Light speed

We are stuck on the idea that 300,000 kilometres a second is a speed limit, because we intuitively believe that time runs at a constant universal rate. However, we have proven in many different experimental tests that time clearly does not run at a constant rate between different frames of reference. So with the right technology, you can sit in your star-drive spacecraft and make a quick cup of tea while eons pass by outside. It’s not about speed, it’s about reducing your personal travel time between two distant points. And that has a natural limit – of zero.

A decent little tutorial. One approach that can also be used is to note that the invariant speed, given by the velocity four-vector, has a constant length of c. The three spatial components are the velocity and the time component is \(gamma\)ct. If you are stationary, as we all are in our own rest frame, time ticks normally. But when one is moving — the spatial velocity vector is nonzero — the time component of the vector shortens compensates.

Update: Chad points out some sloppiness on my part. The vector is given by \({v_x}^2+{v_y}^2+{v_z}^2-gamma c^2\) so the components get bigger while the resultant stays constant.

Opinion: Charles Krauthammer: The neutrino that rocked the universe

If quantum mechanics were a challenge to human sensibilities, this pesky Swiss-Italian neutrino is their undoing. It means that Einstein’s relativity — a theory of uncommon beauty upon which all of physics has been built for 100 years — is wrong. Not just inaccurate. Not just flawed. But deeply, fundamentally, indescribably wrong.

Sigh. Charles Krauthammer is deeply, fundamentally, (but possibly) describably wrong. This shows a very basic misunderstanding of the process of science — the same class of misunderstanding in which people than that popular opinion drives science, or that deciding on a truth and then looking for evidence to support it (and ignoring the contradictions) is science.

There are different kinds of wrong. The things that are deeply, fundamentally, indescribably wrong are flat-out abandoned. The luminiferous aether was fundamentally wrong — there is no preferred reference frame for the universe. Classical physics is wrong, too, but 1/2 mv^2 is still used as a formula for kinetic energy and it works as long as the speeds are much smaller than that of light. In another area of relativity we know that Newton’s law of gravitation is wrong as well, but it’s good enough to send spacecraft to the moon and other planets. This is science: we quantify wrong, and there’s a difference between not correct and there’s a discrepancy in the nth decimal place. Even if the neutrino data turns out to be correct, it will require a modification of relativity, not an abandonment of it. GPS signals — intimately dependent upon both gravitational and kinematic effects of relativity — are still be able to give you your location, something I checked empirically this past weekend. Relativity works in so many situations; it’s not wrong in that regard.

It would be exciting if this ends up being correct, but it will not end with us kicking relativity to the curb — it will give us new physics in addition to the physics we have, rather than instead of the physics we now have. Any new theory will look just like relativity under the situations we’ve already tested. Charles Krauthammer writes mainly about politics. He should stick to his day job.

Diffraction With Infrared Light

… and visible light, too.

Faster than a speeding photon? Precursors test whether light can be faster than light

While we wait [for neutrino analysis], it is worth noting that in June 0f 2011 a group of researchers performed an experiment to see if light itself could move faster than light! In particular, the scientists used a little known optical phenomenon known as an optical precursor to see if individual photons might travel faster than while propagating in a material. In the end, the experiment suggests that these single photons did not in fact violate Einstein’s speed limit, though the results still got a significant amount of press.

Feast your eyes on a complete quadruple rainbow

Each extra reflection inside a raindrop produces a different rainbow. Each reflection dims the ray a little bit more, such that higher order rainbows not only become progressively fainter and difficult to see, they also switch what side of the sky you see them on

Laser light used to cool object to quantum ground state

For the first time, researchers at the California Institute of Technology (Caltech), in collaboration with a team from the University of Vienna, have managed to cool a miniature mechanical object to its lowest possible energy state using laser light. The achievement paves the way for the development of exquisitely sensitive detectors as well as for quantum experiments that scientists have long dreamed of conducting.