The Low-Temperature Fairground

Well, There are not enough comments over here to keep this thing going, but I love my physics so much, I will do so. However, here's a point which piques the curiosity....

Superconductivity. Superfluidity.

What are they?

It happens at low temperatures. Low temperatures.

Very low temperatures.

Ok, without the details, here is what you see...

1. Substances conduct current for years without a power source.

2. Liquids appear emptier than empty space.

3. Liquids fall out of their own containers by themselves.

Helium is called a superfluid and has been well-studied. It seems to look like a combination of two different Heliums (maybe "Helia"??). Called Type 1 and Type 2. It exhibits superfluidity according to how near it is the Lambda point at 2.17 K. Only when it reaches 2.17 K does it become truly superfluid.

These are number 2 and 3 above. Technical term for No2 in "viscosity" - that is a word that means how hard it is to move a hand through the fluid. For instance, it is more difficult to move your hand through crude oil than through water, and more difficult to move your hand through water than any gas (gases and liquids are both called fluids in physics). As for the liquid Helium, is is easier to move anything through it than a gas, or even empty space. It feels like it is not there. It has zero viscosity.

No 3: A strange property of zero viscosity is that there is no resistance to the flow. The molecular movement inside the Helium is enough to drive it up the sides of any container ( from which it has no friction at all ), climb over the rim, and run down and drip from the lowest point.

As for metals, which is No 1 above, or more specifically, ceramics, the behave like there is nothing to stop the electricity flowing.

Ceramics are studied because their "lamba point" is much higher than 2.17 K. In fact, and this is not my field, but ceramics were close to having a lambda point at close to 79 K. This is significant because this is the boiling point of Nitrogen, and Nitrogen is much more common than Helium (Nitrogen is 78% of our atmosphere, Helium can only be gotten from rocks), and so is much, much cheaper.

However, for our coils, they have to copper, as here we have the conservation of energy again, as the advantage gained in the higher temperature superconductivity, is offset by the fact that ceramics are not good conductors.

Copper has lots of free electrons in it, Ceramics do not, and we can get a bigger non-resistive current if we are prepared to pay for the more expensive Helium.

Upshot is,

Copper: bigger current, lower temperature for switching superconductivity on, therefore more expensive Helium is needed.

The Ceramics: smaller current, but higher temperature for superconductivity switch on, therefore cheaper because maybe only Nitrogen needed.

The LHC needs copper to power the large magnets because the particles go so fast we need the magnets to be far more powerful because they have to turn the now heavier particles because of special relativity ( lol too many "because's )

Swings and roundabouts with a vengeance.