I can only think of the other things science has said were impossible.
Five hundred years ago science knew the world was flat.
Aristotle (384 – 322 BC) thought earth was round. And he used the shadow of Earth and differences in night sky stars visible from Athens and from Egypt as proof to that.
Of course, Erastothenes of Alexandria (276 BC - 194 BC) actually measured how big the Earth was. He also developed latitude/longitude coordinate system...
And contrary to popular beliefs, people in middle ages didn't actually believe that earth was flat. Most likely normal people never even thought of it, so they didn't believe in either flat or round... But sailors at least knew the earth was round, and so did scholars.
Three hundred years ago science knew the Earth was the center of the solor system.
Considering that Newton published his
Philosophiae Naturalis Principia Mathematica July 5, 1687 (and that was 319 years ago), I'd say that there were no real scientists 300 years ago that STILL did prefer the geocentric model of universe. People, yes, but no scientists.
What you refer to was not science but dogmatic view of nature preferred by religious authorities.
However, it is true that modern day physics is in quite essentially in same state as it was before quantum mechanics and relativity principle were introduced... in 19th century and early 20th, many scientists really thought that most natural phenomena had already been explained and the classical physics, coupled with Maxwell's electromagnetics, was the key to understanding everything in nature, and only minor details needed clarification.
Those minor details were really minuscule - but they had a profound effect in physics. After Planck's and Einstein's presentations of what's actually going on in electrodynamics really expanded the physical knowledge, and that expansion has been continuing until present day...
Today, we again seem to think that we know most things, and just a few things are in need of a finalizing, great unification, and then all the physics can be summed together into one Grand Unified Theory.
Anyway, one thing is sure - no device produces energy of *nothing*. It comes from something. We may not know what causes it, but something does, and some day we'll find out how it happens.
That's assuming that this news is not just another flase alarm. There has been numerous quite similar news, and nothing has ever been heard of them later. And don't you dar even look at the door that reads CONSPIRACY with big, red letters. We don't need any (more) theories explaining how oil companies silently get rid of the energy machines that could threaten their business...

EDIT: One more thing, quote from th eopening message's link:
"Such devices directly violate the most fundamental laws of nature, laws that have guided the scientific progress that is transforming our world."
Devices
can't violate laws of nature.
They can seemingly work in a way that is in controversy with
human knowledge of laws of nature, but that's no reason to say the devices themselves violate laws of physics.

If something happens, it happens, no matter how impossible it might look like. If this device indeed produces energy, that energy comes from something, and it's up to scientists to research the phenomenon and define the mechanisms behind it.