Back about 2000 years ago, the Greek scientists were becoming fascinated with magnetism when they stumbled upon lodestones, a naturally occurring magnet.

Lodestone is a piece of magnetite, an iron oxide, which produces a strong magnetic field. Now, to be clear, not all magnetite is magnetic (it won’t stick to your fridge by itself) but being a type of iron, all magnetite is attracted to a magnet (technical word: it’s ferrimagnetic).

The creation of a lodestone (magnetized magnetite) is still a bit of a mystery, but the leading hypothesis is that the magnetic properties were picked up after being struck by lightning. It’s sort of a geological superhero origin story. This theory is supported by the fact that a lodestone has never been found very far from earth’s surface.

The word magnet originates from Magnesia, which was a region of Greece where these original lodestones were popping up.

Magnetite lodestones are one of only two minerals that have been found to be naturally magnetized on earth. Which begs the question; how do the real estate agents and plumbers manage to get their hands on so many lodestones?

Most of the magnets we encounter on a daily basis have been artificially magnetized. You can start with any ferromagnetic material. (most commonly ferrite, a ceramic compound containing iron oxides) The simplest way to turn that into a magnet would be to rub it against something that is already magnetized in the same direction many times. (it’s sort of like you are “combing” the electrons)

To manufacture the strongest magnets, the material must be heated above the Curie temperature, which varies depending on the material, putting it into a receptive state. It’s then subjected to a strong electromagnetic field. As it cools, the magnetism remains in the material. If it’s ever re-heated past that Curie temperature again, it could lose it’s magnetic strength. I learned this the hard way when trying to use a hot glue gun on rare-earth magnets.

Now, this is just the tip of the iceberg for the fascinating science behind magnets. There is a lot to think about next time you go to clip up your grocery list.

• Source: Magnet – Wikipedia
• Good Book: Magnetic Magic – from Klutz Press, I had this book as a kid and loved it. Comes with magnets and a steel book cover to keep them on.

So, BEHOLD! The first, and hopefully not last, live video LSNED!

(Watch the video on YouTube)

In the video I cover a few experiments and “science tricks” using balloons that kids are encouraged to make themselves and try at home. Be sure to stick it out for the bonus experiment at the end, after the break, which may well be my favourite of the batch.

• Good Book: Most of the experiments in the video came from my own memory, but I also had a flip through this “Balloon Science” book for additional ideas.

I was talking with an amateur astronomer this morning who, in reference to another astronomer and blogger I mentioned, said “He’s great… except that he believes in black holes.”

The comment caught me off guard. Up until that moment I had no idea that “black holes” was a topic of controversy. I dug into research as soon as I got home.

A black hole is the name for a small body of matter floating in the cosmos that is incredibly dense. Like the entire sun being compressed into a ball the size of a city. It is black because the density creates such a strong gravitational field that light itself is pulled back into itself.

If light can’t get out, we can’t possibly see it to prove it exists. However, astronomers observe the outside affects of a black hole and determine, though they can’t point to it, exactly where the black hole must be.

Just like earth and our neighboring planets orbit around the sun (being the most dense, and thus our gravity boss), astronomers can see stars orbiting around a spot in space. Something must be there at the center creating the orbit, and the best guess is that the something is a black hole.

Another way to spot a black hole is from bursts of x-rays. As a star gets too close to a black hole it begins moving faster and faster, heating up in the process. When the gas of the star reaches such temperatures it begins to emit x-rays. Eventually, as the star spirals ever closer to the black hole it too will become invisible, but outside of the “horizon” of the black hole (the tipping point of the gravitational field, a point of no return) we can observe these strange happenings. The clues add up to the presence of a black hole.

Proving the existence of black holes seems to be a case of “if it walks like a duck and talks like a duck…”, which leaves room for doubt as to whether or not there is a big duck at the center of our galaxy. Let’s take a look at the other side of the argument.

The anti-black-hole debate centers on one sticky issue, “The Information Paradox”. All the details are well beyond my understanding, but it boils down to this. You’ve perhaps heard of the law of conservation of energy… energy cannot be created or destroyed, but merely changed from one form to another. (A car’s forward momentum, through the friction of the brake pads, turns to heat dispersed into the air, etc.)

Well, there is a theory of quantum physics that says there must be a conservation of information. The information in question is sort of like DNA for particles at the smallest level. If matter was to collapse into a black hole, unable to escape, this information would no longer be accessible to the universe. To theoretical physicists, that’s a big problem.

