Correct. There's also logic and theoretical physics. Why do you think Hawking didn't accept his own theory about Multiverses?
I don't know. Is it important?
Einstein didn't believe his predictions about black holes etc. So what?
Do you think Earth is the only planet in the Universe with life on it? Why? Why not?
I think it is highly doubtfull that earth is the only planet with life on it. A couple of reasons for that, which all taken together, I'ld rate it quite likely that there is life elsewhere, somewhere, at some time.
In no particular order:
- We've only been really looking for a couple decades and covered not even a pixel of our own galactic backyard, yet already we discovered dozens, hundreds of rocky planets orbitting in the goldilock zone (meaning, correct environment for liquid water - a prerequisite for life as we know it).
- There are some 100 billion stars in a galaxy, each with potentially multiple planets orbitting them
- There are some 200 billion galaxies in the observable universe. That's a LOT of planets
- Life as we know it, is made up from the most common elements in the universe. In fact, the ration at which elements appear in our bodies, pretty much match the universe one for one in terms of "availability". This essentially means that we are made from the
most common stuff in the universe.
- We are carbon based, which in itself is not that hard to make. Carbon is so chemically rich that you can make more molecules out of carbon then all other elements combined.
In short, given the extreme vastness of the universe + the fact that while we like to think we are special, we are actually made from the most common stuff in the universe (found everywhere, throughout the universe), coupled with the realisation that earth (in terms of materials and orbital path) isn't that special either....
Yeah, I'ld say it's quite likely that there is life on other planets in the vast universe.