Featured Science Threads - Page 7

This is a topic I've mentioned a few times before. Essentially the structure of matter in quantum gauge field theories is unclear to me. I have no clear question here, just some initial discussion points. So at the first level, it seems a particle based view of quantum field theory is difficult to maintain. In brief on the Hilbert Spaces of interacting field theories there is no well-defined number operator ##N##...

A Soyuz flight that was supposed to launch two astronauts to the ISS had a booster failure (half an hour before this post). The Soyuz capsule separated from the rocket and landed, the crew is fine. Rescue teams got to them quickly. While they had to endure higher g-forces than usual they seem to be in a good condition.

I often ask myself if anyone can learn math to an advanced level? I think that every healthy person can get very good at math. The only condition is that the person is interested in math. Of course, to get on the level of a Field-Medal winner you have to be blessed a little bit. But I think you can reach and understand a lot just by working out hard. What do you guys think? Can anyone learn math to a high level?

Scares of the CERN accelerator creating a black hole that swallows Earth are in the news once again. I know it is not possible for an accelerator to produce such a black hole in practice. But surely it's impossible even in principle. Surely, a particle accelerator creating a tiny black hole that could grow to swallow the Earth would violate the law of conservation of energy...

Summer is coming and brings .... Oops, time for a change! Fall (Spring) is here and what's better than to solve some tricky problems on a long dark evening (with the power of returning vitality all around).

"The LHCb collaboration has found two never-before-seen particles, as well as hints of another new particle, in high-energy proton collisions at the Large Hadron Collider (LHC). Future studies of the properties of these new particles will shed light on the strong force that binds subatomic particles called quarks together." - LHC

I have heard through the grapevine that the Riemann hypothesis has been proven. What I read was this is a claim made by none other than Sir Atiyah himself and that he is planning to give a talk next week. So *if* the statement is true that it is a claim made by Atiyah, then it is of course an extremely serious and probably correct solution...

The Nobel Prize winners of 2018 will be announced during the first week of October, starting with the Nobel Prize in Physiology or Medicine on Monday October 1. As most of us are biased towards physics: The physics prize will be announced Tuesday October 2 @ 11.45 (Stockholm time - CEST) at the earliest.

Work in quantum foundations is partly considered important because of the hope that the way we think about QM may point to a road to quantum gravity. Lucien Hardy, who is well-known in quantum foundations for his reformulation of QM in terms of five "reasonable" axioms, is one of the people who try to make this really tangible...

The recent rise of incentivized competitions for humanity has prompted me to create this thread, to tell PFers what's out there and to share my meager experienced in "almost" entering one. The largest and arguably most influential one has been the XPRIZE organization which finds sponsors and puts out many competitions to solve some of our worst problems. Its a competitive game with many teams worldwide...

Can the journey be completed within the lifetime of a human adult? Assuming we have got around little problems like having an adequate form of propulsion, shielding from radiation, and avoiding deadly collisions with milligram sized dust particles. Let's say our engines can provide constant acceleration then deceleration at 1g.

I have found that some people say “yes, definitely”, and other days “no, definitely not”. Those who say “no” seem to regard PLA as merely a neat way of packaging the equations. Those who say “yes” seem to regard PLA as somehow fundamental. Is there a consensus among physicists that I am unaware of? If not, why not? What could the physical meaning of PLA even be?

The swampland conjecture is currently a very hot topic. Can someone explain, in simple terms, what exactly the swampland idea is? In particular, the conjecture states that the string landscape is surrounded by an even larger swampland of consistent-looking semiclassical effective field theories, which are actually inconsistent. What exactly does it mean that an effective theory is inconsistent?

Summer is coming and brings a new basic math challenge! Enjoy! For more advanced problems you can check our other basic level math challenge thread!

Summer is coming and brings a new basic math challenge! Enjoy! For more advanced problems you can check our other intermediate level math challenge thread!

Double blind peer review is a process in which not only the author does not know the name of the reviewer (which is the standard practice), but also the reviewer does not know the name of the author (which is not a standard practice). What would happen if the scientific community suddenly decided to shift to the double blind review process? Who would be the winners? Who would be the losers?

