New Forces of Nature - A Quest for a Grand Unified Theory

[Hyperreality]

"New Forces"

Will physicists find any new fundamental forces of nature, and how would we ever know we have found all the fundamental forces in the universe? Might this question be the corner stone to a grand unified theory? Or do we expect a solution which indicates the number of fundamental forces from the grand unified theory?

 

[marcus]

... how would we ever know we have found all the fundamental forces in the universe? ... do we expect a solution which indicates the number of fundamental forces from the grand unified theory?

as I understand how scientific progress works, we never can know that a theory is right

experiments can only prove theories are wrong

the good theories are the ones which have risked making predictions about experiments with unknown outcome (so they can be tested) and which have survived all the tests up till now.

therefore suppose, as you imagined, that in the future you have a Grand Theory which explains that there should be exactly these four and no others.
then (if only that theory could be trusted) we have already found all four fundamental forces

but what guarantee would there be, in your imagined scenario, that such a Grand Theory is correct? Even if it has passed all the tests so far, and
conforms with all known experimental observations so far, perhaps tomorrow an experiment will go against the Grand Theory and it will be discarded. It might even replaced by another Grander theory in which there is room for FIVE fundamental forces.

So one can never know how many fundamental forces there are, even if one has an elegant successful theory that says how many there should be.

It is not possible to prove physical theories correct, one can only test them repeatedly and keep one's mind open to the possibility that they could one day fail.

 

[Mike2]

as I understand how scientific progress works, we never can know that a theory is right

I beg to differ. The fundamental premise of science is that all things have a logical explanation. If that is correct, then all of physics should be reducible to logic. If that ever happens, then we will know that our theory is correct, that things could not be any other way.

 

[marcus]

I beg to differ. The fundamental premise of science is that all things have a logical explanation. If that is correct, then all of physics should be reducible to logic. ...

that was the view of science before Bacon (1561-1626) and Galileo

it was the approach in Aristotelian science practiced by the medieval Scholastic philosophers

however Francis Bacon and others in the 16th - 17th Century developed the empirical approach and argued against your position. The past 4 centuries of progress can arguably be attributed in part to the Baconian revolution, in which your position (that all of physics should be reducible to logic) was abandoned. Historians of science therefore usually take the view that
we owe a lot to Francis Bacon. he did us a big favor by helping us mature beyond the view of science which you present here.

Here is Stanford encyclo of philosophy article about Francis Bacon
http://plato.stanford.edu/entries/francis-bacon/
Perhaps we should all know him better and try to understand how he came to his revolutionary insight about science

 

[ohwilleke]

Will physicists find any new fundamental forces of nature,

Certainly not outside the realm of possibility. The best bets, IMHO, would be (1) a fundamental force that would hold together quarks if they turn out to be composite particles, (2) a large scale repulsive force that explains "dark energy" cosmologically, and (3) some force associated with a Higgs field or pertabations in a Higgs field.

and how would we ever know we have found all the fundamental forces in the universe?

We won't, but will have a good clue when we stop observing phenomena that we can't explain with our existing theories.

Might this question be the corner stone to a grand unified theory?

I'm thinking more along the lines of a decorative gargoyle.

Or do we expect a solution which indicates the number of fundamental forces from the grand unified theory?

I don't expect that. I would be less surprised, however, to see "higher order harmonics" of existing know forces with quite slight adjustments to the main effects (as an analogy one might think of Newtonian gravity as a first order effect, gravitomagnetism as a second order effect, and the effects of GR not explained by Maxwell like equations for gravity, e.g. quadratic impacts of mass velocity on gravitaitonal effects, as a third order effect; one could imagine seeing "fourth order" effects in gravity, and higher order effects in other forces).