Archive | October, 2011

Oldest recorded supernova

31 Oct

This picture was recently released by NASA. It was made by combining data from 4 different space telescopes at different wavelengths. RCW 86 is the oldest documented example of a supernova, and was observed by the Chinese in 185 A.D. They called it a “guest star” and documented that it stayed in the sky for 8 months.

Data from the X-ray spectra (shown in blue and green) show that the interstellar gas has been heated to millions of degrees by the passing shock wave caused by the supernova. The infrared data (in yellow and red) show dust that is radiating at several hundred degrees below zero, which is warm compared to our galaxy’s dust. This thing was a class 1A supernova that was caused when a dead star (a white dwarf) sucked a bunch of material off of a companion star. RCW 86 has gotten large quicker than it should have. It is postulated that the star released gasses and blew out a region of low-density prior to going supernova, allowing the explosion to reach a large area very quickly. It is pretty neat that we know all of this partly thanks to the work of scientists 2000 years ago. Imagine what we will know about the universe a couple thousand years from now.

Advertisements

Fun with dry ice

28 Oct

Dry ice is a pretty amazing substance. It is made of solid CO2, and when it warms up it goes straight from the solid phase to the gaseous phase. This is called sublimation. There are many cool things you can do with dry ice. It’s a good way to teach about hot and cold (which is just the lack of heat), and the phases of matter. You should wear gloves and goggles for all of these.

Cool thing #1: Take a quarter and press it down against the dry ice. The gas escaping from around the quarter makes a loud noise. Be careful because the quarter might go flying.

Cool thing #2: Take some PVC pipe and create a tube with one end stopped up (it helps if the top of the open side is curved). Put a piece of dry ice in the bottom of the pipe and dip the open top end in some bubbles (like the kind you blow bubbles with). The gas form of the dry ice is many many times larger in volume than the solid form, so the gas escapes through the open end and blows bubbles for you. The cool part is that the bubbles are full of fog, and they sink quickly. When they hit the ground and pop, the fog escapes and it looks pretty cool.

Cool thing #3: Use the same PVC pipe from Cool thing #2 (you don’t need the curved piece for this), and attach a balloon to the top. Be sure that it is well sealed. Like I said, the gaseous form of dry ice is much larger in volume than the solid form, so it will blow up the balloon for you. It will even pop it if you hold it on for long enough. Definitely wear gloves and goggles.

Cool thing #4: Make root beer. Use dry ice to carbonate your beverage. You can find the recipe here. I suggest playing with the root beer extract and sugar amounts, tasting as you go so you get it just the way you like it!

Cool thing #5: Halloween approaches. So of course I must mention that you can make traditional Halloween sciency-looking potions by adding dry ice and food coloring to water in a beaker, flask, cylinder or burette of your choice. Don’t forget the clamps, goggles, lab coat and crazy hairdo.

There are all sorts of cool stuff you can do with dry ice, from making vortex cannons to quarter whistling. If you want to share any of your own ideas, leave a comment below.

Fun with phase

26 Oct

Pretty awesome show for a bunch of simple pendulums. The period of the pendulum, or the time it takes for the pendulum to swing from one side to the other and back, is dependent on the length of the string. All the cool shapes and patterns are just the result of the differences in period. Patterns appear and then disappear as the pendulums get in and out of phase with each other.


Bacteria changes host’s sex

25 Oct

I have heard of a lot of strange bacteria, but I have to say that Wolbachia is the weirdest. Estimates show that wolbachia is present in 65% of known species of insects. It lives inside the cells of its hosts, not just the guts, skin and orifices. This thing has a huge variety of mechanisms for ensuring its proliferation. Wolbachia can change its hosts’ sex, kill its offspring or make it fertile depending on which suits the bacteria’s needs. This may seem like a lot of leeway to give a bacteria that lives symbiotically with a host, but wolbachia provides enough benefits to make it worth it. Wolbachia actually encases dividing cells and helps ensure that the new cell has the right number of chromosomes (picture above shows wolbachia proteins in green, chromosomes in blue).

Wolbachia has learned how to hitch rides on proteins within the host to get where it needs to go, and generally gives the impression of a kid in a candy store going crazy. Genetically, it is a relatively simple bacteria, with a lot of raw material for adaptation and rapid evolving. We are only beginning to understand what this thing is capable of. Crazy stuff! Check out more here.

Levitation

24 Oct

This is pretty amazing. Let me tell you a bit about what is going on here. Superconductors do not like magnetic fields. If possible, the superconductor will expel the magnetic field from its interior. This is called the Meissner Effect. But in this case, the superconductor is a super-thin wafer of ceramic on top of a sapphire substrate. It is so thin that the magnetic field does penetrate the superconductor, but in discreet quantities called flux tubes. The flux tubes penetrate weaknesses in the superconductor, like grain boundaries. Any spacial movement of the superconductor would change the position of the flux tubes. The flux tubes really want to stay in the grain boundaries, so the entire superconductor is locked in place. Strongly.

Image courtesy of Tel-Aviv University

Volcanoes on other planets

22 Oct


To wrap up Volcano Week at Physics Fascination, I just want to note that there are volcanoes on planetary objects other than earth. Check out this photo of the massive Tvashtar volcano on Jupiter’s moon, Io. Or watch a video of images here. Amazing.

Pompeii

21 Oct

In some cases, volcanoes offer us a glimpse of the past. The Roman city of Pompeii was completely buried by the eruption of Mount Vesuvius in AD 79. For two days, the ash and pumice poured from the sky until the entire city and its occupants were buried under between 13 and 20 feet of grey. Ironically, the eruption occurred the day after Vulcanalia, the festival of the Roman God of fire.

The city is so well preserved that we are offered a snapshot of what life was like for the Romans of that time. Graffiti in the streets show us what every day Latin was like. Family portraits hang in houses. Signs above shops show us the clever marketing of the vendors. Dogs on leashes are chained up outside shops. And huddled human figures show us what those last horrifying moments must have been like.