Skip to main content
Expert Voices

What's the most amazing thing about the universe?

Observations made with the European Southern Observatory’s Very Large Telescope in Chile have revealed for the first time that a star orbiting the supermassive black hole at the center of the Milky Way moves just as predicted by Einstein's theory of general relativity. Its orbit is shaped like a rosette and not like an ellipse as predicted by Newton's theory of gravity. This effect, known as Schwarzschild precession, had never before been measured for a star around a supermassive black hole. This artist's impression illustrates the precession of the star's orbit, with the effect exaggerated for easier visualization.
Observations made with the European Southern Observatory’s Very Large Telescope in Chile have revealed for the first time that a star orbiting the supermassive black hole at the center of the Milky Way moves just as predicted by Einstein's theory of general relativity. Its orbit is shaped like a rosette and not like an ellipse as predicted by Newton's theory of gravity. This effect, known as Schwarzschild precession, had never before been measured for a star around a supermassive black hole. This artist's impression illustrates the precession of the star's orbit, with the effect exaggerated for easier visualization.
(Image: © ESO/L. Calçada)

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of "How to Die in Space." He contributed this article to Space.com's Expert Voices: Op-Ed & Insights

Perhaps the most powerful aspect of physics — and indeed perhaps the most amazing thing about the cosmos as a whole — is the universality of physical laws and theories. 

A few scant equations — small enough to fit on your favorite T-shirt — can explain a variety of phenomena from one edge of the universe to the other, and from the earliest moments of the Big Bang to the unfathomable future. Let's get a taste for just how powerful modern physics can be.

Related: The universe: Big Bang to now in 10 easy steps

Games of gravity

Albert Einstein's general theory of relativity is our modern theory of how gravity works: matter and energy bend space-time, and in turn the bending of space-time tells matter how to move. The math is a bit complex: it takes a suite of 10 interrelated equations to describe all this bending and warping and moving. But those equations contain enormous power.

For example, in the limit of weak gravity, Einstein's equations reduce to the more familiar expressions of Newtonian gravity, which is used to explain everything from the trajectories of thrown baseballs to hydroelectric dams. Beyond the surface of the Earth, Einstein takes more control, where the equations of relativity are used to provide accurate positioning with the GPS system and precisely predict the orbits of all the planets.

Those very same equations, without a single modification, go on to greater feats, revealing the existence of black holes and their workings, the growth of the biggest structures in the universe, the presence of dark matter inside galaxies and the Big Bang itself.

All of that from a set of 10 equations, spanning both cosmic space and cosmic time — indeed, showing that the universe has a finite age in the first place.

Related: How old is the universe?

Nuclear energies

When physicists began to crack the nuclear code in the 1940s, they had no idea that their machinations would end of unlocking one of the most perplexing mysteries of astronomy: how stars work. Prior to this time, scientists had tried all sorts of attempts to reconcile the age of the Earth as revealed by geology and paleontology (billions of years) with all the known physical ways to keep the sun burning so brightly. These attempts, as a rule, failed quite miserably, with even the best explanations only reaching a few million years.

But nuclear physics was a whole new ball game, and once physicists figured out the conditions necessary to ignite nuclear fusion (namely, insanely high pressures, temperatures, and densities), they realized that such conditions aren't always human-made (inside nuclear bombs and reactors) but can be found in nature itself: in the hearts of stars.

Nuclear fusion of hydrogen is how stars power themselves for billions of years, and the equations that physicists use to understand that process are the exact same ones they use to turn nuclear reactions into usable energy. From the tiniest of atoms to the largest of stars, nuclear physics — a relative newcomer in the world of physics — unites the cosmos in a surprising way.

Laws of motion

But you don't have to use esoteric equations of relativity or complicated calculations of nuclear reactions to discover the universality of physics. It can be as simple and straightforward as, say, a car crash.

When two vehicles collide, the laws of conservation of energy and momentum apply: the total amount of energy and momentum before the collision must equal the total amount of energy and momentum after the collision. Using these simple statements, investigators can reconstruct the scene of the accident, figuring out which driver was at fault and what led to the collision.

And cars aren't the only thing in the universe that smash together.

Colliding stars. Merging galaxies. Mixing gas clouds. It's rare to find a paper in astronomy or physics that doesn't mention, in some way, the conservation of energy and momentum. Scientists use these principles to understand just about everything in the cosmos.

Why is that gas cloud radiating energy? Conservation of energy and momentum. Why is that neutron star changing its rotation speed? Conservation of energy and momentum.

What will happen when those galaxies collide? Conservation of energy and momentum.

The next time you get in a car accident, take a moment to think about momentum, and how it applies throughout the universe, wherever you are.

Learn more by listening to the episode 'What's the most amazing thing about the universe?" on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com. Thanks to @iva_987 for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

  • dfjchem721
    The most amazing thing is how much we do know about it, and how little that really is!

    But perhaps the most amazing thing about the universe is something we do not even know about, or could ever understand.
    Reply
  • TheMatrixDNA
    dfjchem721 said:
    But perhaps the most amazing thing about the universe is something we do not even know about, or could ever understand.
    Like the amazing result of my calculations: This Universe is like an egg, the galaxies are the cells of a placenta, inside it is occurring the embryogenesis of a unique universal system, which began after the Big Bang in shape of atoms, then evolved to shape of astronomic system, from here evolved into cell´s systems and today, here and now, it is in shape of human brain. So, in this Universe is occurring merely a genetic process of reproduction, of the thing that triggered the Big Bang as an event of fecundation. Why i like this theory? because it shows how the building block of our DNA has same shape of the building blocks of galaxies and atoms, so, DNA is a biological shape of a universal Matrix.
    But... which is the meaning of our existence? We are 8 billions half-conscious genes that - with more billions or trillions of brothers genes at other worlds - are building the last shape of this universal system, called consciousness. So, the amazing thing is the universal history: " From the Big Bang to the Big Birth! " We will see there! B.Y.O.C = Bring Your Own Champagne...
    Reply