Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!
Physics Forums Featured Threads

Fish becoming landdwellers today
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..." 
Specifications for elephantresistant steel poles
I have camera traps out on the African bush, that are monitoring the responses of leopards to artificial scents. The cameras are in steel boxes to protect them from elephants, the boxes are bolted to brackets 150 mm long and the brackets are bolted to steel poles at a height of either 500 or 700 mm above ground level. The poles are 40 x 40 mm mild steel angle, either 2mm or 3mm thickness... 
Math Challenge by QuantumQuest #1
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)##. 
What is the Quantum of Sound in Gases and Air
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? 
Math Challenge by Charles Link #1
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. 
Why is Hilbert not the last universalist?
It is often said that Poincare was the last universalist, i.e. the last mathematician who understood moreorless 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? 
Is the US abandoning its position as a science superpower?
"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. 
Can modern physics be understood qualitatively?
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... 
Are there really 4 fundamental math operations?
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. 
Do patents inhibit development in the technology?
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... 
Is Reverse Engineering Ethical?
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. 
Can a space vessel generate its own photon wind?
In a nutshell, does Newton's "action = reaction" law apply to massless particles? If a spaceship directs a condensed light beam on its own heatresistant photon sail, what would happen? 
Problem with science today and the war on reason
"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 
NASA press conference: Exoplanets around TRAPPIST1
Yes, 7 planets around TRAPPIST1, all about Earthsized 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?). 
A possible solution to the cosmic lithium problem
This paper; Nonextensive 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...
Page 16 of 21