The first galaxies in the Universe probably played a major part in reionization—the event in which primordial gas was turned into a plasma. However, observations of this era are very hard: we’re looking back in time to when the first stars formed, over 95% of the total age of the Universe. As a result, the new discovery of a possible galaxy from 500 million years after the Big Bang is significant…and based on how they found it, its discoverers think it might be just one of many such galaxies.
The astronomers observed 12 galaxy clusters in a small region of the sky. Galaxy clusters are the most massive objects in the Universe bound together by gravity, so they are capable of being powerful gravitational lenses—distorting space in a way that magnifies the light from still more distant objects. The researchers found an object in the region of the galaxy cluster MACS J1149+2223 that appeared to correspond to a magnified galaxy. [Read more….]
The test rig for DECam, which I saw when I visited Fermilab in May.
I had the privilege of visiting Fermilab in May, as part of my research for my book-in-progress. While I was there, I got to see the test rig for the Dark Energy Camera (DECam), which looks like something from Stargate or the wormhole entrance from Contact. Unfortunately for me, the camera itself had already been shipped to Chile, but yesterday DECam released its first images to the public. Here’s my story, written for Ars Technica:
DECam is mounted on the Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile, where dark energy was first observed in 1998. As the name indicates, it is a camera, albeit a far more sensitive one than is available to consumers. The business end of the camera is a set of 62 charged-coupled devices (CCDs), yielding images of 570 megapixels. [Read more….]
My latest post at Galileo’s Pendulum tests a way to explain quantum field theory to non-scientists, which I hope to put in my book-in-progress. Please go read the post, and let me know what you think!
Just as a ship moving through still water produces a wake, electrons create ripples in the ambient electromagnetic field. Those ripples are largest close to the electron and taper off over larger distances, becoming effectively zero. If another electron is nearby, the ripples they make will push the two particles apart. This is the quantum field version of the elementary school physics principle we all learned: “like electrical charges repel”. However, there’s a lot more going on! The ripples take time to travel between the electrons, so the interaction isn’t instantaneous. Also, they aren’t smooth waves like you get in water: they are themselves made of particles—specifically photons, particles of light. [Read more...]
If you (like me) have ever been in charge of buying and/or maintaining lab equipment, you might have griped about its cost, or your inability to repair it. A new DIY movement based on open-source hardware and software could allow for the relatively inexpensive fabrication of laboratory equipment. My latest for Ars Technica has the story:
Imagine a world where lab workers can create their own custom equipment in-house, using either their own designs or ones they’ve downloaded. A glimpse of that world appears in today’s issue of Science, provided by 3D printing, the relatively low-cost fabrication technique where ceramics, polymers, and other materials are deposited in layers to build up a three-dimensional shape. [Read more…]
The Heisenberg Uncertainty Principle is one of the most important results in quantum theory, dealing with limitations of accurate measurements on two complementary quantities. However, there is a misconception (dating from Heisenberg himself) that the act of measurement is what causes the uncertainty. A new experiment has demonstrated that view is wrong, as I explain in my most recent Ars Technica article.
One of the most important—and famous—results in quantum mechanics is the Heisenberg Uncertainty Principle (HUP). What is less known (at least to non-physicists) is that the HUP exists in two versions. Werner Heisenberg’s original formulation stated that the act of measurement disturbs a physical system, placing strong constraints on (for example) the simultaneous measurement of both the position and momentum of a particle. A more mathematically rigorous version places inherentlimits on the measurement of physical quantities—independent of whether any measurement is actually performed.
While it is often assumed that these different formulations are the same, recent theoretical results have shown the original Heisenberg measurement-based version is incomplete. [Read more!]
Over the last year, I’ve become very involved with the Science Online community. This is a group focused around an annual (un)conference, whose purpose is the communication of science through electronic media. Here’s an interview I did with Bora Zivkovic, one of the leading figures in the Science Online community. Key excerpt:
I still think of myself as an educator even now, though I’m no longer in the college classroom. I want to share the wonder of physics to those who think of it as something beyond them, or even something to fear. In this era when the very goals of education are being challenged (at least for the children of poor and working-class families), it seems more important than ever to stress the importance of science, not just in daily lives, but in our intellectual structure. Science can be a source of joy and wonder for everyone, whether they are scientists or not.