Featured Science Threads - Page 9

An understanding of Newton's laws is integral to the design and operation of the modern-day helicopter. The first modern-day helicopters came about in the 1940s so the laws were well known by then...but here's the thing. Newton published his laws in the Principia in 1687, but Leonardo Da Vinci had already invented the 'Aerial Screw'...

For years I have read and heard that the Solar System is there because of angular momentum issues. That is to say, the Sun itself can only rotate at some maximum rate in order to stay intact and the planets are there to equalise the angular momentum of the original nebula and produce a stable star. Well, that argument should apply...

A topic that continually comes up in discussions of quantum mechanics is the existence of many different interpretations. Not only are there different interpretations, but people often get quite emphatic about the one they favor, so that discussions of QM can easily turn into long arguments...

"It’s not a physical problem with the CPUs themselves, or a plain software bug you might find in an application like Word or Chrome. It’s in between, at the level of the processors’ “architectures,” the way all the millions of transistors and logic units work together to carry out instructions."

Although I'll (hopefully) be attending university next fall, I would love to cut my teeth on some STEM-related work before then. However, I don't know what kind of jobs are open to a high school student. I'm willing to consider volunteer work, as well...

Here is an NY Times article by Carl Zimmer, describing recent advances in predicting protein design.
This involves going from an amino acid sequence to a predict a protein 3D structure or going from what you want in a protein to the amino acid sequence that can generate it. This has long been a big computational problem....

A reference article to other articles on science facts that were discovered this year 2017. Some were theorized and finally proven, others were discovered totally by chance. Which ones most impressed you?

Your picture should show a physical phenomenon that visualises the solution to a mathematical problem encountered in the physical sciences. No equations in the pictures, but feel free to write down the corresponding equations in your submission post!

First of all I want to congratulate @Orodruin for his book publication! I myself thought that maybe someday, I would like to write a book. So I became a little bit curious about other titles that may have been written by Physicsforum members. I hear Benjamin Crowell is also a member physicsforums. What do you say?

At the time of writing this Insight, my textbook “Mathematical Methods for Physics and Engineering” just hit the virtual online shelves. This Insight will describe the process leading to its creation, from the first seeds of an idea to where we are today. Although each textbook has its own story, I hope this one can satisfy the curiosity of anyone who wonders how some textbooks come to be...

I've noticed that when I put a prefab meal in the microwave, the parts that are frozen over just don't defrost any time soon, even though the rest of the meal gets really hot. The reason is that the ice structure doesn't allow the polar water molecules to vibrate. My question: what can we do so that the ice does defrost - and quickly?

What should the Mathematics requirements for Physics degree really be? The usual official requirement is three semesters of Calculus, and then one more combination course which combines some linear algebra and not-too-complicated differential equations. Often the Physics majors, at least for bachelor's degree, take more than that and find some way of using some...

I'm reading this incredulous article where the new president of the Institution of Mechanical Engineers (which, I presume, is in the UK) is calling for universities in the UK to drop the requirement for Physics A-Level to encourage more women to enter the field of engineering. Her argument was that due to the "... initial male bias in physics lessons...", women are less inclined to take physics at the A-Level and thus, will not be able to pursue an engineering degree when they go to college...

Announcement! The discovery was made by researchers using machine learning from Google. Machine learning is an approach to artificial intelligence, and demonstrates new ways of analyzing Kepler data. Vanderburg works on various stuff, with a focus on more recent data (K2 mission). Jessie Dotson works on K2 data and seems to be a contact person for external users working with Kepler data...

I am not a very careful person and I am often overly ambitious. I often think of something that would be cool to have then try to design or build it without considering safety or my abilities. Do you guys know how I could train myself to not be overly ambitious and to be more careful?

I have always been on the skeptical, but not dismissive, end of judgments about achievemnts and rate of progress in this field. However, the following (please read through carefully) just completely blows my mind.
A self learning algorithm with no knowledge or base of games, starting only from the rules of chess, within 24 hours is much better than any other existing chess program despite running on hardware 900 times slower!

On November 15, 2017, LIGO Scientific Collaboration announced the observation of another binary black hole coalescence. The gravitational waves were observed by the twin LIGO detectors on June 8, 2017. This is the lightest black hole binary observed so far, with component masses 12 and 7 times the mass of the sun...

All life on Earth stores its genetic information in DNA using just four nucleotide letters: A, T, C, and G. Research published this week in the journal Nature describes how scientists engineered a bacterium to incorporate two new letters into their DNA (which they call X and Y, pictured below), and read those letters to introduce new amino acids into proteins...

