Einstein's Effort Toward Unification of Forces
Since it appears that all known interactions between objects can be described with only four fundamental forces, it is tempting to ask "If only four, then why not only one?" Perhaps all interactions between matter can be described in terms of one master force. The quest for unification of forces is indeed an intriguing one. It captured the imagination of Einstein and he pondered it for some years.
Since the electromagnetic and gravity forces are both infinite in range and obey the inverse square law, looking first for the unification of those forces makes perfect sense from the outset. They have exactly the same mathematical form. Einstein spent time trying to show that under the appropriate conditions, they could be described as a unified single force. Despite the similarities in form, we now know that the gravity force will be the last to yield to unification and that the more implausible unification of the electromagnetic and weak forces was the first step. With the discovery of the W and Z particles, the intermediate vector bosons,
in 1983 it was being asserted that the experimental evidence was consistent with electroweak unification.