Some of the proposed solutions involve fancy words like “11-dimensional supergravity” and other string-theory brain-busters that are well beyond the scope of the LSNED blog. If you will allow me to over-summarize, conveniently avoiding 500 more words of clumsy explanation, the leading anti-black-hole theory (the Holographic principle) is essentially arguing that a black hole is a mirage of sorts. Rather than a true physical black hole that gobbles up matter never to be seen again, it is a cosmic illusion that just appears that way to our simple three-dimensional brains.

Perhaps I will revisit that another day.

• Source: Black Holes – NASA
• Source: Black Hole Information Paradox – Wikipedia

There is a lot of hub-bub about a neutrino that was witnessed moving faster than the speed of light, a feat which was deemed impossible by Albert Einstein’s theory of relativity. The science community is working overtime to figure out if the experiment can be repeated and confirmed, as it would have a major impact on our understanding of physics.

I’ve been doing some reading to get a better grasp of what, exactly, a neutrino really is. It is a rather elusive particle, which adds an air of mystery (not to mention difficulty) to any observation experiments.

One thing I do know is that, at this very second, billions of neutrinos are passing straight through your body without even slowing down.

The existence of the tiny neutrino particle was proposed as a solution to some “missing energy” observed in radioactive decay. It was theorized that some sort of particle was carrying this energy away. Shortly thereafter Enrico Fermi worked out the specific role that the mystery particle needed to fill, dubbing it the neutrino due to it having no electromagnetic charge… the particle was neutral.

The fact that it is neither negatively or positively charged is what makes it so hard to detect. It has so little interaction with other particles that it can zip right through objects without stopping, slowing, or changing direction. All the neutrinos that are generated from our sun not only pass through your body, but right through the core of the earth and out the other side on their journey across the universe.

That’s the trouble. If they pass through the solid granite of the earth without a second thought, how can our scientists “capture” neutrinos in any sort of observation equipment? Studying neutrinos is a bit like trying to spot bigfoot… if bigfoot was also invisible and moving about the speed of light. All they have to go on is the footprints and broken branches left behind.

The original experiment that caught a glimpse of neutrinos occured in 1956. There was a big water tank. While the vast majority of neutrinos pass through silently, due to sheer volume they would sometimes collide and interact with protons in the water. This would create positrons, which would in turn create a pair of gamma rays if it collided with an electron. The gamma rays excited a scintillator, which is  a material that absorbs gamma rays and emits light. Finally, the tiny flashes of light were recorded by sensors inside the tank.

It was a Rube Goldberg machine on the atomic scale, but it worked. The experiments recorded about three light flashes per hour. More intricate, modern experiments can not only catch the existence of neutrinos, but capture information about the direction and speed of travel. The largest neutrino-catcher actually uses the solid ice of Antarctica as its water tank. Through this we are able to see evidence of cosmic explosions and supernovas far beyond the range of our telescopes.

The complexity required to observe neutrinos is why physicists are being extremely cautious about this new “faster than light” hypothesis.

Does this really explain what a neutrino is? Perhaps I should just leave it at the description by Frederick Reines, telling us that a neutrino is “the most tiny quantity of reality ever imagined by a human being.”

• Source: All About Neutrinos – IceCube South Pole Neutrino Detector

Dear LSNED,

Why do I always burn my mouth when eating potatoes? Why do they stay so hot?

-Hot Tater

Dear Ms. Tater,

It is true that, long after the asparagus has gone cold, your baked potato will be deliciously, or perhaps dangerously warm. The reason behind this is the high heat capacity of a potato.

Technically speaking, heat capacity (or “specific heat”) is how much heat is needed to change the temperature of a substance by one degree. This specific measurement lets you compare the heat capacity of different things on an even scale. Potatoes, above freezing, weigh in at 3.43 kilojoules of energy to raise 1 kilogram of potatoes one degree centigrade.

However, asparagus has a specific heat of 3.94, meaning it holds heat better than a potato. So, what now?

Well that is a measure of the amount of heat held per a specific weight of the vegetable in question. Potatoes trump asparagus in the density department. With more than twice as much density, an equal serving of potatoes and asparagus would have the potatoes staying warm twice as long.