I am trying to analyze the game of tennis. I started very simply by analyzing just the ground strokes, ignoring the serve, and calculating the odds of winning a single point given the odds of returning each ground stroke. I got a surprising (to me) result showing that the player to goes first always has a lower probability of winning the point than the opponent...

This is something many of us instructors have to deal with, something that was never an issue when I was still in college. Students now come to class equipped with notebook laptop, tablets, and of course, the ubiquitous cellphones. Different instructors have different policy on the use of the electronics, ranging from an outright ban, to "I don't care if you use these during class session as long as you don't distract...

The 2018 Fields Medal has been awarded to: Caucher Birkar, Alessio Figalli, Peter Scholze, Akshay Venkatesh. More inside...

I'm having trouble in studying. I am studying full time from Monday to Monday but I just cannot get focused all the time, I realized that more than half of the time I'm sleepy or struggling to maintain my focus. I'm doing my degree in physics and I feel like I need to study full time, but I just can't do it, what should I do?

The dramatic collapse of a bridge in Italy with many fatalities has been the big item of news all over Europe. I just wonder if the qualified people here can throw any light not on the specifics which would be hard for them to know, but in general...

Summer is coming and brings a new basic math challenge! Enjoy! For more advanced problems you can check our other intermediate level math challenge thread!

Summer is coming and brings a new intermediate math challenge! Enjoy! If you find the problems difficult to solve don't be disappointed! Just check our other basic level math challenge thread!

From the Vice article: "Who doesn’t like a pretty idea? Physicists certainly do. In the foundations of physics, it has become accepted practice to prefer hypotheses that are aesthetically pleasing. Physicists believe that their motivations don’t matter because hypotheses, after all, must be tested. But most of their beautiful ideas are hard or impossible to test. And whenever an experiment comes back empty-handed..."

Today (AUG 1) is RNA Day, an international celebration of one of the most versatile biomolecules in existence. What are some areas of RNA research that excite you most? Some of the most intriguing areas of current research to me (with example links for further reading)...

What I am struggling to come to grips with is how knowing physics, the topics typically taught in a high school intro course, can be useful in everyday life. I am not looking for everyday examples of physics concepts. I mean real actual examples of using Newton’s laws or momentum in real life purposefully. Can you think of a time when you actually used your physics knowledge in everyday life?

As the title says, what makes a decision problem NP complex? Is it application of the definition (as in: solvable in polynomial time by a non-deterministic Turing machine)? Also, if P does not equal NP, does it mean that NP problems can only be solved in O(exp(n)) time/steps?

We are all members of an amazing community of science and math passionate people from all over the globe. However, "amazing" doesn't just happen over night or by itself. "Amazing" happens when members take pride and responsibility for the health of the community...

Summer is coming and brings a new basic math challenge! Enjoy! For more advanced problems you can check our other intermediate level math challenge thread!

Summer is coming and brings a new intermediate math challenge! Enjoy! If you find the problems difficult to solve don't be disappointed! Just check our other basic level math challenge thread!

I have completed post grad in Physics and in the transition phase between post grad and Ph.D. I am interested in cosmology and also completed a post grad course on Astrophysics and Cosmology. Can anyone enlighten me about what are the current debates and active topics of research going on in Cosmology?

Take note of today's Obied-Ooguri-Spodyneiko-Vafa 18. Curious situation: After it had influenced much the development of the string theory community’s attention and almost all of its public media perception since 2003, after what must be thousands of followup publications, the argument of KKLT 03 for a large finite number of metastable de Sitter spacetime vacua of type IIB string theory...

Nathan Myhrvold has raised questions about the accuracy of data NASA uses to track asteroids that may impact the earth. Myhrvold is a former Microsoft chief technologist and a guy with many diverse interests.
Specifically he has questioned the size information and how it was derived. This concerns the Neowise project which was derived from the Wide-field Infrared Survey Explorer (WISE) project...

"By analyzing super-torsion and brane super-cocycles, we derive a new duality in M-theory, which takes the form of a higher version of T-duality in string theory. This involves a new topology change mechanism abelianizing the 3-sphere associated with the C-field topology to the 517-torus associated with exceptional-generalized super-geometry. Finally we explain parity symmetry in M-theory"...

