Originally posted by Grampy Bobby
One Simple Question
Based upon your knowledge or opinion are there are things within the universe that we're unable to see which actually exist?
Simple answer: of course, and everybody knows this to be true.
But lets dig a little deeper. Lets ask 'are there things within the universe we can know about that we're unable to see?'.
Now we must ask: what do you mean by 'see'? Do you mean 'light from the object must physical be absorbed by cells in your eyes'?
If so, then many many things quite obviously fall into this category even the plumbing under Bills house.
I much better definition however would be 'something that we can detect via experiment', in which case even dark matter is not ruled out - although it remains the case that the plumbing under Bills house is not known about via this means.
However, the plumbing under Bills house is not immune from such experimentation, so we can't really say 'we are unable to see it' merely 'we haven't seen it'.
In astronomy everything we see is in fact the past. So we can not actually see most of the universe as it is right now. For nearby places we can just wait, but to see what is happening right now in a galaxy 1 billion light years away would require us to wait at least another billion years. I think we can safely say that there are things going on including new stars in that galaxy that we are unable to see or detect by any means.
However, this all gets a bit complicated because another way of looking at it is to say it doesn't actually exist until it is at least theoretically detectable. That is roughly how quantum mechanics works.