“The Universe is very, very big. It also loves a paradox. For example, it has some extremely strict rules.
Rule number one: Nothing lasts forever. Not you or your family or your house or your planet or the sun. It is an absolute rule. Therefore when someone says that their love will never die, it means that their love is not real, for everything that is real dies.
Rule number two: Everything lasts forever.” -Craig Ferguson
When you think about the Standard Model of particle physics, you very likely think about all the matter, energy, particles, antiparticles, forces and interactions of the Universe. And you might legitimately worry that this is all there is. With the LHC confirming that there’s no low-scale supersymmetry or collider-accessible extra dimensions, and that all the decays and branching ratios align with the Standard Model’s predictions, that worry seems well-founded.
Changing particles for antiparticles and reflecting them in a mirror simultaneously represents CP symmetry. If the anti-mirror decays are different from the normal decays, CP is violated. Image credit: E. Siegel.
Never fear; we know there’s more! The Standard Model may be wonderful for what it does predict, but we know with absolute certainty that it can’t be everything. From dark matter to massive neutrinos, from the strong CP problem to baryogenesis and more, there are five very strong pieces of independent evidence that show there’s more to the Universe than what we presently can explain.
The early Universe was filled with matter and antimatter amidst a sea of radiation. But when it all annihilated away after cooling, a tiny bit of matter was left over. Image credit: E. Siegel.