In discussing stuff in another thread I used the standard Dirac notion expanding a state in position eigenvectors namely |u> = ∫f(x) |x>. By definition f(x) is the wave-function. I omitted the dx which is my bad but the following question was posed which I think deserved a complete answer. It was also off at a tangent to the main threads topic so really required a separate thread...

Earth physics in action! Volcano erupts near homes in Hawaii causing evacuation of residents Fri 4 May 2018. Check this thread for the latest news, analysis, photos and video!

The Northern Quoll is endangered marsupial in Northern Australian. Its main problem, leading to its population decline, was eating the invasive and toxic cane toad. A population of them was introduced to a couple of islands (free of both cane toads and predators), where in 13 generations a large population was built up from which animals were reintroduced to the mainland. Problem is that the quolls lost their fear of predator scent...

CRISPR-Cas9 technology provides scientists with an easy way to introduce targeted genetic changes to DNA and a number of different companies are looking at ways to use CRISPR to fix genetic diseases in humans. Two groups of researchers, however, have identified a major issue with CRISPR gene editing that has important implications for the safety of the technique...

Summer is coming and brings a new intermediate math challenge! Enjoy! If you find the problems difficult to solve don't be disappointed! Just check our other basic level math challenge thread!

Curiosity has found seasonal occurrences of methane and some organic molecules on Mars. Both or possible indicators of carbon based life processes, but can have other non-biological explanations. Methane has been intermittently found previously on Mars. However, lacking a continuous long term record the seasonal variations were not obvious. The seasonal variation could be explained by either biological...

Summer is coming and brings a new basic math challenge! Enjoy! For more advanced problems you can check our other intermediate level math challenge thread!

I have been wondering about the validity of Maxwell's equations in quantum physics. I looked in the internet and it seems from what I understood that: Maxwell's equations are valid for any situation, classical or quantum. In fact, maybe it holds more legitimacy than Schrodinger equation since it is a relativistic (invariant) set of equations...

New evidence in the search for the 'sterile' neutrino. Can someone comment on this please.

Here I would like to see interesting challenges for artificial intelligence, which seem very hard for AI and yet in the spirit of what AI usually does. Here is my proposal: Let us feed the machine with a big sample (containing, say, a million numbers) of prime numbers and a big sample of non-prime numbers, without feeding it with a general definition of the prime number...

The energy of electron-positron colliders is limited by the acceleration gradient (energy per distance) and the length of the accelerator (=the cost). In the past the energy mainly increased from making accelerators larger. Much larger accelerators than today get prohibitively expensive, however. More compact designs could keep them affordable. While conventional cavities still make some progress...

π is defined by the ratio of the circumference (R) of a circle to its diameter. The area of the circle is πR². Can this be derived without calculus (or Archimedes method)?

The CMF armor on collision literally converts the projectile into small particles, spraying out. This is interesting and definitely not my area. Questions: the particles resulting from the hit have to have kinetic energy, if some particles are redirected to unprotected area (example: projectile hits high, just above the top of the sternum, redirect up into the lower jaw), are they a problem?

What is the best temperature water for rinsing dishes? I've googled this question, and gotten many answers, very few of which have any rational basis for them whatsoever. For example, some people say that it's better to use hot water, because the soap dissolves better in hot water. However, it's not at all clear to me that dissolving is the underlying mechanism for getting rid of the soap...

Extrapolating to a sphere centered on Earth with a 100 ly radius, this sphere should contain about 625 stars bigger than red dwarfs and 8 black holes, of which about 4 would be in binary systems. Systematically observing the Doppler shifts for these 625 stars over a period of time should detect any invisible massive companions. Is such a search currently happening or planned?

Sabine Hossenfelder recently wrote about an old theory of quantum gravity due to Weinberg: asymptotically safe quantum gravity. Is anyone familiar with this idea? What I couldn't figure out from the article is whether asymptotic safety is an approach to making consistent quantum field theories, or whether some quantum field theories just happen to be asymptotically safe...