Great Mysteries of Physics: do we really need a theory of everything?

• While each of its main theories works extraordinarily well, they clash also with each other – leaving physicists to search for a deeper, more fundamental theory.
• But do we really need a theory of everything?
• Our two best theories of nature are quantum mechanics and general relativity, describing the smallest and biggest scales of the universe, respectively.
• If it could, it would indicate that quantum theory might ultimately be more fundamental than general relativity, accounting for four out of five forces – suggesting general relativity ultimately may need to be modified.
• If it couldn’t, that would shake up physics – suggesting we may need to modify quantum mechanics, too.

What about other mysterious properties?

• And what about other mysterious properties such as dark energy, which causes the universe to expand at an accelerated rate, or dark matter, an invisible substance making up most of the matter in the universe?
• “Dark matter and dark energy are most of the matter energy content in the universe.
• So it’s not really a theory of everything if it’s not accounting for most of the matter energy content in the universe,” she argues.
• “One of the strengths that people will point to with string theory is that string theory built on quantum field theory,” explains Prescod-Weinstein.