Posts from the ‘Interesting’ Category

quantumaniac:

First Practical Maser (Microwave Laser) Built

Using spare chemicals, a laser bought on eBay and angst from a late-night argument, physicists have got the world’s first room-temperature microwave laser working. The achievement comes nearly 60 years after the first clunky versions of such devices were built, and could revolutionize communication and space exploration. The work is published this week in Nature.

Before there were lasers, there were microwave lasers, or masers. First conceived in the Soviet Union and the United States during the 1950s, early maser machines were the size of a chest of drawers. They produced only a few nanowatts of power, severely limiting their usefulness.

Because of this impediment, most in the field gave up on masers and moved on to lasers, which use the same principles of physics, but work with optical light instead of microwaves. Lasers are now used in applications ranging from eye surgery to CD players. The poor maser lived on in obscurity. It found only a few niche uses, such as boosting radio signals from distant spacecraft — including NASA’s Curiosity Mars rover. Those masers work only when cooled to less than ten degrees above absolute zero, and even then they are not nearly as powerful as lasers.

Pink power
But Mark Oxborrow, a physicist at the UK National Physical Laboratory in Teddington, wondered whether a crystal containing the organic molecule pentacene might offer a breakthrough. He came across a decade-old publication by Japaneseresearchers suggesting that when the electrons in pentacene are excited by a laser, they configure such that the molecule could work as a maser, possibly even at room temperature.

He borrowed some spare pentacene from a lab at Imperial, and cooked it with another organic molecule known as p-terphenyl. The result was a pink crystal a few centimeters long.

Next, the team needed a powerful laser. Oxborrow located an old medical laser on eBay and drove to a warehouse in north London to pick it up. But the researchers were filled with doubts — the whole thing seemed too easy. Oxborrow admits that he was skittish about the experiment. “For about three days, I could have done it, but I didn’t have the nerve to switch on that button,” he says.

The final impetus came from an argument with his wife. Whereas less well-behaved people might have wallowed in the pub, “I went to the lab as a bit of therapy”, says Oxborrow. “I said, ‘Oh well, what the hell, let’s just try it.” And it worked on the first go.

Excited state
The laser light excited the pentacene molecules to an energy level known as a metastable state. Then a microwave passing through the crystal triggered the molecules to relax, releasing a cascade of microwaves of the same wavelength.

It was the same principle as an optical laser. “The signal that came out of it was huge,” says Oxborrow, about a hundred million times as powerful as an existing maser. Alone in his lab, “I swore a lot and walked around the corridor about five times talking to myself”.

Left: New maser

Right: A Hydrogen Radio Frequency Discharge (early Maser)

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quantumaniac:

Happy Birthday NASA! 

Today, July 29th, marks the 54th anniversary of the passage of the National Aeronautics and Space Act – which established NASA. Since February 2006, NASA’s mission statement has been to ”pioneer the future in space exploration, scientific discovery and aeronautics research.” NASA replaced its predecessor, the National Advisory Committee for Aeronautics (NACA). The agency became operational on October 1, 1958.

quantumaniac:

How Much Does Fire Weigh? 

Question: Since fire is a plasma, and plasma is a state of matter, and matter is defined as anything that has mass, would that then mean that fire has mass and weight to it? If so, is there a way to measure its weight? How much space would, say, a pound of fire take up?

AnswerIt weighs more than nothing, but if you’re at the bottom of a pillar of fire, being crushed should be your second concern

Fires, putting aside details about plasma and chemicals or whatever, is just hot air.  For a given pressure the ideal gas law says that the density of a gas is inversely proportional to temperature, in Kelvin.  You can use this fact, the temperature and density of air (300°K 1.3 kg/m3), and the temperature of your average run-of-the-mill open flame (about 1300°K) to find the density of fire. For most “everyday” fires, the density of the gas in the flame will be about 1/4 the density of air.  So, since air (at sea level) weighs about 1.3 kg per cubic meter (1.3 grams per liter), fire weighs about 0.3 kg per cubic meter.

