[T]he sparse list of great homegrown American physicists makes two things clear. Firstly, that America is truly a land of immigrants; it’s only by including foreign-born physicists like Fermi, Bethe, Einstein, Chandrasekhar, Wigner, Yang and Ulam can the list of American physicists even start to compete with the European list. Secondly and even more importantly, the selection demonstrates that even in 2013, physics in America is a very young science compared to European physics.
Archive for the 'History' Category
Ciudad Blanca, or “The White City,” has been a legend since the days of the conquistadors, who believed the Mosquitia rain forests hid a metropolis full of gold and searched for it in the 1500s. Throughout the 1900s, archaeologists documented mounds and other signs of ancient civilization in the Mosquitias region, but the shining golden city of legend has yet to make an appearance.
“We use lidar to pinpoint where human structures are by looking for linear shapes and rectangles,” Colorado State University research Stephen Leisz, who uses lidar in Mexico, said in a statement. “Nature doesn’t work in straight lines.”
How Bing and his influence in the recording industry helped to enable modern technology.
Bonus commentary on how the new “crooning” was a bad influence on the young. Nothing ever changes.
One thing that I don’t quite get is this:
a laser beam naturally loses its intensity with distance
If they mean that it spreads out, then it depends on where the beam is focused. Using a beam focused on the moon, (or at twice that distance so the return beam was still converging) would probably be hard, and definitely be an incredibly silly way to do the experiment, since a small beam means you’d have to know precisely where the target was. Using a beam that was expanding (unless you have a laser that has a kilometer-scale beam output) is the right way to do it, so you’re forced by expediency into using an expanding beam with it’s decreasing intensity, but that’s not the same as saying it’s inherent to the laser.
If the claim is something else, then I don’t get it at all.
Cool little bit of optics here. Scattered light gets partially polarized, depending on the angle, and will be maximally polarized at 90º from the source. Of course, light can scatter more than once, so this will not result in perfect polarization from the atmosphere.
The researchers said such sunstones could have helped the Vikings in their navigation from Norway to America before the discovery of the magnetic compass in Europe.
They would have relied upon the sun’s piercing rays reflected through a piece of the calcite. The trick is that light coming from 90 degrees opposite the sun will be polarised so even when the sun is below the horizon it is possible to tell where it is.
They used the double refraction of calcite to pinpoint the sun by rotating the crystals until both sides of the double image are of equal intensity.
Here’s a view of the sky at roughly 90º from the sun, looking through a linear polarizer at two orientations — one that blocks the most amount of light and one the blocks the least. You can tell the light is definitely polarized.
It was essentially a criminal justice Dewey Decimal System, the first step in taking police out of the dark ages. Before Bertillion standardized measurements, police just had a jumble of descriptions and photographs with no way to organize them so they’d almost never be able to cross reference existing records when people were arrested.
Fingerprinting isn’t the only technology difference in criminal investigation, of course. Much of forensic pathology dates from after this time.
If you’re lucky, you may see what no one has seen before—no one has ever seen the drop fall.
John Mainstone, a physics professor at the University of Queensland and the experiment’s current custodian, missed the last two drops by pure bad luck. Awaiting the eighth drip from a business trip, Mainstone secured a video surveillance system to trail the elusive drop. Alas, the video feed failed precisely during the fall of the eighth pitch-drop.
Short video and an excerpt from his report at the link.
Clear thought, clear writing. Feynman was perhaps the most efficient mechanism ever conceived for consuming complexity and pumping out simplicity.
Amen to that, though we have some good ones today, too.
One of the finest achievements of European furniture making, this cabinet is the most important product from Abraham (1711–1793) and David Roentgen’s (1743–1807) workshop. A writing cabinet crowned with a chiming clock, it features finely designed marquetry panels and elaborate mechanisms that allow for doors and drawers to be opened automatically at the touch of a button. Owned by King Frederick William II, the Berlin cabinet is uniquely remarkable for its ornate decoration, mechanical complexity, and sheer size.
Insert your own joke about x-rays here.
Imagine the scenario: you’re a security officer working at Los Alamos. You know that spheres are weapon parts. You walk into a technical area, and you see spheres all around! Is that an ashtray, or it is a model of a plutonium pit? Anxiety mounts — does the ashtray go into a safe at the end of the day, or does it stay out on the desk? (Has someone been tapping their cigarettes out into the pit model?)
All of this anxiety can be gone — gone! — by simply banning all non-nuclear spheres! That way you can effectively treat all spheres as sensitive shapes.
I find this to be an interesting problem — simplifying the task so that someone without the technical skills can make a determination about security. It’s frustrating from the vantage point of the scientist, especially because secrecy tends to run counter to our desire to share our work (an important step in advancing an idea) and also because of the observation about secrecy being contagious, like a disease.
I encountered this when I was in the navy. We had some relatively low-level classified material, from a technical standpoint, and all of it was stamped in red ink and stored in red folders. Security — comprised mostly of students-in-waiting, led by a few permanent staff, only had to have a “see red” mentality, rather than any training on whether a sheet of paper was a set of classified specs or a shopping list. I doubt at Los Alamos that the low-level guards worried about whether spheres were research parts — they had just been told that all spheres were a violation.
Look at the reverse, though. We try and classify things ourselves, and that can have a bad end when it comes to security. Take the incidents a few years ago in Boston involving flashy and/or colored lights. The “bomb” finders caused panic, simply because they had a mental image that objects with flashy lights are what bombs look like.
We’re at that time of year where people publish lists of top stories of the year, but as many crazy people will be happy to remind you, this Friday marks the end of another calendrical period, in the Mayan calendar.
[H]ere are the Top Ten Physics Breakthroughs of Baktun 13