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Catching Elephant is a theme by Andy Taylor
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the most romantic thing I found in science so far
(Nov. 28, 2011)
Physicists from the University of Stuttgart show the first experimental proof of a molecule consisting of two identical atoms that exhibits a permanent electric dipole moment. This observation contradicts the classical opinion described in many physics and chemistry textbooks.
A dipolar molecule forms as a result of a charge separation between the negative charged electron cloud and the positive core, creating a permanent electric dipole moment. Usually this charge separation originates in different attraction of the cores of different elements onto the negative charged electrons. Due to symmetry reasons homonuclear molecules, consisting only of atoms of the same element, therefore could not possess dipole moments.
However, the dipolar molecules that were discovered by the group of Prof. Tilman Pfau at the 5th Institute of Physics at the University of Stuttgart do consist of two atoms of the element rubidium.
I really like this gif of the relationship between torque, force, linear momentum, and angular momentum.
r = radius, F = force, p = linear momentum, L= angular momentum, τ = torque.
It really explains a lot.
(Source: Wikipedia)
Does anyone know where I can find some good physics videos on rotational motion? And one which goes through examples, not just derive the equations. And which explains in detail the methods?
A little overwhelmed, last night I decided to skip ahead in the book and read about relativity. And I realized that although there are bits and pieces of physics that stress me out from time to time, not knowing is part of the process.
One can’t expect to understand everything immediately, and if they do they are fooling themselves. I want to be challenged, and I want to understand things. Reading that section of the book was absolutely fascinating and brought me to perspective. It made me understand that I am going to have to work hard, and I’m going to have to accept that sometimes this field will be hard. But to understand the world around me, and the universe around me, is entirely worth it in the end. And now I am a little excited and in anticipation of what we will learn next in the class.
Can I ask someone a physics question?
Let me know if I can ask you.
It’s a lot to ask, but would anyone be willing to answer physics questions I might have? Not necessarily today, but in general? If you understand calculus related physics questions.
If you have a skype that would be even better.
This man is really good at explaining Kinematics.
Warp Drive May Be More Feasible Than Thought, Scientists Say
A warp drive to achieve faster-than-light travel — a concept popularized in television’s Star Trek — may not be as unrealistic as once thought, scientists say.
A warp drive would manipulate space-time itself to move a starship, taking advantage of a loophole in the laws of physics that prevent anything from moving faster than light. A concept for a real-life warp drive was suggested in 1994 by Mexican physicist Miguel Alcubierre; however, subsequent calculations found that such a device would require prohibitive amounts of energy.
Now physicists say that adjustments can be made to the proposed warp drive that would enable it to run on significantly less energy, potentially bringing the idea back from the realm of science fiction into science.
“There is hope,” Harold “Sonny” White of NASA’s Johnson Space Center said here Friday (Sept. 14) at the 100 Year Starship Symposium, a meeting to discuss the challenges of interstellar spaceflight.
Warping space-time
An Alcubierre warp drive would involve a football-shape spacecraft attached to a large ring encircling it. This ring, potentially made of exotic matter, would cause space-time to warp around the starship, creating a region of contracted space in front of it and expanded space behind.
Meanwhile, the starship itself would stay inside a bubble of flat space-time that wasn’t being warped at all.
“Everything within space is restricted by the speed of light,” explained Richard Obousy, president of Icarus Interstellar, a non-profit group of scientists and engineers devoted to pursuing interstellar spaceflight. “But the really cool thing is space-time, the fabric of space, is not limited by the speed of light.”
With this concept, the spacecraft would be able to achieve an effective speed of about 10 times the speed of light, all without breaking the cosmic speed limit.
The only problem is, previous studies estimated the warp drive would require a minimum amount of energy about equal to the mass-energy of the planet Jupiter.
But recently White calculated what would happen if the shape of the ring encircling the spacecraft was adjusted into more of a rounded donut, as opposed to a flat ring. He found in that case, the warp drive could be powered by a mass about the size of a spacecraft like the Voyager 1 probe NASA launched in 1977.
Furthermore, if the intensity of the space warps can be oscillated over time, the energy required is reduced even more, White found.
“The findings I presented today change it from impractical to plausible and worth further investigation,” White told SPACE.com. “The additional energy reduction realized by oscillating the bubble intensity is an interesting conjecture that we will enjoy looking at in the lab.”
Art by { dvdp }
THE PHYSICS OF SPIRALS?
Perhaps someone with more experience in math & physics can give some insight about this:
I’ve subscribed to a weekly newsletter from { Kurzweil AI } (Many of you might find it interesting; it covers futurism, technology, science, etc.) Recently, there were two consecutive articles about spiral shapes that I found curious:
{Pasta-shaped radio waves beamed across Venice }
A group of Italian and Swedish researchers may have solved the problem of radio congestion by cleverly twisting radio waves into the shape of fusilli pasta, allowing a potentially infinite number of channels to be broadcast and received.
