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I bet you didn't know that this thread would have a part 2
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Finding myself quoted as the source of a fact in this thread makes me feel like Wibbs.secondrowgal wrote: »I saw this on another thread, but apparently goldfish were never meant to be kept in bowls! They would have been transferred to bowls for the duration of a dinner or an event, as a decoration, and to show them off, but then returned to their pond/larger aquarium afterwards. Keeping goldfish in bowls is cruel as they have stunted growth and reduced lifespan.
They need about 300 litres of water for a single fish and an additional 50 litres for each extra fish. To correctly house a single goldfish in an aquarium, you'd be looking at a 3ft x 2ft x 2ft tank!
https://www.boards.ie/vbulletin/showthread.php?t=2058003700&page=2
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Nevaeh Shaggy Destroyer asked this question in another thread and I was thinking about how to explain it. It also gives a chance to add a bit about the Higgs boson that was found in 2012.Nevaeh Shaggy Destroyer wrote: »Why are CP violations observed in certain weak force decays, but not elsewhere?
CP violation is very important because it's the only way the laws of physics treat matter differently from antimatter. Without it the universe would be filled with nothing but light and other forms of radiation.
P is a transformation where you change how particles are spinning, i.e. change clockwise to anticlockwise
For C you replace every particle by its antiparticle.
Electromagnetism and the Strong Force have these as symmetries because particles spinning clockwise and counterclockwise emit them both with the same strength and the forces are felt as strongly by a particle and its antiparticle.
In the 1950s based on the Electromagnetic and Strong Forces it was thought that the Weak Force must respect P symmetry as well. There were certain particle decays associated with the Weak force that didn't fit into theories at the time, but nobody really considered this to be related to P symmetry. Two Chinese researchers Tsung-Dao Lee and Yang Chen-Ning at Columbia University in New York had the idea that all of these decays could be explained if the Weak Force broke P symmetry and came up with a theory of the Weak Force that let P be broken.
Their idea was that only particles spinning counterclockwise or antiparticles spinning clockwise can emit the weak force. So changing the way a particle was spinning would shut off its Weak force field. They weren't certain how to test this and so turned to another Chinese researcher at Columbia, C.S. Wu:
She understood their theory implied that frozen Cobalt held in a magnetic field would decay slightly differently from how other theories predicted. In 1956 she found that it decayed just as Lee and Yang's theory predicted. This is her with the equipment:
Immediately it was known that C-symmetry would be violated because it would turn an particle spinning counterclockwise into an antiparticle spinning counterclockwise, which don't emit the weak force according to the Lee-Yang theory. This was observed shortly afterward.
Now people expected the combination CP symmetry to still hold because it does the change:
counterclockwise particle -> clockwise antiparticle
and both of those interact with the Weak force in the Lee-Yang theory.
Another step was needed to see that even this fails to hold. It was first seen experimentally in 1964 in the Brookhaven National Laboratory by James Cronin and his group.
This was during decay studies of a type of particle called a Kaon. Kaons have two ways of decaying into neutrinos and electrons that should happen equally often, but one of them was seen to occur 0.3% more often. This could only happen if CP was violated. Something no theory predicted.
The answer lay in how quarks and other particles create the weak force.
In order to emit the weak force quarks and electrons have to mix with their heavier cousins. That is an up quark for example has to combine with the charm quark. That quarks can't just emit the Weak Force themselves without mixing was recognised by an Italian physicist Nicola Cabbibo:
And he added this to the Lee-Yang theory allowing it to explain even more particle decays. However still not the CP violating ones.
Two Japanese physicists Toshihide Maskawa and Makoto Kobayashi however realised that if there were a third generation of quarks, not just up/down and charm/strange, then it would be possible for the mixing between the quarks to work differently for matter and antimatter, because how much the third generation added to the mix could be slightly different between matter and antimatter (the maths forces it to be identical for two generations)
They made this alteration and matched exactly the decay rates for the Kaon and in the process predicting two new quarks from a third generation, the top and bottom. These were observed directly later in the 80s. Quantum Mechanics says that there has to be the same number of quark and electron generations, so it also forced a third type of electron to be predicted: the tau. Four other Japanese physicists later figured out how to describe the mixing between the generations for electrons (it's a good bit more difficult than for quarks mathematically).
Without this CP violation the laws of physics would treat matter and antimatter identically and they would have both annihilated the other in the early universe. The violation however means that slightly more matter was produced giving the world we see today.
The third generation of quarks and electrons don't really do much today. Occurring almost never in matter throughout the universe and making so little difference when they do rarely appear that their influence is irrelevant. However they were crucial early on because they let CP violation happen.
Once this was all done there was only one problem with the whole theory of the Weak Force. The particles responsible for the force had a mass. According to quantum mechanics they can't. No particles responsible for forces can have a mass. All the researchers I mentioned before ignored this problem by inserting a mass in their calculations. However this wouldn't work forever. Putting the mass in would cause infinities to pop up in the theory somewhere.
Through a combination of the work of Steven Weinberg, Abdus Salam, Sheldon Glashow, Peter Higgs and François Englert it was found that the only way the weak force carriers could be massive without breaking quantum theory was if they weren't the true force carriers. That is if the Weak Force wasn't originally a fundamental force of nature. The idea was that back in the early universe there were two other forces that are no longer easily visible. However at some point very early on a field called the Higgs field became very strong everywhere in the universe. This masked the true fundamental forces in a manner similar to how light comes out dimmer and brown through muddy water.
Instead what managed to shine through the mud of the Higgs field was an altered imperfect reflection of the original two forces. Two new forces: Electromagnetism and the Weak force. This idea was verified in 2012 when a small amount of the Higgs "mud" was discovered in the Large Hadron Collider housed beneath the Franco-Swiss border.
As an interesting side note, as far as we can tell life (at least as we know it) would not have been possible under the original forces as stars probably wouldn't have worked correctly.0 -
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Ancient Roman women liked their elaborate hairdos, and trends changed frequently.
Which meant that when they had busts sculpted of them, there was a danger that the busts would quickly become outdated and unfashionable. It was expensive to get new busts commissioned, so they came up with quite a clever solution: make the hair detachable. When the style changed they would only need to update the 'wig' on the sculpture.0 -
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Another interesting thing about Roman busts is that they were far more realistic and representative of the person than say the Greek, where people were prettied up. Romans were more warts and all. So if you had a chubby face, or crooked nose or balding etc that's how you'd be carved. Emperors depending on the individual were more godlike and prettied up for propaganda purposes.
They were also of course painted to look as lifelike as possible.
Rejoice in the awareness of feeling stupid, for that’s how you end up learning new things. If you’re not aware you’re stupid, you probably are.
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