A new technique has measured the lowest temperature ever recorded for liquid water. [Physics] Published Tue Jan 02, 2018

Introduction There are a number of posts on PF involving a general confusion over the multi-vairiable chain rule. The problem is often caused by a lack of clarity about the roles of functions and variables and what precisely each derivative means. This insight is an attempt to clarify things. Part A: The Single-Variable Chain Rule […]

There is remarkable biodiversity in all but the most extreme ecosystems on Earth. When many species are competing for the same finite resource, a theory called competitive exclusion suggests one species will outperform the others and drive them to extinction, limiting biodiversity. Show More Summary

Timpone made the leap from teaching to a life at Fermilab.

Conference: 25 Jul 2018 - 27 Jul 2018, Mieres, Oviedo, Spain, Spain. Organized by Polytechnic School of Mieres.

Low viscosity layer enables plate tectonics, but its cause remains unconfirmed

A Short Proof of Birkoff’s Theorem derived the Schwarzschild metric in units of ##G = c = 1##: \begin{equation} ds^2 = -\left(1 – \frac{2M}{r}\right)dt^2 + \left(1 – \frac{2M}{r}\right)^{-1}dr^2 + r^2d\theta^2 + r^2 \sin^2\theta d\phi^2...Show More Summary

Metalenses—flat surfaces that use nanostructures to focus light—promise to revolutionize optics by replacing the bulky, curved lenses currently used in optical devices with a simple, flat surface. But, these metalenses have remained limited in the spectrum of light they can focus well. Show More Summary

There's no physics linkfest this week, if only because so little happens (apart from year-end lists) in science news in the interval between Christmas and New Year's. But we'll be back next week. Meanwhile, here are Caliban (tuxedo) and Ariel...

Civil discussion and debate is critical to Physics Forums. But it is also important in everyday life. When arguments get overheated, people may avoid engaging with friends and family and the relationships could wither and die. If the only safe topic you can discuss with your friend is weather, your relationship is in danger. So, […]

Pop! goes the New Year's corks—and the bubbles that result might point to how high-quality your champagne is, researchers say.

Author(s): Philip Ball A passing gravitational wave produces shifts in the apparent positions of the stars, and these motions should be detectable with the Gaia space telescope. [Physics 10, 138] Published Fri Dec 29, 2017

Author(s): Eli Barkai and Yuval Garini The 3D motion of molecules at a solid-liquid interface is directly imaged for the first time. [Physics 10, 139] Published Fri Dec 29, 2017

A Short Proof of Birkoff’s Theorem derived the Schwarzschild metric in units of ##G = c = 1##: \begin{equation} ds^2 = -\left(1 – \frac{2M}{r}\right)dt^2 + \left(1 – \frac{2M}{r}\right)^{-1}dr^2 + r^2d\theta^2 + r^2 \sin^2\theta d\phi^2...Show More Summary

Every Christmas I try to do some sort of project. Something new. Sometimes it turns into something real, and last for years. Sometimes it goes no where. Normally, I have an idea of what I’m going to attempt – usually it has been bugging me for months and I can’t wait till break to get […]

A new method groups photons based on the radial component of their angular momentum. [Physics] Published Thu Dec 28, 2017

The following is one chapter in a series of Mathematical Quantum Field Theory. The previous chapter is 11. Reduced phase space. The next chapter is 13. Quantization. 12. Gauge fixing While in the previous chapter we had constructed the reduced phase space of a Lagrangian field theory, embodied by the local BV-BRST complex (example 11.21), […]

Cosmic analogue made by shaking ultracold gas

Highly efficient high power short pulse lasers at the wavelength range of 2 µm based on Tm3+ doped materials have a variety of applications such as material processing, LiDAR, mid-infrared OPOs for wavelengths up to 12 ?m, or mid-infrared supercontinuum generation. They also would enable direct coherent soft X-ray generation by high order harmonics generation.

A Global Positioning System (GPS) device gives your precise location by receiving light pulses from satellites with synchronized clocks then triangulating your location based on that information [1]. Since light travels at 300 million meters per second, your location will be off by about 1 meter if the clock times are off by only 3 […]

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