& { Scientists twist light to send data at more than 2 terabits per second }
A multinational team led by USC with researchers in the U.S., China, Pakistan, and Israel has developed a system of transmitting data using twisted beams of light at ultra-high speeds — up to 2.56 terabits per second.
Broadband cable supports up to about 30 megabits per second. The twisted-light system transmits about 85,000 times more data per second.
Is there something inherent to spiral shapes that allows them to hold more “information”? (I’m using the word info. in a general way, like if we think of the universe as a system of variously configured “bits” of info.) Is the relationship — in terms of information — between these technologies and natural constructs like DNA and galaxies more than an aesthetic correlation? If it’s true that spirals “hold more”, why is this?
P.S.
I’ve also asked this question at { Udacity }, if any of you are enrolled in Intro to Physics. I’ll re-post answers here if anyone answers there, and vice versa.
Time Stands Still
Tonight’s “leap second” and why the Earth sucks at keeping time
If you stand very still tonight, holding your breath in the still of midnight darkness, you’ll hear the sound of all the clocks in the world pausing for one second. Actually, you probably won’t hear anything, but you should know that today will be one second longer than a normal day. Why?
When trains began to make long-distance travel possible, with schedules dependable down to the minute, there was a worldwide demand for standardized time. So we got Greenwich Mean Time, which defined the measure of a day as the average time of a single rotation of the Earth from the perspective of one Englishman staring up at the sky in Greenwich. In 1820, this just so happened to be 86,400 seconds, or 24 hours.
The problem is that the Earth’s rotation is slowing down, and a “solar day” isn’t exactly 86,400 seconds anymore. The Earth doesn’t care about our time system one bit, apparently.
How does that work? The Moon pulls on the Earth due to its own gravity. When that’s combined with the natural gravity of the Earth, we get two “high-tide” bulges on opposite sides of our planet. But the bulges don’t line up perfectly with the equator, and the Moon actually pulls on the ocean enough to create a tiny amount of friction. That friction is slowing our rotation by about 0.002 seconds per day per century. Eventually the Earth and Moon will be “tidally locked” and each will have a constant face to the other (like the Moon does to Earth today). Phil Plait explains this all pretty well here. Moreover, earthquakes and all sorts of other stuff mean that this “slowing” business is also irregular.
Earth sucks as a timepiece.
Since the 1970’s, our “official time” has been kept by atomic clocks, accurate to one second every 250 million years. We actually changed the official definition of a second to be based on atoms instead of 1/86,400th of a day. But many traditional clocks, not to mention our bodies, are basing their day on day/night averages, and the atomic clocks are basing it on cesium atoms (far more accurately). The day/night clocks are lagging behind! So on a regular basis, the Time Lords of Earth let the atomic clock time pause for one second to bring them closer to sync. That’s a leap second.
If we didn’t do this, and just let the clocks go their separate ways, we might cause serious problems to systems like GPS software that depend on super-super-accurate time-keeping.
So tonight, the official clocks will show 23:59:60 before rolling over to tomorrow, and everything is in its right place. Don’t worry if you forget to sync your watch. You’ll just be a second early everywhere tomorrow.
I’ll be spending my extra second sleeping.
Utterly mesmerizing: Water droplets colliding at 5,000 frames per second, a fine addition to this collection of mesmerizing footage of everyday things in ultra-slow-motion.
Ahh, soothing fluid dynamics.
Atom Crash Produces Hottest Man-Made Temperature Ever
An atom-smasher called the Relativistic Heavy Ion Collider (RHIC) has just snagged a Guinness World Record for reaching the hottest man-made temperature ever—250,000 times hotter than the center of the sun.
Image credit: Panos Karanpanagiotis/Shutterstock
The Last Nail in the Faster-Than-Light Neutrino Coffin
Rest easy, folks. Einstein’s legacy and theories are safe. CERN released a statement today reporting that several follow-up experiments have made it clear that last year’s claims of neutrinos being clocked at faster than the speed of light were incorrect (my collected posts on the whole saga).
It wasn’t relativity, or strange physics, or the movement of the Earth’s crust that led to the odd result, either. It was a loose cable.
I’m not sure what the fallout will be for people’s trust in science, or science news, or boys crying wolf. People paid attention to something very exciting, and many of us learned something new about physics that we never would have. But part of it was a result of people overblowing overblown overblownalities. A trade-off of integrity and education. I tend to agree with CERN’s Sergio Bertolucci:
The story captured the public imagination, and has given people the opportunity to see the scientific method in action – an unexpected result was put up for scrutiny, thoroughly investigated and resolved in part thanks to collaboration between normally competing experiments. That’s how science moves forward.
And move forward we will. Just not faster than the speed of light.