Science Magazine is holding its annual vote for the people's choice for Breakthrough of the Year, which will accompany their own choice. Voting is open until Dec 3. You can vote here... What is your choice for the scientific breakthrough of 2017? Did the editors at Science not list your favorite scientific discovery?

"When it was first described in the 1920s by physicist Irvin Langmuir, plasma was said to be one of the fundamental states of matter, though not one that exists freely on Earth under normal circumstances. Plasma is made up of charged particles, ions and electrons, and does occur naturally as lightning; an occurrence that can be contained in man-made objects like florescent light bulbs and plasma-cutting torches..."

NASA announced in 2015 that they found some evidence for the existence of liquid water on Mars today - at least temporarily and underground. A new study comes to a different conclusion and proposes sand as origin of the observed material transport downhill. As interesting as these features are, the rovers on the ground stay away from them...

Here's a fun thing to do on a Sunday. I was thinking of all the everyday objects that I no longer need as much or as often because I carry a smart phone. Because I'm old, I may prefer the older way of doing things or maybe the old ways were superior. Nevertheless I need the old things less often and I certainly can't carry all of them around in my pocket.

I've been thinking about rolling motion, helped by @kuruman's excellent Insights article on the topic.
A crucial insight from that article is that, when a wheel rolls along a flat surface, its axis of rotation is through the instantaneous point of contact with the ground, not through its axle. Thinking about this, I reached a tentative conclusion that...

As a AI programmer, among other things, I know the limitations of the technology. So I vote No to this question. For one thing, safe driving demands being able to think ahead and anticipate situations which sensors do not pick up.

iPTF14hls was a supernova discovered in 2014. Typically they reach a brightness peak quickly and then fade over few months - but this star had several oscillations in brightness. To make it more confusing, archives from 1954 show a supernova at the same spot

CRISPR is often used to switch out a length of DNA for a different piece of sequence, which can change several base pairs at once. Here is a Science news report on how researchers have now developed methods to efficiently change single base pairs in a sequence (or single bases in single stranded RNAs)...

From what I understand, machine learning is incredibly good at making predictions from data in a very automated/algorithmic way. But for any inference that is going to deal with ideas of causality, it's primarily a subject matter concern, which relies on mostly on judgment calls and intuition. So basically, a machine learning algorithm would need human level intelligence and intuition to be able to do proper causal analysis?

Ed Witten posted an interesting article on arXiv a few days ago on the fate of global symmetries in physics beyond the Standard Model. In particular, Witten argues that the global symmetries of the Standard Model are all approximate and emergent at low-energy, and they should be violated at the GUT and Planck scales. In particular, a quantum gravity theory should only contain conservation laws associated with gauged interactions...

The first asteroid ever seen from another solar system is whizzing through our own, and astronomers are racing to observe the visitor before it slips away.

For those of you who work on their own vehicles, what has been your experience recently with aftermarket replacement parts? To me it seems the quality has gone down the tubes in general. Some of my experiences go back quite a few years (like 20) with solid state ignition modules. They might last several hundred miles...

As the title says, any ideas of great places that a physicist tourist could visit in US or UK?

To keep me busy on a Sunday I considered the "1-body radial movement in a (Newtonian) gravitational field problem". I was a bit surprised to find it quite hard finding decent explanations on it. My question is: does anyone have a reference of the explicit solution to the particle's position ##r(t)##? Let me show my calculation...

So, this has been bothering me for a few days and I'm having trouble understanding where the fault is. If we consider a uniform charge density ##\rho## extending through all space, then by symmetry, I would argue that ##\mathbf{E}=0## in all space. However, this does not agree with what a naive application of Gauss's Law would predict since ##\nabla\cdot\mathbf{E}=0\ne\rho/\epsilon##. So where exactly is the argument breaking down? Is there something unusual...

"Rumors are starting to fly that LIGO/VIRGO sees a signal of merging neutron stars, with an optical counterpart. Indeed, the thing that seems to have triggered the rumors was having a number of telescopes suddenly pointing at the same patch of sky. It's difficult to discuss the science behind the rumors pre-publication, but it might be reasonable to use this thread to discuss the science behind merging neutron stars."

Exam situations are always situations of stress. It comes with our endeavor to be as good as possible together with our fear to fail. Some students handle these situations better than others. But there are some tricks I encountered over the years tutoring young students. I’m sure everybody has developed their own ways to get along with tests, so the following has to be a personal view of mine. It resulted from my experiences...

