It has been suggested that an advanced civilization might have the technology to warp spacetime so that closed timelike curves would appear, allowing travel into the past. This paper examines this possibility in the case that the causality violations appear in a finite region of spacetime without curvature singularities. There will be a Cauchy horizon that is compactly generated and that in general contains one or more closed null geodesics which will be incomplete. One can define geometrical quantities that measure the Lorentz boost and area increase on going round these closed null geodesics. If the causality violation developed from a noncompact initial surface, the averaged weak energy condition must be violated on the Cauchy horizon. This shows that one cannot create closed timelike curves with finite lengths of cosmic string.

Pulling up to a house in the suburbs of Boulder, Colorado, the white van seems unremarkable — almost nondescript, save for a few institutional decals. But when the door slides open, it reveals an unusual scene: the standard benches have been tossed out, traded for retractable tables, an examination chair, and a psychedelic wall rug (to mellow the vibe).

🚘😏Roads?

☝️😉Where we’re going we don’t NEED roads!

ALI technologies’ president said the XTURISMO, which can reach a top speed of 80km/h, would prove popular in the Middle East.

In 2006, when Tomás Palacios completed his PhD in electrical and computer engineering at the University of California at Santa Barbara, he was torn between taking a job in academia or industry.

“I wanted to make sure that the new ideas that we were generating could find a path toward society,” says Palacios, the newly tenured Emmanuel E. Landsman Associate Professor of Electrical Engineering and Computer Science at MIT. “In industry, I was sure that would happen; I was not sure how it would work in academia.”

YouTuber The Action Lab is a prolific science expert who has brought us many cool videos such as this one where he made a laser microscope using just a drop of water or this one where he made a black mirror. Now, he is back with an interesting and entertaining video where he explains how shifty or color-changing glass works.

He starts by showing us examples of three types of this glass. He takes light yellow, dark yellow, and blue pieces of glass and he changes his lightbulb from a halogen one to a compact fluorescent one.

Immediately, the pieces of glass turn pink, orange, and violet. How does such an extreme change occur?

The system tables in each Microsoft SQL Server database contain metadata that can help you understand the database.

A new study published last week in arXiv reports that researchers found an unidentified object nearly 13.5 billion light-years away in the universe.

Mangetoreception, or the ability to sense Earth’s magnetic field, is basically a superpower.

Just as the ancient Minoans of Crete used the stars for maritime navigation, birds today migrate with the help of Earth’s magnetic field.

Bar-tailed Godwits—famous for their longest-known non-stop migration journeys—use the magnetic field to help them figure out their current positioning in addition to where they should head next. And although this isn’t the first time scientists have looked at mangetoreception (also called magnetoception) in birds, we still don’t have a clear understanding of how these animals are able to tap into the magnetic field and make use of it.