The power of math: 17 Equations That Changed the World - a one table summary of the book by Ian Stewart FRS. Business Insider gives its interpretation of the importance of each equation. Brain pickings (2012) on this book and equations, and another extract from the book. [more inside]
A Black Hole Mystery Wrapped in a Firewall Paradox - "A paradox around matter leaking from black holes puts into question various scientific axioms: Either information can be lost; Einstein's principle of equivalence is wrong; or quantum field theory needs fixing." [more inside]
A five-part series on the ultimate limit on technology, and how that limit could help us find other civilizations: 1 2 3 4 5 [via]
The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
Quantum Mechanics: Myths and Facts (pdf), a recently-updated paper on the Cornell arXiv peer-review site. By Hrvoje Nikolić of the Rudjer Bošković Institute in Croatia. [more inside]
Science sites of all kinds for kids. Archeology. Entomology. Natural Symphony. Baseball in Space. Philosophy. Process or Content. Science songs. Physics songs, relativity. String theory. Science and Art.
The sun is solid (this has beautiful images, btw). The earth is fixed, or maybe growing; relativity is wrong, and so is most of current thinking... For the intriguing as well as the insane, visit the fringes of science.
Does dark matter exist? Dark matter has been suggested as a solution to the galaxy rotation problem where individual stars don't seem to rotate the way Newton's laws would predict. Now, some scientists are saying that observations fit with Einstein's general relativity, without any dark matter needed. I just find it amazing that no one has tried this yet.
Does relativity have any practical significance? In fact, relativity had to be taken into account by the designers of the Global Positioning System. The GPS satellites are affected both by special relativity (since the satellites are moving, clocks aboard them appear to run slower as seen from the ground), and by general relativity (since the satellites are farther away from the mass of the earth, clocks appear to run faster as seen from the ground). The net effect of both is that clocks aboard GPS satellites would gain 38 microseconds per day relative to the ground, if relativistic effects were not corrected for--a figure which can be confirmed by using Google calculator.
In an interesting test of the theory of relativity they found that gravity travels at the same speed as light. Put simply if the sun were to disappear from existence it would take some 8 minutes before the Earth's orbit would be affected by the loss. Sadly this also means that FTL travel is becoming less and less likely to be possible.