What force in the universe is the strongest or the most powerful?
Asked by: Regal Patel


There are four fundamental interactions that we know of. These four interactions account for all observed forces. These interactions are: Strong Nuclear, Electromagnetic, Weak Nuclear and Gravitational.

The strongest of these four is the Strong Nuclear. However, since this interaction operates at a very short range inside the nucleus (as little as 1 fm - which is a femto-meter or 10-15 meters) it is not the sort of force that we experience in everyday lives. This interaction acts between the nucleons (particles in the atomic nucleus - protons and neutrons which are made of quarks) and it is responsible for keeping the nucleus together. This interaction is mediated by so called gluons.

Strong Nuclear100Short (1 fm)Gluons (G)
Electromagnetic1LongPhotons ()
Weak Nuclear10-10Short (1 am)W+, Z0, W-
Gravitational10-40LongGravitons (g)
The next strongest interaction is the Electromagnetic one which we actually experience in everyday lives - from being 'zapped' in the dry winter weather when you walk across the carpet and then touch something metal, to lightning, to your mobile phone, to seeing light and to the very monitor on which you are reading these lines. Since this is the strongest force that actually touches our lives, physicists usually assign the strength of 1 when they talk about relative strengths of all four interactions. On this scale the previously mentioned strong nuclear force would be 100, or one hundred times stronger than the electromagnetic. The electromagnetic interaction is mediated by photons.

Then comes the Weak Nuclear which like the strong nuclear acts only at small ranges (at about 1 am - 1 atto meter = 10-18m). This interaction is also about 1010 times weaker than the electromagnetic and is responsible for the beta decay of particles and nuclei. Weak nuclear interaction is mediated by the exchange of so called intermediate vector bosons (W+, Z0, W-)

Gravitational interaction is the weakest of the four. In fact gravitational interaction is about 1040 times weaker than the electromagnetic. Are you surprised? Well, this disagreement between our perception and the actual strength of the forces is due to the fact that gravity fills our lives on a minute to minute basis and that it is an always attractive force (as compared to the electromagnetic which can be attractive and repulsive - and therefore cancels itself often.) Gravitational interaction is mediated by gravitons - which are the only interaction carrier particles that have not been discovered to date.
Answered by: Anton Skorucak, M.S. Physics, Creator

Science Quote

'Our job in physics is to see things simply, to understand a great many complicated phenomena, in terms of a few simple principles.'

Steven Weinberg

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