On what would have been his 78th birthday, here’s a selection of Sagan-inspired GIFs to honor the late sage of science and science popularization. The garden of our mind would not grow as rich if it weren’t for people like Carl, and without him, many people like me certainly wouldn’t be talking science at you all the time. He’s my greatest inspiration as a teacher, and I don’t think I’m the only one.
What’s that? You want more than just some GIFs? Okay! Click here or here to find pretty much all of my Carl Sagan posts, ever. My apologies to your productivity.
With a neutral charge and nearly zero mass, neutrinos are the shadiest of particles, rarely interacting with ordinary matter and slipping through our bodies, buildings and the Earth at a rate of trillions per second.
First predicted in 1930 by Wolfgang Pauli, who won a Nobel prize for this work in 1945, they are produced in various nuclear reactions: fusion, which powers the sun; fission, harnessed by humans to make weapons and energy; and during natural radioactive decay inside the Earth.
If they are so stealthy, how do we know they are there at all?
Most commonly, experiments use large pools of water or oil. When neutrinos interact with electrons or nuclei of those water or oil molecules, they give off a flash of light that sensors can detect.
Where are these experiments found?
These days, a lot of expense and extreme engineering go into detectors that are sunk into the ground to shield them from extraneous particles that might interfere with them. For instance, OPERA, which detected the apparently faster-than-light neutrinos beamed from CERN, lies inside the Gran Sasso mountain in Italy. This works because neutrinos shoot straight through such shields.
Their stealth belies their potential importance. Take extra dimensions. Most particles come in two varieties: ones that spin clockwise and ones that spin anticlockwise. Neutrinos are the only particles that seem to just spin anticlockwise. Some theorists say this is evidence for extra dimensions, which could host the “missing”, right-handed neutrinos.
Unseen right-handed neutrinos may also account for mysterious dark matter. This is thought to make up 80 per cent of all matter in the universe and to stop galaxies from flying apart. The idea is that right-handed neutrinos might be much heavier than left-handed ones and so could provide the requisite gravity.
Say hello to the Martin Jetpack. This bad boy, when it’s officially released in 2012, will be able to reach heights of up to 5000 feet. Power comes by way of a two-stroke custom gas engine that is used to spin a pair of ducted fans. That’s where you get your thrust and then steering is done by a an electronic, fly-by-wire system. I think that’s better than the cable and pulley steering that we had seen previously. The jetpack is classified as ultralight under FAA standards, so you won’t need a license either. It is limited to 30 minutes of flight and a max speed of 63mph, though.
The double-slit experiment, or the Young’s experiment, illustrates wave-particle duality, the principle that matter and energy display characteristics of both waves and particles.
To perform the experiment, shine a light source toward a thin plate with two parallel slits. The light should shine through the slits onto a screen behind the plate.
The light waves from the two slits will interfere, producing bands of light and dark on the screen, demonstrating the wave nature of light. The light will also be absorbed at the screen, however, as though it were discrete particles. Thus, wave-particle duality!