Another important part of your supper’s ability to retain heat is conductivity and surface area. The heat from your food gets transferred to the cooler air around it, and the more it is in contact with the air, the faster this transfer can take place. For this reason long skinny french fries will cool much faster than a solidly round baked potato. (a sphere is the best shape for minimal surface area to maximum volume)

So when your asparagus comes out of the oven at the same time as your potatoes, start with the greens to save yourself from a burning mouth.

Warmly Yours,

• Source: Specific heat capacity of Foodstuffs - The Engineering Toolbox
• Source: Heat Transfer and Cooking – Cooking for Engineers

It’s easy to shrug off electricity as a mundane part of life, but the more I think about it, the more it seems like magic. Electricity is the passing of electrons, the tiniest part of an individual atom, down the line from one atom to another like a hot potato. This electron flow is what occurs along our power cords.

Positively charged electrons surge towards negative charges like water going downhill. If we put things like lightbulbs in the path, we can put the electron flow to our own use.

What our electrical engineers have accomplished over the centuries is a thing of beauty. Let’s take a closer look at an electrical transformer to see how nature has been reigned in.

The goal of a transformer is to convert the voltage of an electric current to a different voltage. Most commonly seen in the “wall wart” that takes the 120 volt electricity from the wall socket, and converts it to 7 volts to charge your mobile phone without causing it to explode.

The construction of a transformer is essentially simple. Just three parts. One incoming wire, one outgoing wire, and a specially shaped hunk of iron. The wires are wrapped around the opposite sides of the iron core, and there you have a transformer.

The amount of conversion depends on the number of times each wire is wrapped around the core. To convert 100 volts in to 10 volts out, you could wrap the incoming wire around 100 times, and the outgoing wire gets wrapped 10 times around the core.

The two wires do not touch. The incoming wrapped wires turn the iron core into an electromagnet, and through the process of induction, the magnetic flux creates voltage in the second outgoing wire. See, I told you it was like magic.

Your car has a transformer in it, called the ignition coil, that converts the electricity from your 12 volt battery into a charge of 20,000 t0 50,000 volts to send to the spark plugs so they can ignite the gasoline. That takes a lot of turns of the wire!

Of course, in the realities of electrical engineering transformers have a lot of added complexity to increase efficiency and safety, but at their core (literally) it all comes down to wound up wires.

• Source: Transformer – Wikipedia

When you mix regular off-the-shelf cornstarch with regular from-the-tap water you get yourself a physical anomaly. A substance that can be both a liquid and a solid at the same temperature.

It’s called a non-Newtonian fluid because it doesn’t behave according to the what Sir Isaac Newton discovered about the viscosity (flow) of liquids. In this case the corsntarch-water goo, often called “oobleck”, will slowly pour like a thick fluid under normal circumstances, but if stress is added, the fluid will firm up and break like a solid.

If you have the budget to fill a swimming pool with it, you can easily walk straight across the top as each footstep applies force to the oobleck, firming it up under your foot. However, if you stop, you will sink in, and have a very difficult time getting out. Any attempt to pull yourself up will again firm up the fluid in your path.

You can make some for yourself. Put some cornstarch in a bowl, and slowly stir in water. Keep adding water and stirring slowly until you feel it thickening up. The approximate recipe is 2 parts cornstarch to 1 part water, and just enough food colouring to make it more exciting than mathematics. You’ll know when you get it just right as you’ll be able to pick it up, and roll it into a rubbery ball in your hands. But the moment you stop rolling it will melt and drip back into the bowl. Or, more likely, all over the floor. This is messy science.

The reason this happens is that the structure of cornstarch comes in long chains of atoms bonded together. This is called a polymer. When things are flowing slowly, the chains can slip past each other, but as things speed up the chains get tangled and stuck making the structure more solid. It’s like trying to run through a crowd of people. You have to move slow if you want to get anywhere.

Watch this demonstration of some oobleck placed on a speaker cone. A low-frequency hum is put through the speaker, causing vibrations. As the stress is applied to the fluid it begins to come to life, building solid structures.

Link to Youtube Video

Other everyday non-Newtonian fluids included silly putty, which can stretch or snap depending on how fast you pull it.

Also, ketchup… which explains why it’s so slow to come out of the bottle. It requires a certain amount of force (usually gravity) before it will start flowing, but once it starts it moves easier. Whenever you drown your french fries in a sudden splurge of ketchup, it’s not Newton’s fault.

• Source: Goo Recipe – Colorado State Physics