Thinking About the Universe
Maybe Newtonian physics doesn’t need dark matter to work.
“There are no ‘dark matter people’ and ‘MOND people,’ ” his colleague retorted.
“I am ‘MOND people,’” Milgrom proudly proclaimed, referring to Modified Newtonian Dynamics, his theory that fixes Newtonian physics instead of postulating the existence of dark matter and dark energy—two things that, according to the standard model of cosmology, constitute 95.1 percent of the total mass-energy content of the universe.
In our terrestrial view of things, the speed of light seems incredibly fast. But as soon as you view it against the vast distances of the universe, it’s unfortunately very slow. This animation illustrates, in realtime, the journey of a photon of light emitted from the surface of the sun and traveling across a portion of the solar system, from a human perspective.
Now you don’t have to fall into a black hole!
THE “POTSDAM GRAVITY POTATO” SHOWS VARIATIONS IN EARTH’S GRAVITY
People tend to think of gravity here on Earth as a uniform and consistent thing. Stand anywhere on the globe, at any time of year, and you’ll feel the same downward pull of a single G. But in fact, Earth’s gravitational field is subject to variations that occur over time. This is due to a combination of factors, such as the uneven distributions of mass in the oceans, continents, and deep interior, as well as climate-related variables like the water balance of continents, and the melting or growing of glaciers.
CARLO ROVELLI remembers the first time he glimpsed the beauty of Einstein’s theory of general relativity. He was an undergraduate lounging on a beach in southern Italy, leafing through a rodent-nibbled textbook. “Every so often I would raise my eyes from the book and look at the glittering sea: it seemed to me that I was actually seeing the curvature of space and time.”
On Thursday (Feb. 11) at 10:30 a.m. ET, the National Science Foundation will gather scientists from Caltech, MIT and the LIGO Scientific Collaboration in Washington D.C. to update the scientific community on the efforts being made by the Laser Interferometer Gravitational-wave Observatory (LIGO) to detect gravitational waves.
In the wake of some very specific rumors focused on the possible discovery of these elusive ripples in spacetime, hopes are high that the international LIGO collaboration of scientists will finally put an end to the fevered speculation and announce the discovery of gravitational waves.
Caltech’s Konstantin Batygin, an assistant professor of planetary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, discuss new research that provides evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system.
If life is effectively an endless series of photocopies, as DNA is transcribed and passed on from one being to the next, then evolution is the high-stakes game of waiting for the copier to get it wrong.
Too wrong, and you’ll live burdened by a maladaptive mutation or genetic disorder. Worse, you might never live at all.
But if the flaw is wrong in exactly the right way, the incredible can happen: disease resistance, sharper eyesight, swifter feet, big brains, better beaks for Darwin’s finches.
Stephen Hawking, Arthur C. Clarke and Carl Sagan (via satellite) discuss the Big Bang theory, God, our existence as well as the possibility of extraterrestrial life.
“Overture From Tannhauser” by London Symphony Orchestra With Wyn Morris ( • • )