"We present a list of open questions in mathematical physics. After a historical introduction, a number of problems in a variety of different fields are discussed, with the intention of giving an overall impression of the current status of mathematical physics, particularly in the topical fields of classical general relativity, cosmology and the quantum realm. This list is motivated by the recent article proposing 42 fundamental questions..."

"Three colleagues, Rainer Weiss, Barry C. Barish, and Kip S. Thorne, have won the 2017 Nobel Prize in physics, for their contributions to work that led to the observation of gravitational waves — something that happened for the first time in 2015." - NPR

This morning, the 2017 Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash and Michael W. Young for their discoveries of molecular mechanisms controlling the circadian rhythm. "Their discoveries explain how plants, animals and humans adapt their biological rhythm so that it is synchronized with the Earth's revolutions."

The Miami Herald posted this story. Built for bottleneck: Is Florida growing too fast to evacuate ... The article made a good point that I hadn't considered. A good evacuation plan does not require 10 million people to drive 600-1000 miles away. It means driving 10-20 miles inland to a shelter. In south Florida, 10-20 miles inland puts you in the Everglades or Big Cyprus Swamp. Those are really bad places to build 10000 shelter buildings...

The goal is to create the most beautiful or interesting equation aesthetically (pleasing to the eye).
This is not about it's mathematical significance. Get your inner designer on! Each member is allowed to post one equation. The equation can be completely made up...

This thread is for showing your images of solar activity taken with YOUR cameras, telescopes etc.
That is, don't post images from SDO, SOHO or any other professional sources unless you specifically want to ask "how do they do that and what are those solar features I can see? This is intended for those of you out there, like myself that get out there and do your own imaging and are looking for ways to improve...

Here is this week's advanced math problem of the week. We have several members who will check solutions, but we also welcome the community in general to step in. We also encourage finding different methods to the solution. If one has been found, see if there is another way. Occasionally there will be prizes for extraordinary or clever methods...

"For NASA’s Cassini orbiter—its fuel dwindling after 13 years exploring Saturn, along with the planet’s sprawling rings and dozens of icy moons—the end will come Friday at 7:55 A.M. Eastern time. That’s when mission planners project radio communications will be lost with the two-ton, bus-size spacecraft as it plunges into the giant planet’s turbulent atmosphere at more than 122,000 kilometers per hour." - sciam.com

This is the beginning of a series that gives an introduction to perturbative quantum field theory (pQFT) on Lorentzian spacetime backgrounds in its rigorous formulation as locally covariant perturbative algebraic quantum field theory. This includes the theories of quantum electrodynamics (QED), quantum chromodynamics (QCD), and perturbative quantum gravity (pQG) — hence the standard model of particle physics...

Again and again we hear of the consequences of loss of electrical power. Frequently, the authors call for more redundancies in the power grid so that blackouts will not happen. No complex system can ever be 100% reliable. However, as systems grow from very reliable to extremely reliable, people come to treat them as absolutely reliable. (A psychological quirk?) Lack of preparedness grows and the actual consequences become...

I just saw a double rainbow. On the brighter bow the color arcs were red on the left edge of the bow and shifted to blue on the right edge. On the dimmer bow the colors shifted from blue on the left edge to red on the right. Why were they separated oppositely like this?

I have heard about a moon Enceladus. Which is powered by tidal force. I suppose this force press back and forth on the moon and friction in the core causes heat. Can anyone explain it?

When sea waves approach the shore they roll up and break due to different velocities of water layers formed due to the gradual change in water depth. The highest wave peaks move faster than all other layers and thus falls down. All other layers fall the same way but in a delay. this ends up with wave rolling up when approaching the shore. Does light and sound wave have a similar phenomenon?

With LHC currently at 13TEV design energy, and a planned higher luminosity upgrade, is the current plan to double the magnet strength for the current existing LHC to arrive at a 28-33TEV collider, or is it building a completely new future 100 TEV collider near Geneva where LHC is housed but in a completely new tunnel or in China? Are future lepton collider plans, such as one in Japan, linear or circular?

This is an interesting question that popped through my mind. Some of us should know what is meant by „gauge transformations”, „gauge invariance/symmetry” and are used to seeing these terms whenever lectures on quantum field theory are read. But the electromagnetic field in vacuum (described in a specially relativistic fashion by the tensor...