One pound of ordinary fire, here on Earth near sea level, would take up a cube about 1.2 meters to a side.  The reason that fires always flow upward is that its density is lower than air.  So, fire rises in air for the same reason that bubbles rise in water: it’s buoyant.  Enterprising individuals sometimes even take advantage of that fact.

If you were on a planet with no air at all, fire would fall to the ground instead of rise because, like all matter, it’s pulled by gravity.  Also, it would be hard to keep the fire going (what with there being no air).

Well that’s fascinating. Not sure if being crushed or burnt to death would be worse!

quantumaniac:

Isaac Newton Fun Facts
Isaac Newton (1642-1727) was without a doubt one of the most important scientists of all time, if not the most important. Here are some fun facts about ol’ Ike: 
  • Newton became a professor of mathematics at only 26.
  • Newton practiced Alchemy. 
  • Newton was elected as a member of parliment. His membership lasted only a year.
  • Newton earned the title of Warden of the Royal Mint.
  • Newton oversaw the recoinage of the whole country.
  • Newton was knighted because of his political activites.
  • He was named after his father who died three months before Isaac was born.
  • Isaac was born early. He was so small he could have put him in a quart jug.
  • Isaac’s father could hardly write his name.
  • Isaac was one of the worst in his class until a bully at school kicked him. Isaac challenged him to a fight even though he was smaller. He won. That wasn’t enough for him, he decided to be better than the bully at school as well.
  • Isaac liked to draw, his room was even colored on the ceilings and walls.
  • Newton was born on Christmas.

Posted a little bit ago, he is also Neil DeGrasse Tyson’s favorite scientist! Because who doesn’t like a guy who creates a whole new math just to prove he’s right?

quantumaniac:

Earth Will One Day See a Second Sun

Betelgeuse, a red supergiant star located in the Orion constellation, about 640 light-years away from Earth – is preparing to explode via a supernova. When it does, the Earth will have a front-row seat; in fact, the explosion will be so bright that Earth will seem to briefly have two suns in the sky. 

Betelgeuse is one of the brightest and largest stars in our immediate galactic neighborhood – if you dropped it in our Solar System, it would extend all the way out to Jupiter, leaving Earth completely engulfed. In stellar terms, it’s predicted to explode in the very near future. Of course, the conversion from stellar to human terms is pretty extreme, as Betelgeuse is predicted to explode anytime in the next million years.

But still, whether the explosion occurs in 2011 or 1002011 (give or take 640 years for the light to reach Earth), it’s going to make for one of the most unforgettable light shows in our planet’s history. For a few weeks, the supernova will be so bright that there will appear to be two stars in the sky, and night will be indistinguishable from day for much of that time. So don’t count on getting a lot of sleep when Betelgeuse explodes, because the only sensible thing for the world to do will be to throw a weeks-long global supernova party.

Physicist Brad Carter explains what Earth (and hopefully humanity) can look forward to:

“This is the final hurrah for the star. It goes bang, it explodes, it lights up – we’ll have incredible brightness for a brief period of time for a couple of weeks and then over the coming months it begins to fade and then eventually it will be very hard to see at all.”

Although there’ll be no missing the explosion, Carter points out that the vast majority of material shot out from the supernova will pass by Earth completely unnoticed:

“When a star goes bang, the first we will observe of it is a rain of tiny particles called neutrinos. They will flood through the Earth and bizarrely enough, even though the supernova we see visually will light up the night sky, 99 per cent of the energy in the supernova is released in these particles that will come through our bodies and through the Earth with absolutely no harm whatsoever.”

In any event, the Betelgeuse explosion will likely be the most dramatic supernova Earth ever witnesses – well, unless our Sun eventually explodes and destroys our planet, which would probably leave Betelgeuse the runner-up.

We should have a global supernova party every year anyway!