One in 200 stars has habitable Earth-like planets surrounding it - in the galaxy, half a billion stars have Earth-like planets going around them - that's huge, half a billion. So when we look at the night sky, it makes sense that someone is looking back at us.

However, one new theory says that dark matter may be ordinary matter in a parallel universe. If a galaxy is hovering above in another dimension, we would not be able to see it. It would be invisible, yet we would feel its gravity. Hence, it might explain dark matter.

If you could meet your grandkids as elderly citizens in the year 2100 … you would view them as being, basically, Greek gods… that's where we're headed.

The energy necessary to create a wormhole or to wrap time into nuts is incredible. It's not for us. It's maybe for our descendants who have mastered the energy of this technology. So if one day, somebody knocks on your door and claims to be your great great great great granddaughter, don't slam the door.

I am a figure skater, which helps me appreciate Newton's theory of mechanics.

I agree, along with Carl Sagan, that we should eventually become a two planet species. Life is too precious to place on a single planet.

...the laws of physics, carefully constructed after thousands of years of experimentation, are nothing but the laws of harmony one can write down for strings and membranes. The laws of chemistry are the melodies that one can play on these strings. the universe is a symphony of strings. And the "Mind of God," which Einstein wrote eloquently about, is cosmic music resonating throughout hyperspace.