Featured Science Threads - Page 11

CHALLENGE:
Prove that if ##P(x), Q(x), R(x)## and ##S(x)## are all polynomials such that ##P(x^{5}) + xQ(x^{5}) + x^{2}R(x^{5}) = (x^{4} + x^{3} + x^{2} + x + 1)S(x)##, ##x - 1## is factor of ##P(x)##.

It is usually referred to as Phonons for sound waves in solid. But, where it gets confusing, is in gases and air. Some still call it Phonons, others say, Phonons can only be used in solid states. So what is the Quantum of Sound in Gases/Air?

Beginning with a cube with each side of length 1", drill a 1" diameter hole all the way through in each of the 3 perpendicular directions. Find the remaining volume.

It is often said that Poincare was the last universalist, i.e. the last mathematician who understood more-or-less all mathematics of his time. But Hilbert's knowledge of math was also quite universal, and he came slightly after Poincare. So why was Hilbert not the last universalist? What branch of math he didn't understood sufficiently well to deserve this title?

"China is aggressively attempting to displace the US as the world's scientific superpower, and the US is aggressively attempting to abandon it's scientific superpower status, while Europe seems all but recovered from WWII. ....". I was wondering how the rest of you on PF feels on this regard.

I'm curious on just how much modern physics can be understood qualitatively, without equations. I know that people can understand F=ma with just words. For example, the acceleration an object experiences is directly proportional to overall force pushing or pulling on the object. The more force the more acceleration and vice versa. Of course, this ignores the fact that its a differential equation...

It's strange to me that multiplication and division are considered fundamental operations.
It makes sense for me that addition is a fundamental operation but multiplication is just like a function or algorithm that takes several numbers and apply additions. This is true even for multiplication with real number.

What do I mean by inhibit, you know taking patent or taking permission to use its license takes some time and money and if we think in large scale, today, almost every company spends lots of time to protect their tech. My point is maybe all these things slows the improvement in technology. I think if everything were free to use things would get faster in terms of tech...

Suppose that there are 2 companies. One of them is yours and other company publishes a product which can affect your situation in marketplace.Is it ethical to buy the product and resolve it by reverse engineering to get an idea to counterattack? It's not about producing similar technology but getting an idea to help you to think differently.

In a nutshell, does Newton's "action = -reaction" law apply to massless particles? If a spaceship directs a condensed light beam on its own heat-resistant photon sail, what would happen?

"The "scicomm" effect may be a contributing factor to people being less willing to accept science, but I don't think it's completely at fault. I think you have to go deeper and look at phenomena like confirmation bias. A reasonable person who is willing to be swayed by the balance of evidence will consider details behind scicomm statements." - Choppy

Yes, 7 planets around TRAPPIST-1, all about Earth-sized with quite precise radius estimates from transits, and approximate mass measurements from transit timing variation. 3 are too hot for liquid water (b,c,d), 3 of them in the habitable zone (e,f,g), 1 (h) is too cold. The three planets seen before were the innermost two and the outermost one, so all potentially habitable planets are new. Probably tidally locked (all?).

This paper; Non-extensive Statistics Solution to the Cosmological Lithium Problem, offers a plausible solution to the cosmic lithium problem that has baffled astrophysics, and BBN aficionados, for decades. Unlike prior efforts, it does not invoke any BTSM particles or new physics, just a twist on statistical modeling which looks entirely reasonable...

I'd have to think Jupiter from Mars would be the brightest but after that it's hard to say. Any guesses?

Woit over at his blog "not even wrong" considers string theory based multiverse to be fake physics. Is string theory based multiverse fake physics?

Say you've got four 4s -- 4, 4, 4, 4 -- and you're allowed to place any normal math symbols around them. How many different numbers can you make? It's best to think of a number and then try to make it.

Supposing immigration is heavily restricted in the future will there be an increased demand for home-grown US STEM in the next 4-8 years? How will these new rules impact the job market for US citizens? What sectors do you think will experience the biggest surge in demand?

"Producing metallic hydrogen has been a great challenge to condensed matter physics. Metallic hydrogen may be a room temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures..."

