I remember reading a short story (or short book?) that was at first set around the 1930s (maybe?) and an experiment goes wrong creating a very fine beam which increased in width the further out it got from its source. Whatever was hit by this beam was transported into the distant future. This included a man (the protagonist) who finds himself on Earth but an indeterminate time in the future where he has to relearn the language and reconnect with this future humanity. He's viewed as an oddity as he still has bodily hair so they permanently remove his beard. It feels like an Asimov era story. Can anyone help with this?
Pebble in the Sky, by Isaac Asimov (as you thought). Published as a full novel in 1950. The Wikipedia entry (I linked it to the title) tells me something I either had not known, or had forgotten: The first draft, titled "Grow Old with Me," was about 40,000 words, but when Asimov couldn't find a magazine editor who wanted to publish it, he agreed with a Doubleday editor's suggestion that he expand the idea to 70,000 words for publication in book format. (And change the title.) Wikipedia also says the first draft was written in the summer of 1947, and that this shorter version was eventually printed in the book The Alternate Asimovs in 1986. Possibly you've read that book?
I have read the full-length novel at least three or four times. It begins just as you describe. Something peculiar happens in a research lab, and a very small series of holes are drilled through the walls, as if an incredibly powerful beam (similar to a laser, which had not yet been invented in real life) had suddenly burned right through everything that got in its way. One of the scientists calculates that the beam was widening as it moved away from the source, and he watches the newspapers for the next few days, wondering if he will see a report of someone screaming that a man (or half of a man?) had suddenly vanished into thin air, somewhere a few miles away from the lab. He sees no such report, and relaxes -- not knowing that it did happen that a grown man was caught by the beam, except no one else happened to observe and report it.
Here's an excerpt from the Wikipedia entry. It goes pretty well with the other stuff you remembered about what happens to this man who suddenly finds himself in the far future.
While walking down the street in Chicago, Joseph Schwartz, a retired tailor, is the unwitting victim of a nearby nuclear laboratory accident, by means of which he is instantaneously transported tens of thousands of years into the future (50,000 years, by one character's estimate, a figure later retconned by future Asimov works as a "mistake"). He finds himself in a place he does not recognize, and due to apparent changes in the spoken language that far into the future, he is unable to communicate with anyone. He wanders into a farm, and is taken in by the couple that lives there. They mistake him for a mentally deficient person, and they secretly offer him as a subject for an experimental procedure to increase his mental abilities. The procedure, which has killed several subjects, works in his case, and he finds that he can quickly learn to speak the current lingua franca. He also slowly realizes that the procedure has given him strong telepathic abilities, including the ability to project his thoughts to the point of killing or injuring a person.