I always wonder about how physicists "know" how old our universe is and how far away are other things in the universe and how many galaxies there are and are there really parallel universes and multiple dimensions?
How do they KNOW?
Same with homo sapiens' extinction. Ever wonder about it or ponder upon it?
It is estimated that 99.9 percent of species that ever lived are extinct. HOW DO THEY KNOW HOW MANY THAT IS/WAS?
Homo Sapiens are about 300,000 years old and are the last of its kind. There were NEANDERTHALS and HOMO ERECTUS and DENISOVANS and AUSTRALOPITHICUS. All gone. All extinct.
It is further estimated that there is a 95% likelihood that we will be dead and gone somewhere between 5,700 and 7.8 million years from now. A very large window.
The Copernican Principle is that the earth is not the center of the universe. And homo saps do not occupy a special position in space.
There is a DOOMSDAY ARGUMENT. Philosopher John Leslie estimates that before we are extinct there will have been 1.2 trillion of us...all the people who will ever have been born. So far it is estimated that number is about 100 billion born so far. It is estimated that we will become extinct in about 9000 years.
How do they KNOW? How can they KNOW?
