Featured Science Threads - Page 6

Extend the following to a valid equation, using only mathematical symbols!

Example: ##1\; 2\; 3 \;=\; 1 \longrightarrow - (1 \cdot 2) + 3 = 1##. Solutions are of course not unique.

A new way to multiply one that only a computer could love if only it had enough bits to do it...

*Breaking Now* Media Advisory: Press Conference on First Result from the Event Horizon Telescope
April 10, 15:00 CEST (13:00 UTC. In 8 days and 13 hours)
Livestream links are on that website.

Two recent studies have found galaxies with little or no apparent dark matter, indicating modifying gravity can't work. Read more inside...

Perhaps this thread would be better located in the Earth forum (where hydrologists might more likely see it), but it is Mars not Earth. I recently read about a study on riverbeds (size, catchment size, meandering) on Mars that claimed large water flows in some riverbeds "late" in Mars history (post-dense atmosphere)...

Robert A. DePalma, a 37 year old curator of paleontology at the Palm Beach Museum of Natural History, in Florida, as well as a graduate student at the University of Kansas discovered and started mining a huge fossil deposit found in North Dakota...

No LHC this year (long shutdown), but Belle II at SuperKEKB started taking data a few days ago. Here is a press release. Belle II started last year with a low luminosity (low collision rate) - still good for detector calibration and so on. The goal for this year is to increase the luminosity and eventually collect enough data for interesting physics analyses.

I found these timelines on the Computer History Museum which are quite interesting to checkout... For me, it brought back memories of machines long past. They even mentioned the construction of my robot persona for the Forbidden Planet movie. Those were the days!

On the fraction of radiated power that lies to the left of the peak of the Planck blackbody function of spectral intensity vs. wavelength...

I'm wondering how and in what time frame new technologies emerged and found application in the history of science. I could make several examples of those which suddenly and unexpectedly changed the world, but not the vice-versa. In particular, I'm wondering which didn't find an application or remained undeveloped for a long time (say at least a couple of decades) but then found its way to success?

There are a lot of strategies that can help to avoid it being total hell indoors in this hot weather. We've had many threads about Air Con and Air Coolers but these things are not widely used in the UK and it's too late to contemplate AC because they've all been sold!! There are other ways, though.

Is it not a huge error in the flight laws and the MCAS software to execute a nose down maneuver at any altitude? Should the system not have a rule to prohibit such a maneuver below a minimum altitude threshold?

At least three items around March 14: new documents from Einstein, a coin commemorating Hawking, Pi-Day, Albert Einstein was born on March 14, 1879. Among various documents of Einstein (acquired by Hebrew University to update their collection of his documents in time to celebrate 140 years since Einstein's birth), there was a page that had been missing from his attempt at a unified field theory...

Let's assume that the technical problems were solved and we had a working design for a fusion reactor with similar economics to existing fission reactors. Then my question is, is there any reason to believe that there would be greater public acceptance of this technology than there is of fission technology?

Phil Plait, creator of Bad Astronomy, has an article on Planet 9. Overall, it's pretty good, but there was one part that got my hackles up: "Mike Brown and Konstantin Batygin (who have been the leading force behind the idea of Planet Nine being out there) have published a paper showing that the alignments are not from any observation bias, and in fact the chance of the alignments..."

1.) Using the notion of double integrals prove that $$B(m,n) = \frac{\Gamma (m) \Gamma (n)}{\Gamma (m + n)}\; \;(m \gt 0\,,\, n\gt 0)$$ where ##B## and ##\Gamma## are the Beta and Gamma functions respectively.

CRISPR gene editing is a newly developed tool that allows researchers to easily make changes to an organism's DNA. There is much interest in using this technology in clinical applications, but there have been major concerns surrounding the safety of the technology, including whether the gene editing approach leads to unintended, off-target mutations elsewhere in the genome...

The Periodic Table is 150 years old sometime this year (I could not find its exact birthday).
Good job Mendeleev! Here is a Science magazine news info graphic on how it has changed over time (before and after Mendeleev). The graphic came out a while ago, but was not working then. Now it does.

I am writing a document for my students about the proper use of ##\LaTeX##. There are some things that always scorch my eyes, like improper italics [##sin(x)##] or incorrect typography of units [##128kg##]. I wonder those of you who are sticklers for typography have other pet peeves of the kind.

