4mo ago

New quantum theory of gravity brings long-sought 'theory of everything' a crucial step closer

phys.org New quantum theory of gravity brings long-sought 'theory of everything' a crucial step closer

At long last, a unified theory combining gravity with the other fundamental forces—electromagnetism and the strong and weak nuclear forces—is within reach. Bringing gravity into the fold has been the goal of generations of physicists, who have struggled to reconcile the incompatibility of two corner...

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phys.org /news/2025-05-quantum-theory-gravity-sought-crucial.html

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Although the theory is promising, the duo point out that they have not yet completed its proof. The theory uses a technical procedure known as renormalization, a mathematical way of dealing with infinities that show up in the calculations.
So far Partanen and Tulkki have shown that this works up to a certain point—for so-called 'first order' terms—but they need to make sure the infinities can be eliminated throughout the entire calculation.
"If renormalization doesn't work for higher order terms, you'll get infinite results. So it's vital to show that this renormalization continues to work," explains Tulkki. "We still have to make a complete proof, but we believe it's very likely we'll succeed."

ELI5 why this is bullshit again?
- Not necessarily this one. But in general the problem with most quantum gravity theories is that they are made from mathematics alone. All the successful theories were developed from experimental results. From real data.
  You can say a lot with just mathematics. Doesn't mean that it is real.
  A good theory explains the current tests we have and can make predictions about new tests. Otherwise it is useless.
  
  All the successful theories were developed from experimental results
  The more I think about this, the more I'm not sure I 100% agree... For example, special relativity essentially came from the observation that Maxwell's equations were not Galilean invariant, and instead invariant under this weird other group (what we now call the Lorentz group); and QED essentially came from Dirac wanting to take a "square root" of the Klein-Gordan equation.
  (Of course, real history is more intricate than this.)
  
  All the successful theories were developed from experimental results. From real data.
  This is not really true. Lots of very well tested theories in physics came from math first, and then experimentation upheld them.
  Einstein developed general relativity based on mathematical principles (Riemannian geometry and the equivalence principle) with little direct experimental input. And then successfully predicted the light of distant stars bendng around the sun.
  Paul Dirac formulated a relativistic equation for the electron. The math naturally predicted the existence of a positron which was discovered years later.
  Peter Higgs and others proposed the Higgs field to explain why particles have mass within the Standard Model, in 1964. It wasn't detected in experiments until 2012.
  Maxwell’s unification of electricity and magnetism led to the prediction of electromagnetic waves. 20 years later Hertz detected them.
  Just months after Einstein published general relativity, Karl Schwarzschild found a solution predicting black holes. With no data at all! Sure enough, we've observed them and their effects many times.
  Mathematics often leads the way in physics.
- When the theory of everything happens, it won’t be phys.org reporting it.
  Until then, you’ll see lots of blogs reporting various papers to get those clicks.

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