Featured Science Threads - Page 10

I thought I would post my thoughts/progress on designing and building an automatic tennis ball launcher for my dog. The little fella gets a bit bored during the day when we are at work, so I want to build him this so he has something to do other than push a basketball around the backyard. Any and all advice/criticism is appreciated.

I've been waiting for this for a long time and it's just a little more than a year away now. This will be the opportunity of a lifetime for people in the U.S. The 2017 solar eclipse will be visible across the width of the entire U.S! The points of Greatest Eclipse and Greatest Duration are going to occur on opposite sides of the Kentucky - Illinois border.

I was trying to help (elsewhere) a student with some QM related problem and I realized something. When discussing QM we underline the fact that electron doesn't behave as a particle, it behaves as a wave. Yet when we explain wave function we say something like "square of the wave function is a density probability of finding the electron" - which seems to suggests to students the electron is a particle that can be found...

The authors looked for signals of potential moons in the Kepler transit data. There is some weak evidence that a group of smaller moons exists, but the measurements are not accurate enough to pin that down on a star-by-star level. One particular planet, however, Kepler-1625b, has very curious features in all three observed transits. The Hubble telescope will observe the next transit in October this year.

"Researchers have demonstrated they can efficiently improve the DNA of human embryos. The first known attempt at creating genetically modified human embryos in the United States has been carried out by a team of researchers in Portland, Oregon, MIT Technology Review has learned. The effort, led by Shoukhrat Mitalipov of Oregon Health and Science University, involved changing the DNA..."

The chancellor of the California Community Colleges system believes that students who are not majoring in math or science should not have to take intermediate algebra to earn an associate degree. California has the largest community college system in the US, and what goes in California sometimes spreads across the country. What do you think?

Is it possible to detect a single phonon? If yes, can it be detected at a well-defined position?

The CMB establishes a record of ancient acoustic oscillations in the baryon-photon plasma. We’ve been studying how these primordial sound waves evolve, and how to analyze the last scattering surface to learn about them. Now it’s time to confront their origin: what process composed the cosmic symphony? A few different proposals have been advanced over the years to explain the origin of the primordial perturbations.

"The missing square puzzle is an optical illusion used in mathematics classes to help students reason about geometrical figures; or rather to teach them not to reason using figures, but to use only textual descriptions and the axioms of geometry. It depicts two arrangements made of similar shapes in slightly different configurations. Each apparently forms a 13×5 right-angled triangle, but one has a 1×1 hole in it." Can you figure out an easy way to inspect it?

"In a discovery that concludes an 80-year quest, Stanford and University of California researchers found evidence of particles that are their own antiparticles. These 'Majorana fermions’ could one day help make quantum computers more robust." - Stanford News

The EPS conference was a week ago, and many new results and future plans were shown. A good general overview has been collected by Paris Sphicas in his Summary slides. I had a look at some presentations and collected things I personally found interesting. Warning: The selection is heavily biased, I cannot cover everything, and I probably missed many interesting things.

What are even the principles of the theory? Two principles worth considering: The gauge principle: No two different things are ever equal, instead they may be related by a gauge euivalence. Consequently, no two different gauge transformations are ever equal, instead they may be related by a gauge-of-gauge equivalence. And so on.Mathematically this is the principle of homotopy theory...

In this Insight article, Parseval's theorem will be applied to a sinusoidal signal that lasts a finite period of time. It will be shown that it necessarily follows that ## (\frac{\sin(2 x_o)}{x_o})( \frac{\pi}{2})=\int\limits_{-\infty}^{+\infty} \frac{\sin(x-x_o) \sin(x+x_o)}{(x-x_o)(x+x_o)} \, dx ##.

The Hamiltonian in classical mechanics is not always equal to the total energy of the system. I believe this is only true if there is only a potential field and no vector potential. However, in quantum mechanics for a particle in an EM field, even if a vector potential is used the energy operator E -> H. Is this an inconsistency?

About 9% of Germany's power is produced by wood biomass burning, second only to wind in their "renewable" sector. Clearly, wood can be "renewable", but to me the more important question is: is it green? It appears that the EU considers biomass to be "carbon netural" and thus subsidizes it as a clean, renewable energy source. But the situation is not so clear in the US and there is debate about the issue (sources below)...

My understanding: Circuit is ~ 30 million years. Plane of solar system orbit is tilted from plane of milky way.
Is milky way plane crossed once or twice? What is error bar for 30 million? How much does dark matter density vary along solar system path?

