This is a meaningless argument people trot out all the time for things they just don't understand. Sometimes it applies but often it doesn't.
For example, people will dismiss arguments saying FTL is likely impossible because people once said that about going to the Moon. To be fair, there was some logic to the anti-Moon argument based on physics. The big change came with multi-stage rockets that solved the weight and thrust problems. And even then it's close [1].
There are good, physical reasons why FTL is highly likely impossible. You know, based on phnysics.
Likewise, the challenges to commercial fusion are also based on physics. Fusion reactions produce neutrons. Neutrons can't be magnetically contained. Neutrons destroy the container and, more importantly, lose energy from the system.
For example, people will dismiss arguments saying FTL is likely impossible because people once said that about going to the Moon. To be fair, there was some logic to the anti-Moon argument based on physics. The big change came with multi-stage rockets that solved the weight and thrust problems. And even then it's close [1].
There are good, physical reasons why FTL is highly likely impossible. You know, based on phnysics.
Likewise, the challenges to commercial fusion are also based on physics. Fusion reactions produce neutrons. Neutrons can't be magnetically contained. Neutrons destroy the container and, more importantly, lose energy from the system.
But saying "people once said the Earth was flat" or "people once said we couldn't get to the Moon" and so on are just meaningless platitudes. [1]: https://www.realclearscience.com/blog/2017/07/06/if_earth_wa...