# Four forces or just three?

• CuriousGeorge1
In summary, the nature of gravity as a force or a consequence depends on the context and the mathematical formulation being used. In classical mechanics, gravity is considered a force, but in more sophisticated approaches, it may be seen as a consequence. The ultimate goal is to unify all forces into one theory, but currently, there are three known forces in nature, with gravity being the most challenging to incorporate into this unified theory.f

#### CuriousGeorge1

Since gravity is caused by mass deforming spacetime, is gravity actually a force or just a consequence? Are there really 4 forces in nature or just 3?

What does "really" mean?

“Really” used for emphasis, drop the word and question still stands. Are there four forces in nature or just 3?

“Really” used for emphasis, drop the word and question still stands. Are there four forces in nature or just 3?
What do you mean by "forces"?

The point is that your question is not answerable because it is based on a false assumption: that you can frame a question about physics in vague ordinary language that somehow has a precise answer. The only precise answer is the mathematical models that physicists use to make predictions, and those models can be described in vague ordinary language in multiple, different ways. There is no one "right" description that will answer your question one way or the other.

topsquark
Since gravity is caused by mass deforming spacetime, is gravity actually a force or just a consequence? Are there really 4 forces in nature or just 3?
Electromagnetism and the weak force have been unified, so the max right now is three. The goal with TOE is to get it all down to just one. Connecting the Strong force to Electroweak seems close. Getting Gravity to play along looks harder. But really anything is possible.

https://en.wikipedia.org/wiki/Grand_Unified_Theory
https://en.wikipedia.org/wiki/Theory_of_everything

In the narrower sense of "Is gravity a force?", you'd really need to have the TOE to get a final answer to that. Otherwise it starts turning into linguistics. Right now I'm not aware of any real objection to calling Gravity a force, (particularly for practical applications such as spacecraft ) but that might change someday.

topsquark
is gravity actually a force or just a consequence?
'Force' as a construct in physics actually belongs to the specific viewpoint of 'Classical mechanics' and is not necessarily present in some alternative ... approaches.
If your actual approach is based on classical mechanics (likely the case when you work with everyday problems), then it's a force, and since classical mechanics has not much to do the unified theories, you may need to account for quite disturbing number of 'forces in nature'.

If the problem you are working with requires a more sophisticated approach, then gravity will be more and more like a consequence, and depending on the depth required by the problem, you might be down to three or just two forces interactions.

All depends on the required depth of the approach, and these answers are still the same without any controversy.
It's just ... not simple.

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topsquark
Yeah, this might sound perplexing, but we often use terminology that was formerly used in classical mechanics that is also confusingly being used in quantum mechanics. Consider many of the terminology used in quantum mechanics to have certain context to what it actually refers to.

Even in the most simplest thing like Coulomb force Interaction (between electrons), which you may have a fairly good understanding in electromagnetism, will have a relatively math-heavy formulation in quantum mechanics (i.e. direct term and exchange term). However, few people confusingly call these terms as "direct force" and "exchange force". And then you have words like "force carrier" which is something else. So like everyone just stated here, "force" really depends on the context, and at what mathematical formulation we're exactly talking about.

Thanks to all of the above respondents for your replies. i was only considering force in relation to classical physics and TOE efforts to unify gravity with the strong/weak/EM forces. I now see my question in a broader context.