Divide each side of a triangle into n equal lengths. Connect the ends of each length to the opposite vertex with straight lines, thereby forming 3n overlapping triangles of equal area. (The problem at the link is an example with n=3.) At how many points will three lines intersect?

Double field theory [1] is an attempt to realize T-duality of string theory at the level of field theory. For instance, if a field in ordinary field theory lives in 4 non-compact space-time dimensions, then a field in double field theory lives in 8 non-compact space-time dimensions. I don't understand it from the physical point of view...

The sleeping beauty problem is a well known problem in probability theory. Allegedly, there are many "thirders" who think that the correct answer is 1/3, but also many "halfers" who think that the correct answer is 1/2. For me, it is quite obvious that the correct answer is 1/3. Is there anybody here who is convinced that the correct answer is 1/2? If you are one of them, what is your argument for 1/2?

Mach, Newton and others observed that centrifugal forces appear in a object when it rotates in relation to the stars. Einstein was convinced by this and tried, unsuccessfully as far as I understand, to incorporate what he called Mach’s Principle into General Relativity...

"Stable beams" has been declared. Similar to 2016, the initial collision rate is low (0.2% the design rate). The machine operators have to check that everything works and nothing presents a danger to the machine before more protons can be filled in. It will probably take a few weeks to reach the same collision rates as achieved last year. Meanwhile, the experiments start collecting some initial data...

Recently, I came across an individual who claimed to research AI professionally and who expressed to me the following view after some discussion of various technologies and the rate of advancement of such tech... I would very much love to read what anyone has to say regarding this, and would also greatly appreciate where you think machine intelligence will be in the next 10 year span...

It so happens that last night I was rereading Einstein's famous 1905 paper On the Electrodynamics of Moving Bodies. I think this is one of the most fascinating scientific papers in history, but some people say it's not at all clear. In any case I love reading Einstein's papers. I would be interested in reactions to how Einstein defines time in the first section of this paper. Is it clear? Is it confusing?

Does this really challenge QED? Or does this mean that we miss certain contributions to QED calculations? The authors are speculating "new effects might appear in the interaction of the electron with itself, the vacuum or the nuclear fields in this regime, that is, the hyperfine interaction might be affected by the existence of new particles not included yet in the current standard model and therefore not considered in state-of-the-art...

Why would nuclear energy be better option, I hear a lot of fears from the general public of why it is not safe?
How would someone convince someones fear about the safety of nuclear power, considering what happened in Japan?

For every person who says “I hate science” there is at least one person saying, “I once wanted to be a scientist.” Life keeps a lot of people from following their desires, and a lot of these people go on to be artists or engineers, or… something other than a scientist. Citizen science lets these people fulfill their dream, and lets them contribute to our understanding of the world and the universe around us...

Solar activity has been a love of mine since the early 1970's and am always looking out
for new research info. Some recent studies and lots of computer animations have come up with new understandings of the mechanisms that instigate CME's and other mass ejections from the sun.

For several years, I've been seeing mention of growing number of residential fuel cells in Japan. But in the USA and the EU, hardly a mention. Does anyone know why the puzzling discrepancy?

I have a reversible chemical reaction described by the balanced equation: ##aA+bB=cC+dD##. I devise a reversible process to take a closed system containing these species (and its surroundings) from thermodynamic equilibrium state 1 to thermodynamic equilibrium state 2...

A major impediment to curing patients with HIV is the fact that the virus integrates its DNA into the genome of the cells it infects. While antiretroviral drugs and therapies can prevent infection of new cells and kill cells that are actively producing virus, a "latent reservoir" remains that can be cause an active infection to re-emerge after drug treatment has stopped. Therefore, current treatments for HIV-infected individuals requires...

I recently read ' Life on the Edge" by Jim Al-Khalili and Johnjoe McFadden. It was very readable and it got me quite convinced about the whole idea. Al-Khalili is a very presentable broadcaster / writer and offers an attractive case. But it was written some while ago and Google hasn't much to offer... I would love to read some well informed opinions about this.

Undergrads struggle with research ideas, because they often tend to assume their work needs to be within the domain of new fundamental science of the sort that would be suitable for the Physical Review, when often their skills and scientific maturity have not yet really empowered them for that level of contribution. As mentors of a lot of undergrad (and high school) research, we’ve found that...

"This chess problem - originally drawn by Sir Roger Penrose - has been devised to defeat an artificially intelligent (AI) computer but be solvable for humans. The Penrose Institute scientists are inviting readers to workout how white can win, or force a stalemate and then share their reasoning."

