James' World 2

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For as long as humans have roamed the Earth, we have sought to find our place in the cosmos. From the city-states of ancient Greece to the soaring capstones of the Egyptian pyramids, across the deserts and towering mountains of ancient China down to the rolling plains of Mesoamerica, humans have sought to understand how the universe works. They developed mathematics to trace the motions of the planets, estimated the circumference of the Earth by walking from city to city, created star tables and timekeeping codices, and even recorded celestial events like Halley’s Comet, supernovae, and eclipses. 

With time, we have refined our models of the Universe. Using ellipses, Johannes Kepler reconfigured celestial motions. Galileo revolutionized Copernicus’ heliocentric model of the Solar System by discovering that the Sun, not the Earth, is the body around which all other elements of the Solar System orbit. Isaac Newton developed the theory of gravity, which was later supplanted by Albert Einstein’s theory of general relativity.

Discovery by discovery, we paint in the gaps of the picture of our Universe; and yet somehow, with each brushstroke, that image morphs, evolving into something ever-changing, new, and unrecognizable. The Universe that Kepler and Galileo, Copernicus and Kepler, Newton, and Galileo, and even Einstein understood is different from the one we know today.

Today’s understanding of the Universe is unsettling. It is not one that fits in a tidy little box with neat lines and a perfect lid. Our Universe is mystifying, complex. It defies expectations. 

For starters, our Universe is not a static, enclosed entity. Our Universe is expanding. From everywhere all at once, the fabric of spacetime is stretching away from everywhere else like an inflating balloon, carrying galaxies along with it. Photons traveling the lanes of the cosmos are stretched along with spacetime, their wavelengths growing ever longer, or redder, thus red-shifting with the expansion of space. 

Our Universe isn’t expanding into anything. To our knowledge, there is no extra dimension around the Universe; rather, space itself is expanding, causing the space between galaxy clusters — the largest gravitationally bound objects in the Universe — to get bigger and bigger with time.

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Credit: ESA/Hubble

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