I had a friend years ago do a whole stand-up routine about sub-atomic particles, quarks, quantum strangeness, and tachyons.
So, so, ...tacky...
Then the mainstream decided they didn't and couldn't exist, because ...Einstein.
Then a few courageous researchers and mathematicians pointed out they absolutely did, because they HAD to exist, because...the math.
So I guess they're just like dark matter...
And then there's stuff like what the MFMP is involved with (yes, here on STEEMIT)
https://steemit.com/science/@mfmp/ecco-looking-for-tachyons-with-laser-microscopy#comments