I've been following, albeit loosely, the use of big data to refine astronomical data. It has been frequently noted that astronomy is an excellent test ground for big data approaches. I'm led to wonder what kind of results have been achieved to date and how effective are these methods for detecting bias in data sets such as foreground contamination? Can it be used to test the parameter space of assumptions applied to data sets?

Time to think about what you can personally do to be a good steward of our home Earth. What activities are you doing today? I will pick up trash I find in my community during my dog walk. I will also be planting some flowers. Oh and patching some holes in my lawn with white clover. It's good for the bees!

A triangle has vertices ##A##, ##B## and ##C##. Mark points ##A',B',C'## on edges ##\overline{BC},\overline{CA},\overline{AB}## respectively so that each is one third of the way along the edge, as shown in the diagram. The lines ##\overline{AA'},\overline{BB'},\overline{CC'}## intersect at points ##A'',B'',C''## and form a triangle inside triangle ##ABC##...

Something curious is going on with these decays. LHCb gives a seminar talk Tuesday next week, a livestream will be available. I'll summarize the current status here. I tried to keep most at the advanced (I)-level, but I don't think that always worked. (B)-level summary: We might have found signs of new unexpected physical effects, but the situation is still unclear...

What do people think of this paper? If I understand correctly, they are saying that the need for Λ disappears if we do N-body simulations that properly take account of GR. I think they are saying that past simulations have used Newtonian approximations that don't properly account for density fluctuations. Can this be? If true, it seems like a major advance. Comments?

Quantum Mechanics(QM) is one of the greatest intellectual achievements in human history. Not only because it describes the world at the microscopic level and in turn provides us with the technological advancement that we enjoy today, but also because it shows us how little we know about the world we’ve been living in for so long....

In the early 1960s, Hermann Bondi advocated a presentation of special relativity (called the k-calculus [which involves no calculus–just simple algebra]) that is advertised to be a “simple logical extension of well-known Newtonian ideas, without any of its mathematical trappings.”

I'd like to know if it's physiologically possible for a human being to be unable to have fever. A related person to me claims that he has never experienced fever in his life, even during influenza, pneumonia and other infections. Is there any similar case of immunodeficiency registered in the medical literature?

The photoelectric effect is usually presented as an example disproving classical electromagnetism as viable model for interaction of light with matter and as evidence of quantization of energy in the electromagnetic field, i.e. the existence of photons. I would like to discuss a thought based on non-relativistic quantum mechanics w/o and relation to Planck, Einstein etc. showing - imho - why this is not so straightforward.

In this paper the following arguments are given why the horizon problem is a fake problem. It raised by me the following question: Why is it assumed in the formulation of the horizon problem that the observed thermal equilibrium from the CMB has to be explained by thermalization right after t=0?

One of the most frequent questions we get is the process and background of being a physics major. Often, we have students asking what are the requirements of obtaining a physics degree, and what can one do with such accomplishments. I am hoping that, in a series of postings on this topic, we get to go over and demystify the whole process of what one can expect...

"Most textbooks attribute cancer-causing mutations to two major sources: inherited and environmental factors. A recent study highlighted the prominent role in cancer of replicative (R) mutations that arise from a third source: unavoidable errors associated with DNA replication."

I'm sure we have all seen the frequent questions from students who don't understand the difference between potential and voltage in a circuit. They seem to think that zero voltage has physical significance. Even using the phrase "voltage drop" is not sufficient, because they say, "What happens when it drops to zero," leading to the concept that voltage is a consumable...

Snow flakes are highly structured, they form from water vapor which has very little structure. I must be misunderstanding entropy, my interpretation of it is that isolated system must evolve into more chaotic less structured states, which is not what happens with snow flakes. Can someone explain?

Plain old standard model baryons, but 5 at the same time, and with crystal clear peaks in the decay to ##\Xi_c^+ K^-##. Each peak in the figure is a particle never seen before, and the significances of those peaks are about 20 sigma (10 sigma for the 5th one). A broad 6th state might hide around 3200 MeV...

A rectangle is divided into a finite number of sub-rectangles. The sides of the sub-rectangles are all parallel to sides of the large rectangle. Each sub-rectangle has at least one side with integer length. Prove that the large rectangle also has at least one side with integer length.

And we can watch different related species at different steps in the transition. In this case, the reason is not the availability of food, but the lower number of predators on land. "At low tide, blennies are commonly found swimming in rock pools around the edges of the island. But when high tide moves in, they climb up to dry land and shuffle around the rocks until the tide retreats. The researchers found that this is most likely..."