (He ended up graduating at Harvard University and becoming a professor there.). I thought STR was the only theory of relativity until Grandpa Charles told me otherwise at Panera. In 2008, a man named Edward Apgar created a new theory of relativity explaining gravity called CMR (Charge-Mass Relativity). I thought STR was the only theory of relativity there was, so I didn’t bother calling it STR. I just called it relativity. But apparently a new theory of relativity was created four years ago. I couldn’t believe I had first learned about the old relativity rather than the one. After all, CMR was out by the time I started learning about quantum mechanics (I did not start learning about physics when I was six!). Well, here is the story of CMR in “English”.
      An atom has a center ball of particles called a nucleus. The particles in the nucleus are the neutrally charged neutrons and the positively charged protons, which have a charge of about 1/2 (never mind the unit of measurement). Circling the nucleus are the negatively charged electrons, which have a charge opposite of the protons, equal to about -1/2. There are an equal amount of protons as there are electrons in an atom, so they should balance each other out giving the atom a neutral charge. Just like the same sides of a magnet repel each other, an electron-electron combo repel each other and a proton-proton pair repel each other. Also just like opposite sides of two magnets attract, an electron-proton pair or a proton-electron pair attract each other. In fact, magnets make use of protons and electrons. If two hydrogen atoms are near each other, each with one proton and one electron, they should not exert any attractions except gravitational attractions. The reason the atoms don’t repel because of the proton in atom 1 and the proton in atom 2 or the two electrons is because of the electric attractions. What about the proton in atom 1 combined with the electron in atom 2 or vice versa? These forces balance each other out. Done! Who needs CMR! Who even cares! Wait a second. Since when can we just assume that the attractive and repulsion forces are equal?! “Duhhhhh”, one might say. Duh what? That’s a nice assumption but physics isn’t perfect like that. Mr. Apgar found that the attractive forces between those atoms is slightly greater than the repulsion forces. This is an attraction, and gravity is an attraction. Essentially what my grandfather was saying was that gravity is not a force on its own, but rather a side effect of electric forces between atoms. And to finish it off, he whipped out a photocopy of the very CMR paper itself. This proves he isn’t just some guy making up some lunatic theory. He’s even met Mr. Apgar himself and PAM Dirac, one of the greatest physicists of all time. And by the way, my lack of updating has been inexcusable, even with my business. My next entry will be much sooner. 

Tuesday, October 9, 2012

My Quantum Mechanics Presentation to My School

For anyone who has read my posts here, or might be interested, here is a presentation I gave to my school last week about quantum mechanics. The first video is the presentation itself, and the second is the question-and-answer portion. (Also, I have another new entry below this one.)

Part 1:

Part 2: