glycinedust-blog - Tumblr blog

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I've decided to move the blog to a new, completely different account, so here is the link above. So my dear followers should all migrate, unfollow glycinedust and follow antitau. :)

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Ohmigosh. This is so useful for my Chem notes. Thank you to whoever posted this.

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How to Use a Multimeter: Measuring Current

Physics teacher Ronan McDonald demonstrates how to use a multimeter to measure current.

I love multimeters! Such useful things when it comes to physics experiments!

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“The camera lucida (light chamber) transforms sound waves directly into light emissions. In a transparent chamber filled with a gas-enriched fluid, several ultrasound transformers produce a constantly changing sonochemical environment. The ultrasound waves’ propagation through the fluid brings about the formation of tiny bubbles whose implosions achieve temperatures that are as hot as the surface of the sun. As a result, sound waves in the form of light are emitted. Evelina Domnitch, Dmitry Gelfand”

Aside: I met Dmitry Gelfand at the Perimeter Institute for a workshop yesterday. He should be the Fresh Photons mascot. So amazing.

Wow. As unprofessional as this sounds, they look like hair! O_o

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Those weird faster-than-light neutrinos that CERN thought they saw last month may have just gotten slowed down to a speed that’ll keep them from completely destroying physics as we know it. In an ironic twist, the very theory that these neutrinos would have disproved may explain exactly what happened.

Back in September, physicists ran an experiment where they sent bunches of neutrinos from Switzerland to Italy and measured how long the particles took to make the trip. Over 15,000 experiments, the neutrinos consistently arrived about 60 nanoseconds early, which means 60 nanoseconds faster than the speed of light. Einstein’s special theory of relativity says this should be impossible: nothing can travel faster than light.

The fact that the experiment gave the same result so many times suggested that one of two things was true: either the neutrinos really were speeding past light itself and heralding a new era of physics, or there was some fundamental flaw with the experiment, which was much more likely. It’s now looking as though the faster-than-light result was a fundamental flaw, and appropriately enough, it’s a flaw that actually helps to reinforce relativity rather than question it.

The Experiment

Here’s the deal: neutrinos move very very fast (at or close to light speed, at least), and the distance that they traveled in this experiment was (to a neutrino) not that far, only 450 miles. This means that in order to figure out exactly how long it takes a given neutrino to make the trip, you need to know two things very, very precisely: the distance between the two points, and the time the neutrino leaves the first point (the source) and arrives at the second point (the detector).

In the original experiment, the CERN researchers used GPS to make both the distance measurement and the time measurement. They figured out the distance down to about 20 centimeters, which is certainly possible with GPS, and since GPS satellites all broadcast an extremely accurate time signal by radio, they were also used as a way to sync the clocks that measured the neutrino’s travel time. The CERN team had to account for a lot of different variables to do this, like the time that it takes for the clock signal to make it from the satellite in orbit to the ground, but they may have forgotten one critical thing: relativity.

It’s All Relative

Relativity is really, really weird. It says that things like distance and time can change depending on how you look at them, especially if you’re moving very fast relative to something else. In the case of the neutrino experiment, we’ve got two things to think about: the detectors on the ground that measure where and when the neutrinos depart and arrive, and the GPS satellites up in space that we’re using as a basis for these measurements. Since the satellites are orbiting the Earth and moving way faster than the detectors, we say that they’re in a different “reference frame,” which just means that the motion of the satellites is significantly different than the motion of the Earth.

Part of the deal with relativity is that neither of these reference frames are the “correct” one. From our perspective here on Earth, the satellites are whizzing around in orbit at about 9,000 miles per hour. But the perspective of the satellites, the Earth is whizzing around just as fast, and the difference in velocities between these two reference frames is large enough that some strange things start to happen.

A Satellite’s Perspective

To understand how relativity altered the neutrino experiment, it helps to pretend that we’re hanging out on one of those GPS satellites, watching the Earth go by underneath you. Remember, from the reference frame of someone on the satellite, we’re not moving, but the Earth is. As the neutrino experiment goes by, we start timing one of the neutrinos as it exits the source in Switzerland. Meanwhile, the detector in Italy is moving just as fast as the rest of the Earth, and from our perspective it’s moving towards the source. This means that the neutrino will have a slightly shorter distance to travel than it would if the experiment were stationary. We stop timing the neutrino when it arrives in Italy, and calculate that it moves at a speed that’s comfortably below the speed of light.

“That makes sense,” we say, and send the start time and the stop time down to our colleagues on Earth, who take one look at our numbers and freak out. “That doesn’t make sense,” they say. “There’s no way that a neutrino could have covered the distance we’re measuring down here in the time you measured up there without going faster than light!”

And they’re totally, 100% correct, because the distance that the neutrinos had to travel in their reference frame is longer than the distance that the neutrinos had to travel in our reference frame, because in our reference frame, the detector was moving towards the source. In other words, the GPS clock is bang on the nose, but since the clock is in a different reference frame, you have to compensate for relativity if you’re going to use it to make highly accurate measurements.

Not So Fast

Researchers at the University of Groningen in the Netherlands went and crunched the numbers on how much relativity should have effected the experiment, and found that the correct compensation should be about 32 additional nanoseconds on each end, which neatly takes care of the 60 nanosecond speed boost that the neutrinos originally seemed to have. This all has to be peer-reviewed and confirmed, of course, but at least for now, it seems like the theory of relativity is not only safe, but confirmed once again.

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The Pioneer Plaque

The original idea, that the Pioneer spacecraft should carry a message from humankind, was first mentioned by Eric Burgess when he visited the Jet Propulsion Laboratory in Pasadena, California during the Mariner 9 mission. He approached Carl Sagan, who had lectured about communication with extraterrestrial intelligences at a conference in Crimea.

Sagan was enthusiastic about the idea of sending a message with the Pioneer spacecraft. NASA agreed to the plan and gave him three weeks to prepare a message. Together with Frank Drake he designed the plaque, and the artwork was prepared by Sagan’s then-wife Linda Salzman Sagan.

[Definitely click through to read everything this seemingly simple image is communicating. Absolutely astounding.

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On one of my favorite elements: Mercury

Mercury has quite a bad reputation, sure it’s incredibly toxic, but that’s only because it’s too awesome for you to handle. Aside from the chemistry behind it, mercury also has a fascinating ironic history as a health tonic. Interestingly enough only 0.01% is actually absorbed through the gastrointestinal tract while 80% most moves through the mucous membranes of the mouth and nasal cavity. While the chemical symbol Hg comes from the word hydrargyrum which means “Silver water” in Greek. The common name for Mercury comes from the God due to it’s reflectiveness and relatively rapid movement. The coolest thing about mercury has to be fact that along with bromine it is one of only two elements that exist in the liquid state at room temperature. The secret behind this is due to the distribution of electrons in orbitals surrounding the atom. As a gross oversimplification there are simply no electrons to be shared among neighboring mercury atoms to form metallic bonds. Most metals on the other hand share electrons with neighboring atoms in order to have the most energetically stable form, while mercury has enough electrons to be stable on it’s own, somewhat reminiscent of the noble gases. Aside from this mercury is not entirely inert, but can also form special alloys known as amalgams with other metals, some of which are even commonly used in dentistry as fillings. Mercury also has the bizarre effect of seeming to dissolve aluminum. In this process mercury reacts with aluminum to form an amalgam, the aluminum then oxidizes to form aluminum oxide and the mercury “dissolves” more aluminum to replace the aluminum lost as an oxide.

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“Scientists are explorers. Philosophers are tourists.”

Richard Feynman, American physicist (1918-1988),  in 1985, cited in G. Laurence Nickard, Phenomenal surfaces and noumenal depths: Philosophy and quantum theory, ProQuest, 2006, p. 5. (via amiquote)

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You can know the name of a bird in all the languages of the world, but when you’re finished, you’ll know absolutely nothing whatever about the bird… So let’s look at the bird and see what it’s doing — that’s what counts. I learned very early the difference between knowing the name of something and knowing something.

-Richard Feynman

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ohmysagan:

Has Science Found the First “White” Hole?

A white hole is a theoretical beastie that exists as a set of equations that were a by-product of Einstein’s theory of relativity. It is basically a black hole in reverse. If a black hole is an object from which nothing can escape, then a white hole is an object into which nothing can enter—it can only radiate energy and matter.

Read The Article

:O

I was thinking... Leaving out the consideration that basically everything about quantum mechanics is nothing but theories and nothing can quite be proven empirically, isn't it funny how really, a white hole should not naturally exist? Unless it's pure luck. The fact that we called the black holes "black holes" happened randomly and only if we consider language and think of opposites can we imagine a white hole. (Black is opposite to white.) So white holes shouldn't be considered to exist just because white is opposite to black. Or if something opposite to a black hole exists, it certainly shouldn't be called a "white hole". If instead of pulling things into itself, it pushes things out, it shouldn't even be called a hole. Unless it is literally a black hole inside out, so on the other side, in some other universe, it is a "black hole", and everything is pulled not into singularity but into another universe. In which case the concept of the "black hole" changes completely.

I think scientists tend to have trouble naming things.

Just saying. :P

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I warned you not everything I post will be about physics. ;)

Here's a really interesting proposal on how to help our environment by allowing our dead bodies not to be cremated or to just be allowed to decompose, but to be eaten up by mushrooms that will not allow the toxins in our bodies to go back into the atmosphere and will give nutrients to our planet. Would you let your body be eaten by mushrooms after you die? Some people would.

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Can somebody please get me this book for Christmas? Anyone? Pleeaase? I'm serious here.

It's only ten pounds.

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Dr. Quantum - Double-Slit Experiment

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One day, all of the world’s famous physicists decided to get together for a party (ok, there were some non-physicists too who crashed the party). Fortunately, the doorman was a grad student, and able to observe some of the guests… 

Everyone gravitated toward Newton, but he just kept moving around at a constant velocity and showed no reaction.

Einstein thought it was a relatively good time.

Coulomb got a real charge out of the whole thing.

Cauchy, being the mathematician, still managed to integrate well with everyone.

Thompson enjoyed the plum pudding.

Pauli came late, but was mostly excluded from things, so he split.

Pascal was under too much pressure to enjoy himself.

Ohm spent most of the time resisting Ampere’s opinions on current events.

Hamilton went to the buffet tables exactly once.

Volta thought the social had a lot of potential.

Hilbert was pretty spaced out for most of it.

Heisenberg may or may not have been there.

Feynman got from the door to the buffet table by taking every possible path

The Curies were there and just glowed the whole time.

van der Waals forced himeself to mingle.

Wien radiated a colourful personality.

Millikan dropped his Italian oil dressing.

de Broglie mostly just stood in the corner and waved.

Hollerith liked the hole idea.

Stefan and Boltzman got into some hot debates.

Everyone was attracted to Tesla’s magnetic personality.

Compton was a little scatter-brained at times.

Bohr ate too much and got atomic ache.

Watt turned out to be a powerful speaker.

Hertz went back to the buffet table several times a minute.

Faraday had quite a capacity for food.

Oppenheimer got bombed.

The microwave started radiating in the background when Penzias and Wilson showed up.

After one bite Chandrasekhar reached his limit.

Gamow left the party early with a big bang while Hoyle stayed late in a steady state.

For Schrodinger this was more a wave function rather than a social function.

Skorucak wanted to put everybody on his web site.

Erdos was sad no epsilons were invited.

Born thought the probability of enjoying himself was pretty high.

Instead of coming through the front door Josephson tunnelled through.

Groucho refused to attend any party that would invite him in the first place.

Niccolò Tartaglia kept stammering throughout the evening.

Pauling wanted to bond with everyone.

Keynes was keen to question the marginal utility of this party.

Shakespeare could not decide whether to be or not to be at the party.

John Forbes Nash wanted to play a n-person zero sum game.

Pavlov brought his dog; which promptly chased after Schrodinger’s cat.

Zeno of Elea came with two friends - Achilles and the tortoise.

Bill Gates came to install windows.

Bertrand Russell kept wondering if the cook only cooks for the guests, who cooks for the cook?

Witten bought a present all tied up with superstrings.

The food was beautifully laid out by Mendeleyev on the periodic table.

Riemann hypothesised about who would arrive next; to which Newton retorted, ’ hypotheses non fingo.’

Chadwick was handing out neutrons free of charge.

Everyone was amazed at Bell’s inequality.

Watson and Crick danced the Double Helix.

While Fermat sang, ‘Save the Last Theorem for me.’

Maxwell’s demon argued with Dawkin’s friend, the selfish Gene.

Russell and Whitehead insisted on checking the bill for completeness and consistency. Godel said it was incomplete and it can never be proved otherwise.

Epimenides the Cretan announced that only non-Cretans spoke the truth.

Rontgen saw through everybody.

Descartes cogitated, ‘I think I am drunk. Therefore I am at the party.’