Category Archives: Physics

Plutonium and an Announcement

Plutonium is element 94 and as such it has 94 protons in its nucleus. There are twenty known isotopes of plutonium with half-lifes ranging from 14 years (Pu-241) to 80 million years (Pu-244); there are no stable isotopes of plutonium, so it is only found naturally in trace amounts and most plutonium in use was created by human activity. The most obvious use of plutonium is in nuclear weapons, and the production of Pu-239 has made it the most abundant of the plutonium isotopes. The atomic bomb “Fat Man”, which was dropped on Nagasaki in 1945 used 6.2kg of plutonium, and 1-4kg of plutonium is considered to be all that is needed to build a well-designed nuclear device. Nuclear fuel is also a viable use of plutonium, the space probes Cassini, Voyager and New Horizons all use a plutonium, probably Pu-238, fuel source. Finally, if you ever have the opportunity to eat plutonium, don’t. Particulate plutonium can enter the lungs, where it decays and could cause radiation poisoning or cancer. Besides, plutonium tastes like metal.

Now, I’m off school for the next couple of months, so expect more Apocrypha. I don’t plan on setting up a formal schedule right now, but perhaps in the future I will. Anyway, have a great summer (or winter for you southern hemisphere people)

-kogan56

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Cherenkov Radiation (or the Photonic Boom)

I’m assuming many of you will know what a sonic boom is, if you travel fast enough through a medium sound waves will compress in front of you and produce a sonic boom. Of course, this only happens if you are traveling at greater than the speed of sound in a given medium. Cherenkov Radiation can be described as the light equivalent of the sonic boom. So here’s (a simplified version of) what happens. Nothing can travel at speeds greater than c, the speed of light in a vacuum, but light in a medium will travel slower than c and in that sense a particle could travel faster than light through that medium, and when a charged particle travels through a medium at a speed greater than light travels through that medium it excites nearby molecules, which in turn emit light. Doing this requires lots of energy, which is why it’s commonly seen in the cooling tanks of nuclear reactors.

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Speeding and Blue Shift

Okay, so I’m assuming speeding on roadways is illegal in most countries, and that driving through a red light is also illegal. Okay? Okay. Let’s talk about blue shift. Blue shift is an application of the Doppler effect to light. Basically, if you travel in the direction opposite a wave, the apparent frequency of said wave increases, and the opposite is true if you travel in the same direction as the wave, the apparent frequency decreases. Since blue has a high frequency and red has a low frequency (as far as light goes) light is blue shifted when moving toward the light source. So now that that’s taken care of, how fast would you need to be going to see a red light at an intersecti0n as a green light. Using the speed of light, a frequency for red light (4.4*10^14 Hz), a frequency for green light (6*10^14 Hz), and Wolfram|Alpha, we get a speed of about 3/10 of the speed of light. That’s fast.

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Ultimate Hot

Let’s start this fun fact with something else, black-body radiation. Black-body radiation is light given off by any object with a temperature of more than 0K, or absolute zero (very,very cold). Basically, everything glows, but not necessarily in visible light. Humans glow in infrared, the sun’s surface glows in the visible to ultraviolet range, and the sun’s core glows in the x-ray to gamma radiation range. We can extrapolate on these observations (I’ll be making extensive reference to Wien’s displacement law) to find out when something is absolutely hot, that is, when things are so hot they make no sense in our current models of the physical universe. This point occurs when the black-body radiation that is given off by an object with a temperature around 10^32 Kelvin. For the rest of you out there, that’s so hot your molecules will break apart, the atoms in them will break apart, the nuclei in those will break apart, the protons and neutrons in those will break apart, and that’s it. Physics can predict nothing beyond what is now know as absolute hot.

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Double Post: Exponential growth and “free energy”

Okay, since I missed yesterday, here’s two fun facts. Exponential growth and “free energy”

First, exponential growth. Say you have a piece of paper a millimeter thick (yes, I realize paper isn’t normally that thick, but the point is the same). If you fold the paper in half (assuming there’s no air in the fold) you will have a piece of paper two millimeters thick. Folding the paper again will give 4 millimeters, then 8, then 16, and so on. This process, the increase by a certain ratio over each fixed period of time, is exponential growth, but only if the ratio is greater than 1 (in this case, the ratio is 2). Now let’s take the area of the same paper starting with, say, 10 square centimeters. After one fold the area of the paper is now 5 square centimeters, after another it’s 2.5, then 1.25, and so on again. This process, which is the same as with thickness, but with a ratio between 0 and 1 (in this case 1/2) is exponential decay.

Finally, free energy. That’s be great right? But that’s where we get to free energy suppression. The governments, oil and gas companies, and scientific communities of the world don’t want you to know that there are machines that can harvest energy from perpetual motion and zero-point energy. But those of you versed in physics will know that there is no such thing as a “perpetual motion machine” and that zero-point energy cannot be “harvested”. But that’s where suppression comes in. If you say those things then either you have been manipulated by the scientific establishment into believing them, or you are actively participating in the cover-up. One popular free energy concept is the “motionless electromagnetic generator” which harnesses vacuum energy to provide power without any input into the generator itself. Its inventor, Dr. Thomas E. Bearden, stated in 2001 that it would be in production in a year. I haven’t seen any motionless electromagnetic generator, likely because, even in 2012, ten years behind schedule, no working MEG has been built. It also doesn’t help that “Dr.” Bearden holds a Ph.D., which he bought, from one Trinity College and University, which has “no building, campus, faculty, or president, and run from a post office box in Sioux Falls, South Dakota”
PS: I’d like to note, although it may be obvious, that I in no way endorse the “free energy suppression” conspiracy theory because that’s exactly what it is, a pseudo-scientific conspiracy theory.

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Destroying the Earth

Don’t worry, the Earth isn’t going anywhere. But there are a few things you can learn from trying to destroy the Earth. First of all you need to know the Earth’s radius, which varies, depending on how you measure it, but never by more than about 45 km. This deviation is considerable (.7%), but let’s use the mean radius of 6,371km Actually, if the Earth were the size of a pool ball (aka billiard ball), the Earth would be smoother. You also need to know the Earth’s mass. That’s easier, but 18-36 METRIC TONS of material are added to the Earth EVERY DAY. But on the scale we’re dealing with, 20-40 tons is negligible. That’s because the Earth weighs around 6*10^21 metric tons. Now, using the gravitational binding energy formula (U=3Gm^2/5r, m is mass, r is radius, U is the gravitational binding energy, or energy needed to destroy the Earth, and G is the universal gravitational constant), we can figure out the minimum amount of energy needed to destroy the Earth. After running the numbers through the Wolfram|Alpha program, we get a value of about 2*10^32 joules. To put that in perspective, the largest nuclear bomb ever detonated was the Tsar Bomba, with a yield of about 2*10^17 joules. You would need to give one MILLION Tsar Bombas to EVERY person on the planet (given that there are around 7 billion people alive right now) in order to generate enough energy to destroy the planet. Have fun with that.

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The Mpemba Effect

Although such famous people as Aristotle, Sir Francis Bacon and René Descartes described the Mpemba Effect, it is named after Erasto Mpemba, who noticed that, at equal quantities, boiling water will freeze faster than water at room temperature. Although it’s not clear whether or not freezing refers to the formation of visible ice or complete solidification, or what other conditions there were, so the effect remains largely anecdotal. Finally, possible explanations for the phenomenon include the insulating effects of frost, evaporation of the warmer water and different dissolved gasses in the two water samples.

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