New Clock May End Time As We Know It

“Our aim is that we’ll have a clock that, during the entire age of the universe, would not have lost a second.”

The world's most precise atomic clock is a mess to look at. But it can tick for billions of years without losing a second. (Credit: Ye group and Baxley/JILA/Flickr) — The world’s most precise atomic clock is a mess to look at. But it can tick for billions of years without losing a second. (Credit: Ye group and Baxley/JILA/Flickr)

Maybe its because we don’t understand time, that we keep trying to measure it more accurately. But that desire to pin down the elusive ticking of the clock may soon be the undoing of time as we know it: The next generation of clocks will not tell time in a way that most people understand. The new clock will keep perfect time for 5 billion years.

Strontium atoms floating in the center of this photo are the heart of the world's most precise clock. The clock is so exact that it can detect tiny shifts in the flow of time itself. (Credit: Ye group, Brad Baxley/JILA) — Strontium atoms floating in the center of this photo are the heart of the world’s most precise clock. The clock is so exact that it can detect tiny shifts in the flow of time itself. (Credit: Ye group, Brad Baxley/JILA)

“My own personal opinion is that time is a human construct,” says Tom O’Brian. O’Brian has thought a lot about this over the years. He is America’s official timekeeper at the National Institute of Standards and Technology in Boulder, Colorado.

To him, days, hours, minutes and seconds are a way for humanity to “put some order in this very fascinating and complex universe around us.”

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via npr

First Simulated Images of Two Black Holes Colliding

The equations of general relativity are so fiendish that nobody has been able to work out what a collision between two black holes would look like, until now… (PDF)

1*iAWwG2aymR3TmMH1fXpcfA — Lensing caused by various analytic spacetimes. For all panels, we use Figure 3 as a background, oriented such that the camera is pointed at the white reference dot. The camera has a 60 degree feld of view and is at a distance of 15 Schwarzschild radii from the origin measured using Kerr- Schild coordinates. The top row shows Minkowski and Schwarzschild spacetimes. The bottom row shows two views of the Kerr spacetime, with dimensionless spin x = 0.95, viewed with the camera pointing parallel to the spin axis of the black hole (bottom left) and perpendicular to the spin axis (bottom right). (Credit: A. Bohn, F. Hebert, W. Throwe, D. Bunadar, K. Henriksson, M. Scheel, N. Taylor)

The difficult part of this work is calculating the trajectory of the photons using the physics of general relativity. These equations are notoriously non-linear, so physicist sometimes simplify them by assuming that a system remains constant in the time it takes for light to pass by. The difficulty with black hole binaries is that this assumption does not hold— these objects orbit so rapidly as they approach each other that space-time warps, even during the time it takes for light to pass by.

A BBH system of equal-mass black holes with no spin, viewed near merger with the orbital angular momentum out of the page. (Credit: A. Bohn, F. Hebert, W. Throwe, D. Bunadar, K. Henriksson, M. Scheel, N. Taylor)

Andy Bohn(et al.) at Cornell University in Ithaca, New York, reveals how in-spiraling black hole pairs should distort the light field around them. The team has concluded that from large distances, binaries are more or less indistinguishable from single black holes. Only a relatively close observer would be able to see the fascinating detail that they have simulating or one with very high resolving power.

The first observation of much bigger deflections, such as those produced by black holes or black hole pairs, will be something of a triumph for whoever spots them first.

via physics arxiv