kw: book reviews, nonfiction, science, astronomy, serendipity
To abbreviate a saying usually attributed to Isaac Asimov: Science begins with the phrase, "Hmm, that's funny!"
I once worked as a machinist at Cal Tech, often in the big room where the mirror for the Palomar Telescope was formed and polished decades earlier. Later half the room was taken over to build an early synchrotron (atom smasher), which had been disassembled but big concrete rings remained. Also, a cabinet in a corner of the room was filled with manuscripts of experiments that had been performed using the synchrotron, often attached to copies of PhD dissertations, which indicated the student had been awarded the degree. We were assembling an innovative radio telescope in the room, and its reflective surface was being machined semi-automatically. I had to be present to monitor and adjust the machinery, listening for anomalies in the process. During chunks of semi-free time I read here and there in the manuscripts. I found that many of the students using the synchrotron had eventually proved their original idea to be incorrect, but had discovered something else along the way, so they got their Doctorate anyway. Scientific serendipity at work!
In nine chapters Professor Lintott leads us through the history of several important discoveries. One amazing example is the Hubble Deep Field. Several astronomers took a big risk and managed to convince the folks in charge of the Hubble Space Telescope to have it point towards a spot in space near the Big Dipper, where nothing could be seen on earlier photographs of the sky. For four days!
This is part of the result; it is about a quarter of the whole image, which included an area of sky about 0.6% the area of the Moon. Thus this image is about 0.15% of the Moon's apparent area.
This is at 1/3 the scale of the original image, so each pixel here is the average of 9 original pixels. I darkened the background to get rid of very low-level jitter. Just left of center, the bright white item with spikes is a star. Near top center is a dimmer, more yellowish star. Both stars are too dim to be seen by most telescopes. Besides these two stars, everything else in this image bigger than a single pixel is a galaxy. Hundreds are shown here, and nearly 2,000 galaxies have been enumerated in the entire full-scale image. Each galaxy contains billions to hundreds of billions of stars.
This Deep Field image triggered deeper and deeper-field images, because the longer a telescope records the light from an area, the more stuff is seen. More recent work with the James Webb Space Telescope (hereafter JWST), including infrared deep fields, shows that we can record information for at least a few trillion galaxies in the visible universe. The tiniest (apparently tiniest!), and thus farthest, galaxies shown may be at a distance of 12-13 billion light-years, showing us what things were like when the Universe was one or two billion years old.
For "older" light than that, we must rely on microwaves. The continuing expansion of the cosmos means that older light has been red-shifted, and at 12.5 or 13 billion years back, any "light" that could be visible here and now has been red-shifted to far infrared or even to microwaves. We have pigeon droppings and the unstoppable determination of two scientists to thank for first recording those microwaves, depicted here over the whole sky:
The features of this image are the highly amplified variations in a generally uniform radiation field, over the whole sky, that is characteristic of a blackbody with a temperature of 2.73K, or -270.42°C or 454.8°F. This corresponds to a peak microwave frequency of about 160 GHz, a wavelength of about 1.9 mm. This can be compared to the microwaves in your microwave oven, with a frequency of 2.45 GHz and wavelength of 120 mm.
In 1964 Arno Penzias and Robert Wilson weren't looking for anything astronomical. They were trying to reduce the noise in a large antenna being used to bounce signals off the Echo satellite. At one point, they evicted a nesting family of pigeons and cleaned out the droppings. That did reduce the noise, but some remained. The "stray" signal was eventually found to be coming from literally every direction at the same frequency range and intensity. That meant it was not on Earth, and probably outside the Solar System, or even the Milky Way galaxy. It is actually "light" (originally X-rays and gamma rays) that was emitted when the age of the universe was about 360,000 years, red-shifted to microwave radio frequencies.
The features of the image above represent variations of only 0.01% of the total intensity. They were measured by spacecraft, because there are too many noisy microwave emitters on Earth.
I love astronomy, and I could go on and on, but I'll leave it to you to read the book. We haven't found solid evidence of aliens, visiting or elsewhere, but that would be the biggest discovery of all. And I suspect further serendipity will lead to it.
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