Physics, Economists, Biologists, Astronomers and my brother all love the word "Random", as that allows allows them to get out of clockwork processes and allow for variations due to unknowns or whatever else. But, how does a Mathematician reconcile itself with the idea of random? There's no axiom for "choice", no function for "random value", no explanation of what "chance" is...

A researcher from Texas Tech University presented her findings at the recent AAAS Meeting, and found that most people started to believe in the Flat Earth idea after viewing YouTube videos! Interviews with 30 attendees revealed a pattern in the stories people told about how they came to be convinced that the Earth was not a large round rock spinning through space but a large flat disc doing much the same thing...

Published this week in the journal Science, researchers report that they have devised a eight letter alphabet for DNA and RNA: The work builds off of previous work, which had expanded the genetic alphabet to six letters. The researchers call their eight-lettered nucleic acids "hachimoji," Japanese for eight letters. The four new letters seem to function just as well as the original four DNA letters, and the researchers...

Mitochondria are the energy producing organelles in the body which make energy by adding a chemical bond converting a di-phosphate ADP to ATP (tri-phosphate). The problem is the precise machinery about how this works is not entirely known. The oxidative phosphorylation system which is composed of 5 large protein complexes known as complexes I-V are responsible for making ATP which is shown in any high school textbook...

This week I am at "General Relativity as a Challenge for Physics Education". Here are a few slides from Bernard Schutz Monday morning talk "Intuition in physics: What is a physicist anyway?"
Funny... he says that, recently, he has been using Hartle's textbook for his undergraduate class
because he felt his audience needed a "Physics-first" text rather than a "Math-first" text like his own...

Time for our new winter challenge! This time our challenge has also two Computer Science related questions and a separate section with five High School math problems. Enjoy!

I recently learned that Bismuth is actually radioactive with its longest lived isotope having a half-life of about 20 quintillion years. As a very basic question, what determines whether an element/isotope will be radioactive? Is there something special about certain isotopes that makes them stable? Are no elements truly stable, but just have half-lives too long to accurately measure?

While chess hasn't been solved yet, other games have. For example, I know that in in some games, like connect four, if both players play perfectly, the player who goes first will always win. On the other hand, some games, like tic tac toe, a perfect game will result in a draw; in fact, I recently found out that this is true for checkers as well. What I'm wondering though, is if it's possible to predict which scenario a perfect game...

This Science News article reports that researchers using a modified adenovirus (that normally causes mild respiratory infections) that only grows in retinoblastoma tumor cells, researchers were able to improve upon (but apparently not cure) the results of cancer drugs in rabbits and mice. Trials in children (where most cases occur) are beginning...

I created this thread because every online resource I have examined to date has been largely worthless- either totally over-engineered complexity or superficial garbage (can you tell I am irritated?). The problem is simple: optimize DSS image stacking and post processing based on quantitative image data. The essential metrics are 1) signal-to-noise ratio and 2) dynamic range...

Since there seems to be a bit of confusion on this, I thought I'd just post a brief summary. Just some terminology: Superobserver: Somebody who measures another observer, i.e capable of resolving the complete quantum state of another observer and performing measurements on it. Hyperobserver: Like a Superobserver, but also capable of using a unitary evolution to reverse...

We commonly see lists of "best science" both here on PF and elsewhere. I think it is time for a little friendly rivalry from the engineering side. I arbitrarily chose 100 years as the period. The wheel and Roman aqueducts were great engineering but not much fun for us to talk about because we don't know much about the engineers...

Rules: a) In order for a solution to count, a full derivation or proof must be given. Answers with no proof will be ignored. Solutions will be posted around 15th of the following month. b) It is fine to use nontrivial results without proof as long as you cite them and as long as it is "common knowledge to all mathematicians". Whether the latter is satisfied will be decided on a case-by-case basis...

Happy New Year! It's been another incredible 365 days spent on PF! Congrats to all who were nominated as it's a true honor. It should be remembered each voting list could easily have been ten times as long. We have an amazing core of members here at PF. A member may have won more than one category, but can be awarded for just one...

PF owes much of it's success because of our tireless volunteer Mentor crew. In 2018 they dealt with well over 3000 reports! Some take 5 minutes and some take days to handle. But community policing is just one of dozens of hats they wear. I am always proud to learn about a Mentor taking extra patient time to explain a science concept, forum issue or question in private that literally takes days. These situations are not rare...

