Featured Science Threads - Page 9

Below is a curated list of some of the most interesting and highest quality science news and discussions on Physics Forums. News and discussions are added weekly. Also check the Hot Threads page for discussions choosen algorithmically.
Featured Thread: How close is Earth to the closest black hole?
Is it astronomically known what the closest distance is between Earth and a black hole? The article... says
The Milky Way teems with black holes — about 100 million of them.Based on this estimate, and taking into account the relative density of matter based the distance from the center of the Milky Way, what would be a reasonably accurate estimate of the distance between Earth and the closest black hole?
Featured Thread: Science and math books with nice covers
Serious books on math, physics and related sciences usually have covers which are quite boring and visually not very attractive. (Books that have something to do with Universe are a common exception, but when you see a few of them you have seen them all.) But sometimes, covers are really interesting and/or beautiful. Here you are encouraged to present examples...
Featured Thread: B Level Explanation of Conduction and Resistance
Students seeking “deeper” understanding of basic electricity, frequently come with one of the following misconceptions. 1.Electrons are like balls, they start with potential energy and gain kinetic energy. They deliver their energy to the far end of the wire by filling a bucket. 2. Electrons are like pods filled with energy. The pods burst as they go through a resistor, and they are all used up by the time the wire reaches ground.
I am seeking a B level explanation of conduction and resistance that is not based on analogies...
Featured Thread: Psychology: How will we react to discovery of alien life
The pilot study analyzed news scientific reports (with software), and gave questionnaires to study subjects after reading some specially chosen reports as well. You are best advised to read the phys.org link first before generating conclusions. Limited study.
Featured Thread: The Forgotten Anniversary: 100 Years since Emmy Noether's Theorems
We shouldn't have forgotten this: On January, 25th it has been 100 years, a complete century, since Emmy Noether published her paper "Invarianten bestimmter Differentialausdrücke" (Invariants of Certain Differential Expressions, Göttingen 1918). It is still the basic concept of so many physical models, from classical mechanics to the standard model of particle physics...
Featured Thread: Can indistinguishable particles obey Boltzmann statistics
Many text books claim that particles that obey Boltzmann statistics have to be indistinguishable in order to ensure an extensive expression for entropy. However, a first principle derivation using combinatorics gives the Boltzmann only for distinguishable and the Bose Einstein distribution for indistinguishable particles (see Beiser, Atkins or my own text on Research Gate). Is there any direct evidence...
Featured Thread: Warm air goes up... reason on a microscopic scale?
I was wondering about the microscopic reason warm air rises up, while cold air comes down. I am aware of the macroscopic reason - density changes. But what happens microscopically? Decrease in density means that the gas molecules are widely spaced out, but their mass remains the same. Then why does warm air go up?
Featured Thread: Why did you start learning physics?
Why did you decided to learn physics? What was your motivation? What is your personal physics story?
Featured Thread: Success! SpaceX Falcon Heavy Launch
"Years in the making, the commercial spaceflight company is preparing to launch its first Falcon Heavy rocket, which as its name implies, is a heavy-lift booster built from a core stage and two of SpaceX's Falcon 9 recoverable rockets. According to SpaceX, when the Falcon Heavy lifts off, it will be "the most powerful operational rocket in the world by a factor of two."
Featured Thread: Possible explanation for muon g-2 anomaly: Gravity?
For many years, the measurements of the Landé g-factor of the muon have been puzzling, as the experimental value and the theoretical predictions showed some disagreement - 3.6 standard deviations for the last years. Experimental and theoretical uncertainties have a similar size, so work on both sides helps.
Muon g-2 at Fermilab is currently taking more data to improve the experimental result...
Featured Thread: Super Blue Blood Moon
I just wanted to see anybody's opinion on the super blue blood moon yesterday night (at least for me). I couldn't catch a glimpse of it in Sydney since it had been very hot for a few days and clouds had taken over the sky. Did anybody see it? Anywhere in the world besides Oceania?
Featured Thread: What are you reading now? (STEM only)
What book are you reading now, or have been reading recently? Only STEM (science, technology, engineering and mathematics) books are counted.
