Gravity

Category archives for Gravity

“There is no such thing as perpetual tranquillity of mind while we live here; because life itself is but motion, and can never be without desire, nor without fear, no more than without sense.” -Thomas Hobbes It’s hard to believe, but despite being at rest here on the surface of Earth, we’re actually hurtling through…

“If you’re puzzled by what dark energy is, you’re in good company.” -Saul Perlmutter We normally assume that the fundamental constants of the Universe are actually constant, but they don’t have to be that way. They could vary in space, in time, or with the energy density of the Universe, in principle. Before believing in…

“If something doesn’t reach you on a personal level, let it go. It’s hard enough dealing with everything that does.” -Judi Culbertson There are two types of electric charge: positive and negative. Like charges repel; opposite charges attract. In gravitation, though, there’s only one kind of gravitational charge, more commonly known as mass. And everything…

“If you haven’t found something strange during the day, it hasn’t been much of a day.” -John Archibald Wheeler Today, we take the existence of gravitational waves for granted. They were predicted by Einstein almost immediately following the first publication of general relativity, they were indirectly detected decades ago and they’ve been directly detected multiple…

“In our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, as far as possible, relations between the manifold aspects of our experience.” -Niels Bohr When it comes to galaxies, clusters of galaxies or the largest-scales on the Universe, dark matter is absolutely required.…

“It’s the gravity that shapes the large scale structure of the universe, even though it is the weakest of four categories of forces.” -Stephen Hawking Galaxies don’t just exist in isolation in our Universe, but are often found bound together as a part of even grander structures. Our own Milky Way is bound in a…

How flat can a planet be? (Synopsis)

“‘I’ll follow him to the ends of the earth,’ she sobbed. Yes, darling. But the earth doesn’t have any ends.” -Tom Robbins We have some pretty good definitions of what it takes to be a planet, and one part of that definition is that a world needs to be massive enough to pull itself into…

“For the first time, astronomers have outlined and named the network of galaxies that includes the Milky Way, adding a line to our cosmic address and further defining our place in the universe.” -Douglas Quenqua There’s been a longstanding puzzle in astrophysics that’s finally coming to a head. For nearly a century, we’ve known that…

Ask Ethan: What Is Spacetime? (Synopsis)

“‘Space-time’ – that hideous hybrid whose very hyphen looks phoney.” -Vladimir Nabokov Sure, you know what space and time are. If you heard of Einstein and relativity, you might know that they’re not absolute quantities, but that how you experience distances and the ticking of clocks is dependent on your motion through the Universe. But…

“Work gives you meaning and purpose and life is empty without it.” -Stephen Hawking Throw a book into a black hole, and the information must somehow wind up inside. Same goes for a star, a planet, or even a single proton: that information must be maintained. But allow enough time to pass, and quantum theory…