I've moved to a "new" house - built about 350-400 years ago. Firewood in a stove kind of works for heating a few rooms, but not the full house. So far it seems like the grid power tends to die about twice a month. Temperatures is expected to reach -25C (-13F) for the coldest couple of weeks every winter. Hence I need some kind of backup power and heat source...

CLIC is a proposed accelerator, potentially at CERN, that would collide electrons and positrons at energies far above what previous colliders achieved. Its overall energy would still be below the LHC but (unlike at the LHC) all the collision energy is available for the creation of new particles - it would combine the approximate energy reach of the LHC with the cleanliness of elementary particle collisions...

Rest in Peace, Dr. Gregory Greenman, aka @Morbius. Underneath the occasional curmudgeon-like exterior, Morbius was a gentleman and a scholar and a PF friend. I was wondering why we had not heard from him for a few years so I began looking and, alas, sadly, I came across a January 2015 obituary for him.

Another year has passed and another year I am so thankful to our community. It's an example for the rest of the world how an open community full of members with different backgrounds, genders, language, age, educational background, jobs etc etc can come together in peace, fun and production to learn and explore quality math and science topics...

Ok math and science brains, it's time to get creative and festive! Using LaTeX or on a graph can you build an amazing christmas tree or holiday/winter scene using math equations? DESMOS is a great tool to use. Post your equation set and photo and maybe you'll get gold membership!

Science Magazine is holding its annual vote for the people's choice for Breakthrough of the Year, which will accompany the editors' own choice. Voting is open until Dec 5, after which they will narrow the field to the top for choices for a second round of voting.

Over the last 2 weeks I have noted the first sunspots of the new solar cycle 25. How do I know they are spots of the new cycle ? Because they are higher latitude and opposite magnetic polarity. Before I show an image, a little history and science. Over the many observed solar cycles, a feature of the sunspots and the 11 year cycle...

Rules: In order for a solution to count, a full derivation or proof must be given. Answers with no proof will be ignored. Solutions will be posted around 15th of the following month. It is fine to use nontrivial results without proof as long as you cite them and as long as it is "common knowledge to all mathematicians". Whether the latter is satisfied will be decided on a case-by-case basis...

Is it possible to introduce the concept of a gradient vector on a manifold without a metric?

In traditional logic, a system is inconsistent if it can lead to a contradiction. Furthermore, if the inconsistency is non-explosive (not all consequences follow from the contradiction), then the system is para-consistent.
Both definitions fail to distinguish between the following two real-world scenarios...

At very high energies Earth absorbs a relevant fraction of neutrinos passing through it. Experiments receive more of these neutrinos from above than from below and the difference depends on the mass of Earth. So why not measure it?

Neutrino tomography of Earth

The uncertainty is very large, of course. While the result is very close to the number from gravitational measurements they have a 25% measurement uncertainty. Larger datasets and KM3NeT will help reducing the uncertainty. While unlikely, Earth might have accumulated something dark matter like - it would appear in gravitational measurements but not necessarily in neutrino absorption data.

Apart from the overall mass they also measure the density in different regions of the interior of Earth and confirm that the core has a higher density than the surrounding material. Again no surprise (seismic measurements have measured this long ago) but a nice confirmation, and with a lot of potential for future improvements.

Today I came home to find very discrete lines of colored light on my living room floor. Can anyone help me to explain this phenomena? I am familiar with dispersion but am wondering how the combination of glass and blinds is creating this effect. When I rotate the shutters as you can see from the pictures, the colors changed...

If you've seen breaking bad you probably already know what I'm asking. In this episode I'm watching, they are hand cranking the generator to recharge the battery. They are moving nowhere near as fast as the motor would have spun it. My dad had a hand crank device that was, more or less, a toy. So I'm sure they were producing some electricity...

According to nonperturbative QCD, quarks and gluons don't exist and in nonperturbative QED with two spinors (e.g. proton and electron) hydrogen isn't composed of a proton and an electron.

Every so often we get requests for engineering projects to work on. One common theme that I've seen is Kickstarter / Indiegogo campaigns for novelty bicycles to solve that last mile problem in urban transportation...

In the last years a discrepancy between two methods to measure the Hubble constant appeared. Measurements based on redshift and the cosmic distance ladder produced results of about 73 km/(s*Mpc) while measurements based on the cosmic microwave background lead to results of about 68 km/(s*Mpc). While not completely outside the uncertainties the difference was still curious...