We have built systems that have detected:

• Black holes which collided 2000000000 lightyears away
• single photons
• neutrinos, particles that can pass through lightyears of lead
• concentrations of chemicals rated in picograms (0.000000000001g) per litre
• vibrations rated at 1/1000000 of a g

We have come into a world where people carry around, nearly 24/7, devices capable of recording high definition video, measuring variances in light, magnetism, vibration, storing time correlated data and even processing over it with enough proficiency to put digital bunny ears or makeup on you in real time.

Despite all this, we have no evidence and no mechanism by which we even might expect ghosts could exist. It’s reasonable to say you can’t be 100% certain they don’t exist, but it is also wildly unreasonable to say they do.