To Infinity and Beyond by Neil DeGrasse Tyson & Lindsey Nyx Walker

Author:Neil DeGrasse Tyson & Lindsey Nyx Walker [Tyson, Neil DeGrasse & Walker, Lindsey Nyx]
Language: eng
Format: epub
Publisher: National Geographic
Published: 2023-09-12T00:00:00+00:00

INTO THIN AIR

“You’re not the same as you were before,” says the Mad Hatter in the Disney film Alice in Wonderland. “You were much more…muchier…you’ve lost your muchness.” In our attempts to define outer space, we sound like the Mad Hatter admonishing Alice for losing her muchness. We tend to define space not by what it is and has, but by what it is not and doesn’t have. It has fewer particles than Earth’s atmosphere. It has less pressure. It is an absence of heat, of light. It’s enticing to believe that by just venturing farther and farther from Earth, we will eventually arrive at a place of total emptiness, devoid of all things. We often think of space this way—as a dark abyss, as nothingness. But, no. Space is not nothing, and it’s far from empty, as we will discover in this section.

Often our declarations of what exists or does not exist derive from the five fallible senses with which we perceive the environment. Our imperfect sensory interface with the physical world limits our attempts to understand the universe every day. Everybody knows that air is thin; why else would we be impressed when a magician pulls a rabbit “out of thin air”? Yet a thimble-size container (one cubic centimeter) of pure, invisible, sea-level air contains more molecules (27 quintillion) than all the grains of sand on an average beach.

Is this a lot or a little? A rabbit that pops in and out of an otherwise empty magician’s hat may be interested to know that the average density of matter in the universe is much, much less than the air in that hat. But how much less?

Let’s upgrade our thimble-size container to a hot tub–size (35 cubic feet) birthday present with your name on it. If you unwrapped your gift only to find no objects inside, you would justifiably feel the giver was a bad friend for gifting you a big box full of nothing. But what your friend gave you was 2.7 x 1025 molecules of air. That’s 27 septillion molecules (27,000,000,000,000,000,000,000,000). You can’t fairly claim they gave you nothing when they gave you 27 septillion somethings. (Pocket this little fact for later, in case you ever forget a special someone’s birthday and find yourself in need of a quick present.)

The rarest, most mythical, most sought-after, and pondered-over gift in the universe would in fact be nothing—true nothing.

So, let’s say your friend now wants to make up for their lousy gift of 27 septillion molecules and is determined to give you the gift of true nothing. Might they have better luck finding it in outer space? If they could somehow obtain a one-cubic-meter sample of the space between planets, box it up, and bring it back to Earth, you might believe the box to be truly empty. Again, no. Inside that box (assuming it to be a magic box, impervious to the crushing differences in atmospheric pressure) would be perhaps five million somethings, mostly hydrogen and charged particles of solar wind.

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