All natural life uses the same four bases in its DNA: A paired with T and C paired with G. Scientists worked on adding more bases. Just putting them into DNA is not hard, the challenging part is to keep them there: They should not get removed/replaced during reproduction. This has now been achieved...

Are there fundamental limits on the accuracy for measuring both position ##q## at time ##t## and momentum ##p## at time ##t+\Delta t##, with tiny ##\Delta t##? If yes, why? If no, why can't one then measure (in principle) both ##q## and ##p## arbitrarily well at the same time ##p## (which is not allowed by Heisenberg's uncertainty relation), by taking ##\Delta t## sufficiently small and noting that any measurement takes time?

We're all pretty smart people on this forum, but what little things does your mind, for whatever reason, just never want to learn? For me, it's the stupid trig functions. I can't just put angles and numbers on a triangle and solve anything. I have to tell myself "SOH CAH TOA." Every time...

One of the things I read and hear about is how poorly the American educational system teach math or science. I would like to pose the opposite question: what does the American educational system (K-12) teach well? What, to your knowledge or experience, do students graduating from the American educational system in general come away knowing best?

Humans, other animals, plants, fungi and almost all other forms of complex, multi-cellular life are known as eukaryotes. How eukaryotes evolved from simpler prokaryotic organisms is a major question in evolutionary biology. The current view is that eukaryotes evolved from the fusion between a bacterium (which would eventually become the mitochondrion) and an archaeal host through a process called endosymbiosis.

I watched the 6-episode series called Mars this week. Elon Musk kept emphasizing that humans must spread out to at least one other planet to ensure human survival in the event of some extinction event on Earth. Wouldn't colonization of the Moon achieve the same purpose? Seems like that would be a more viable option.

The missing element mystery in the earths core may have been solved. Lead researcher Eiji Ohtani from the University of Tokyo told BBC News: "We believe that silicon is a major element - about 5% [of the Earth's inner core] by weight could be silicon dissolved into the iron-nickel alloys."

I was zooming around the NE region of the South Island of New Zealand in Google Earth today and discovered a classic example of offset stream channels across a major fault, the Awatere Fault. The Awatere Fault which is one of the major faults that the Alpine fault splinters into in the upper South Island. It's companions are the Wairau Fault...

"The development of quantum mechanics in the first decades of the twentieth century came as a shock to many physicists. Today, despite the great successes of quantum mechanics, arguments continue about its meaning, and its future."

"Researchers have classified a brand-new organ inside our bodies, one that's been hiding in plain sight in our digestive system this whole time. Although we now know about the structure of this new organ, its function is still poorly understood, and studying it could be the key to better understanding and treatment of abdominal and digestive disease."

I can create a small vacuum in my mouth to move that "string" of spagetti into my mouth. I know it is possible, but I do not understand how spaghetti is possible to suck in if the shape is even and round like a "piston". I have learned that pressure is acting angular to any surface. With the spaghetti, that surface will cause the pressure to act 90° to it, and (in my thoughts) not be able to create a force...

The Nobel prize in chemistry for 2016 has been awarded "for the design and synthesis of molecular machines." These are fascinating constructions made up of just a few molecules, so they are the smallest machines possible. It is far from trivial to get these things working, especially since thermal noise is important at that scale (although in some cases, thermal noise can be rectified and serve as a source of energy)...

The situation of course is that I tell somebody that I am studying math, and if I mention some specifics, like mention Topology or Algebra, (which I have to sort of explain is not "college algebra"), or whatever. Then comes the question "So what's this used for in..you know, real life?" As I see it there are two extremes to answer this question...

You know a book which is rarely cited, mentioned or recommended, quite unknown even to the experts, and yet you have discovered that this book is really great? Please share it with us!

The problem I have is if the human body was able to mutate, without any design at all, completely mindless mutations, why is it that our arms don't have big lumps all over them or, our rib cage have random points sticking out of each one, or an extra toe poking out the side of our foot. What I cant understand is why did only the useful organised mutations...