Featured Thread: Is Gravity a Gauge Theory
I have been reviewing GR lately because as a mentor I find myself now answering more of those questions. I learnt GR years ago from Wald and other sources, but since then have been exposed to the symmetries of the Standard Model. What struck me during this review is I now have a different perspective...
Featured Thread: Contest: Educational experience account (win a book!) 1/24-2/7
The contest task is to share an account of your best educational experience. It may be something you experienced as a student or as a teacher, but should be a good example of how your education or that someone you were teaching benefited from the actions described in the account. Your account may be as long or short as necessary, but make sure to include as much information as is needed to properly appreciate it...
Featured Thread: What Should I Do If My Professors Don’t Teach?
I’m taking physics II and discrete math this semester. Long story short: I’m probably not going to be able to rely on the professors to teach me this semester. I’m really, really hoping that I can get all A’s this year. What do you guys recommend I do? I should note that I’m also working this semester (15-20 hours/week).
Featured Thread: What makes the Navier Stokes equation so difficult?
An article in Quanta Magazine discusses the math behind the Navier Stokes equations, why they are so difficult to solve and whether they truly represent fluid flow...
Featured Thread: Decarbonizing an Engine with Water: Myth or Fact?
I ran across several YouTubes that claim, and apparently demonstrate, that you can clean carbon deposits from a car engine by simply spraying or pouring (very slowly) water into the intake when the engine is fully warmed and running. I've never heard this from a reliable source and my reaction is... What is the real story on this?
Featured Thread: Meteorite older than Earth
The Hypatia Stone is a small meteorite from SW Egypt. Petrographic and chemical analysis by a group of researchers mostly from University of Johannesburg found element abundances and other unique chemical anomalies in the meteorite. They suggest that the object originated in the interstellar dust cloud, likely before the formation of Earth.
Featured Thread: Why were Newton's laws of motion discovered so late?
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'...
Featured Thread: Were all these exoplanets a surprise?
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...
Featured Thread: The Fundamental Difference in Interpretations of Quantum Mechanics - Comments
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...
Featured Thread: Meltdown and Spectre - Every computer/phone at risk
"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."
Featured Thread: STEM jobs for high schoolers?
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...
Featured Thread: Brave New World of Protein Design
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....
Featured Thread: Science Facts Discovered in 2017
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?
Featured Thread: PF Photo Contest - Physics+Maths (12/23-1/5, win a book!)
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!
Featured Thread: Books by Physics Forums Members
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?
Featured Thread: The Birth of a Textbook
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...
Featured Thread: How can we melt ice in a microwave efficiently?
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?
Featured Thread: What should the Mathematics requirements be for a Physics degree
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...
Featured Thread: Drop the Physics Requirement to Encourage More Women Engineers?
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...
Featured Thread: New Kepler results on Thursday (Dec 14)
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...
Featured Thread: How to train myself to be more careful?
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?
Featured Thread: Mind boggling machine learning results from AlphaZero
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!
Featured Thread: GW170608 - Another Binary Black Hole Merger Observed
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...
Featured Thread: Semi-synthetic organism with an expanded genetic code
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...
Featured Thread: Vote for the Breakthrough of the Year
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?
Featured Thread: First Stable Plasma Ring
"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..."
Featured Thread: Update on liquid water on Mars - maybe it is sand?
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...
Featured Thread: What Do Smart Phones (Partially) Replace?
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.
Featured Thread: A perfectly stiff wheel cannot roll on a stiff floor?
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...
Featured Thread: Do you feel safer with self-driving cars on the road?
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.
Featured Thread: Multiple supernovae from a star
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
Featured Thread: CRISPR Based Base Changes
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)...
Featured Thread: Limits of Machine Learning?
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?
Featured Thread: Ed Witten on Symmetry and Emergence
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...
Featured Thread: First Interstellar Asteroid Found
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.
Featured Thread: For those who do their own automotive work
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...
Featured Thread: What are great places in US or UK for a physicist to visit?
As the title says, any ideas of great places that a physicist tourist could visit in US or UK?
Featured Thread: Radial movement in a gravitational field
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...

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