Ascientist develops a new experiment to test atomic theory. his results do not agree with the theory. what will most likely happen next?
scientists worldwide will reject atomic theory because of the new results.
the scientist will change his results to agree with the accepted theory.
other scientists will reject the results because they do not agree with the theory.
the scientist will repeat the experiment to make sure that his results are reliable.

The scientist will repeat the experiment to make sure that
his results are reliable.

His results are pretty serious. Before he publishes anything
to describe his experiment and results, he has to be pretty
durn positive that he's actually seeing what he thinks he is. 

He will repeat his experiment once, twice, maybe twenty times.
He will try to find some other ways to test the theory ... maybe
ways that are more sensitive to the particular characteristic that
he believes is showing an unexpected result.  Each time, he will
closely and carefully examine the machinery and the set-up of his
experiment, particularly the parts where the machinery itself could
produce the effect he thinks he is seeing. 

He will read, and he will have everyone on his team read.  Together,
they will find and read everything they can get their hands on that
describes where the existing theory came from, the observations
that led others to propose the theory as it stands, and the experiments
that were done to test it.

When he is convinced that his result is accurate and reliable, and
that it contradicts the existing theory, he'll go public, and publish
the complete description of his experiment and his results.

When his publication gets around to everyone, then ...

1).  The first thing everyone else will do is try to find weaknesses or
mistakes in his experiment, or in the results he concluded from it.
Anybody who finds a simple or obvious problem with his work wil
publish THEIR thoughts for everyone to see.
If no serious or simple problems are found, and there's a possibility
that he may be right, then ...

2).  OTHER scientists will repeat the first scientist's experiment, OR
design a new experiment that drills down and focuses in on exactly
the part of the result that threatens the existing theory.
When THEY have results that they're sure of, then THEY'll publish
THEIR results around the world, and THEIR work will go through
the same examination that the first one did.

Gradually, maybe over a period of years, a sense of confidence
will build up among several scientists ... maybe not all of them ...
and the existing theory will change to fit the new results.