Any pointers about where to get information and perhaps pictured of the different whiteboards shown in Big Bang Theory? I am particularly interested on the season where Sheldon abandons string theory; the boards for this chapter (155, season 7 ep 20, aired 10th April 2014) seem to show some M-theory + D-branes generic content, and the next day seem to be some model building with GUT groups but not the common presentation....

I've often read that beam-powered propulsion is the only basic interstellar propulsion concept without physics problems. To me, that doesn't seem far from the truth. However, for a long time I've felt that the biggest obstacle to overcome is the beam divergence problem. Most of the concepts I've read about use a single laser...

I know that rain is charged and the lightening is a discharge, and both are relative to the ground, I think, but I don't know the relative polarities... is there some way that the charged rain drops are being momentarily attracted upwards by the lightening or its regional effects? Could it be that the metal car itself is altering its charge and somehow repelling the rain charges for a moment?

We hear so often of the great advances of medicine. Every day one reads of breakthroughs in research in the news. But then I never hear of it again. I'm not a doctor or biologist, but am wondering what are the important discoveries ***and which had practical applications*** of the last 20 years?

A popular video I just watched described Fred Hoyle's discovery that the elements of the universe are created in stars. Key to his theorizing was the prediction that fusion would produce of a new state of carbon that had never been observed and which theory predicted would be unstable. Hoyle believed that under the physical conditions present in stars this form of carbon could exist. What was this new type of carbon?

This is the problem: A person blows through a straw between two empty soda cans. Do the cans move closer together or away from each other? Explain why they move the way they do. Partial answer: The cans will move closer together. Given that information, we can conclude that the air pressure in the region between the soda cans must be lower than normal...

Here is an interesting item I would like to share. It seems that China has drastically pushed the boundaries of power transmission grid operations. They boldly go where no man has gone before...

So I'm about to be done with my first class in programming where we learned C programming. Unfortunately, I don't actually know what you can do with it. All of our programs in my class have involved us programming and running everything using Visual Studios, not developing standalone executables or something...

For whatever reason, pilot waves have been mentioned quite a lot recently, and so I decided to take a closer look at it. I've seen many people claim that it makes the same predictions as standard quantum mechanics (Schrodinger equation, etc.), but I was pointed to this paper which seems to show that there is actually an issue with the predictions of the pilot wave theory...

When I look at a scene and then later recall that scene, I am accessing a memory of that scene. But what is it that is stored in memory for me to access? Is it the sensory input or is it the constructed visual experience?That is, do we construct the recalled visual scene in the same way that we construct the original experience (from neural representations of the raw sensory input), or do we recall the constructed scene?

"Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon..."

For centuries, scientists argued whether light was waves or particles. Light scattering with other light would favor the particle concept. Today we know both models are wrong, but quantum electrodynamics also predicts this scattering - just with an incredibly tiny rate, so it has never been observed before. Lead-lead collisions at the LHC allow a search for it...

This article from 1820 covers many advances in technology; Slavery; Prosthetic limbs; Voyage to the Moon denial; Mammoth power; Newton's Principia; Airconditioning; Recorded voice; Whale power, and Energy from underground...

"Remarkable progress of quantum information theory (QIT) allowed to formulate mathematical theorems for conditions that data-transmitting or data-processing occurs with a non-negative entropy gain. However, relation of these results formulated in terms of entropy gain in quantum channels to temporal evolution of real physical systems is not thoroughly understood..."

I was in a primary school class room the other day and the teacher asked me for help with this geometry problem, that he had set for his class as an extension challenge, but then realised he couldn't do.
The known angles are marked in degrees. We have to find the angle x. I spent five minutes trying to do it on the board...

Superb, utterly superb. Got my copy this morning. QM is developed from symmetry, the only thing not derived is the Born Rule. QM is simply group theory applied to a complex field just as mechanics is group theory applied to particles. Very very highly recommended.

Met theoretical physicist James Gates at the WAPT meeting tonight. He said he'd be interested in doing an Insight Interview. Let's get some good questions rolling! Here are some links if you are not familiar with his history and work...