It’s the same toy as before except now, there are two tubes to play with – and since it’s a bit like juggling, the gravity-defying effect can be virtually endless.
Each time you drop the metal ball through the tube you’d expect it to zip out the other end but instead, it lazily creeps from one end to the other and dribbles out into your waiting hand.
I can’t wait for the inevitable three-tube version to hit the market!
Gravitational waves are real, and scientists have detected them. In the video above, PBS Space Time explains the discovery by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO). From the New York Times:
A team of physicists who can now count themselves as astronomers announced on Thursday that they had heard and recorded the sound of two black holes colliding a billion light-years away, a fleeting chirp that fulfilled the last prophecy of Einstein’s general theory of relativity.
That faint rising tone, physicists say, is the first direct evidence of gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago (Listen to it here.). And it is a ringing (pun intended) confirmation of the nature of black holes, the bottomless gravitational pits from which not even light can escape, which were the most foreboding (and unwelcome) part of his theory.
More generally, it means that scientists have finally tapped into the deepest register of physical reality, where the weirdest and wildest implications of Einstein’s universe become manifest.
Below, NASA's animated simulation of the black holes merging and releasing the gravitational radiation (background here):
above image credits: R. Hurt/Caltech-JPL Read the rest
Gravity isn't uniform. Denser planets and objects in space — that is, things with more mass to them — experience a stronger pull of gravity. But even if you zoom in to the level of a single planet (or, in this case, our Moon), gravity isn't uniform all the way around. That's because the mass of the Moon isn't uniform, either. It varies, along with the topography. In some places, the Moon's crust is thicker. Those places have more mass, and thus, more gravitational pull.
This map, showing changes in density and gravity across the surface of the Moon, was made from data collected by Ebb and Flow — a matched set of NASA probes that mapped the Moon's gravitational field before being intentionally crashed on its surface last December. By measuring the gravitational field, these probes told us a lot about how the density of the Moon varies which, in turn, tells us a lot about topography.