universe Quotes

'What was there before the Big Bang?' That's a question that both kids and adults love to pose to anyone who seems sympathetic. After all, if the universe has only been around for roughly 14 billion years, isn't it legitimate to ask what was in existence before the mother-of-all-events cranked up the cosmos?

On Mars, where the air is spare - a hundred times less dense than on Earth - someone could hear you scream. But you'd have to really strain to get anyone's attention. On the Red Planet, where the wind is high-pitched and faint, even a symphony orchestra will sound as thin as cheap gruel.

A century ago, scientists believed there was only one obvious stomping ground for alien biology in our solar system: Mars. Because it was reminiscent of Earth, Mars was assumed to be chock-a-block with animate beings, and its putative inhabitants got a lot of column inches and screen time.

Give consideration to the fact that alien astronomers could have scrutinized Earth for more than 4 billion years without detecting any radio signals, despite the fact that our world is the poster child for habitability.

We can never prove that we're alone in the universe. But the Allen Telescope Array could prove that we're not.

The strongest signals leaking off our planet are radar transmissions, not television or radio. The most powerful radars, such as the one mounted on the Arecibo telescope (used to study the ionosphere and map asteroids) could be detected with a similarly sized antenna at a distance of nearly 1,000 light-years.

Mars still remains the astrobiology community's number one choice for 'nearest rock with life,' but there are many researchers who argue that the moons of Jupiter are better bets. In particular, Europa, Ganymede, and Callisto are all thought to hide vast oceans of liquid water beneath their icy, outer skins.

If this is the only planet on which not only life, but intelligent life, has arisen, that would be very unusual.

The usual metric for whether a planet is habitable or not is to ascertain whether liquid water could exist on its surface. Most worlds will either be too cold, too hot or of a type (like Jupiter) that may have no solid surface and be swaddled in noxious gases.

The Moon is a ball of left-over debris from a cosmic collision that took place more than four billion years ago. A Mars-sized asteroid - one of the countless planetesimals that were frantically churning our solar system into existence - hit the infant Earth, bequeathing it a very large natural satellite.