The world’s largest space camera’s first test subject? Broccoli.
Construction is nearly complete for a camera that will take 3,200-megapixel panoramas of the southern night sky.
This camera takes colossal digital pictures. It would take 378 4K ultra-high-definition televisions to display just one of them at full size. So what kind of test picture might one take with such a beast? Well, a head of broccoli, of course.
The world's largest digital camera for astronomy captures 3,200-megapixel images. It's destined to photograph panoramic views of the night sky in unprecedented detail for the Legacy Survey of Space and Time (LSST) database at the Vera C. Rubin Observatory in Chile, 8,700 feet above sea level atop Cerro Pachón. Right now, people at the Department of Energy's SLAC National Accelerator Laboratory are finishing up its construction. The exquisitely detailed broccoli portrait was taken in January 2020 as a test of the camera's focal plane.
Everyday produce notwithstanding, project manager Vincent Riot says that, "this is a huge milestone for us. The focal plane will produce the images for the LSST, so it's the capable and sensitive eye of the Rubin Observatory."
Building a bigger focal plane
The tech involved in the focal plane is incredibly sophisticated and its assembly is downright harrowing.
The sensors that capture 16-megapixel images in high-end digital cameras are called charge-coupled devices, or CCDs. (Our phones and tablets instead use CMOS sensors.) The LSST camera contains 189 CCD sensors. The sensors are arranged into 21 squares of nine CCDs each — each square is called a "science raft." The 2-foot-tall, 20-pound rafts are mounted in a grid inside the camera. This all adds up to 3.2 billion pixels, each of which is tiny at 10 microns in size, about a tenth of the width of a human hair.
As you might expect, assembling such sophisticated hardware is not for the faint of heart. The rafts must be precisely positioned in the grid so that they're separated by a width equivalent to just five human hairs. If they touch they crack, and down the drain goes $3 million per raft. The SLAC team practiced the assembly operation for a year before the six-month assembly process commenced.
One CCD raft in place, plus a smaller non-imaging raft to its left.
Amazingly detailed images
The camera will be worth the effort.
The flatness of its giant focal plane — over 2 feet wide, as opposed to 1.4 inches in a consumer camera — will allow it to capture images of the heavens about 40 moons across. Zoomed in, the team says an image it produces will be so clear it will be like seeing a golf ball from 15 miles away. The camera will also be highly sensitive to dim objects, so it will be able to take pictures of things that are more than 100 million times dimmer than what we can see with our eyes — it's comparable to being able to see a candle from 1,000 miles away. Project scientists Steven Ritz sums it up: "These specifications are just astounding."
Once assembled, the focal plane was put inside a custom-built cryostat for cooling — the required operating temperature is -150° F.
Broccoli, say "cheese."
Broccoli's surface is packed with tiny details, making it a sensible candidate for testing out the focal plane. The camera housing hasn't yet been completed, so the scientists created a pinhole device that projected the broccoli's image onto the focal plane.
The man in charge of assembling and testing the LSST focal plane is Aaron Roodman, who says that "taking these images is a major accomplishment. With the tight specifications we really pushed the limits of what's possible to take advantage of every square millimeter of the focal plane and maximize the science we can do with it."
(Click image to explore the image at full resolution.)
Next up for the SLAC team is moving the cryostat/focal plane structure into the actual camera body along with the camera's lens assembly, which is also remarkable — it's the world's largest optical lens. The three-lens array was built by Ball Aerospace and Arizona Optical Systems and (carefully) driven 17 hours from Boulder, Colorado to SLAC 's Menlo Park, New Jersey facility.
"Nearing completion of the camera is very exciting," says JoAnne Hewett, SLAC's chief research officer. "And we're proud of playing such a central role in building this key component of Rubin Observatory."
The LSST camera's mission is to take one complete, incredibly detailed panoramic image of the Southern sky per day for 10 years. Adds Hewett, "It's a milestone that brings us a big step closer to exploring fundamental questions about the universe in ways we haven't been able to before."
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The idea of 'absolute time' is an illusion. Physics and subjective experience reveal why.
- Since Einstein posited his theory of general relativity, we've understood that gravity has the power to warp space and time.
- This "time dilation" effect occurs even at small levels.
- Outside of physics, we experience distortions in how we perceive time — sometimes to a startling extent.
Physics without time<p>In his book "The Order of Time," Italian theoretical physicist Carlo Rovelli suggests that our perception of time — our sense that time is forever flowing forward — could be a highly subjective projection. After all, when you look at reality on the smallest scale (using equations of quantum gravity, at least), time vanishes.</p><p style="margin-left: 20px;">"If I observe the microscopic state of things," writes Rovelli, "then the difference between past and future vanishes … in the elementary grammar of things, there is no distinction between 'cause' and 'effect.'"</p><p>So, why do we perceive time as flowing <em>forward</em>? Rovelli notes that, although time disappears on extremely small scales, we still obviously perceive events occur sequentially in reality. In other words, we observe entropy: Order changing into disorder; an egg cracking and getting scrambled.</p><p>Rovelli says key aspects of time are described by the second law of thermodynamics, which states that heat always passes from hot to cold. This is a one-way street. For example, an ice cube melts into a hot cup of tea, never the reverse. Rovelli suggests a similar phenomenon might explain why we're only able to perceive the past and not the future.</p><p style="margin-left: 20px;">"Any time the future is definitely distinguishable from the past, there is something like heat involved," Rovelli wrote for the <a href="https://www.ft.com/content/ce6ef7b8-429a-11e8-93cf-67ac3a6482fd" target="_blank"><em>Financial Times</em></a>. "Thermodynamics traces the direction of time to something called the 'low entropy of the past', a still mysterious phenomenon on which discussions rage."</p>
The strange subjectivity of time<p>Time moves differently atop a mountain than it does on a beach. But you don't need to travel any distance at all to experience strange distortions in your perception of time. In moments of life-or-death fear, for example, your brain would release large amounts of adrenaline, which would speed up your internal clock, causing you to perceive the outside world as moving slowly.<br></p><p>Another common distortion occurs when we focus our attention in particular ways.</p><p style="margin-left: 20px;">"If you're thinking about how time is <em>currently</em> passing by, the biggest factor influencing your time perception is attention," Aaron Sackett, associate professor of marketing at the University of St. Thomas, told <em><a href="https://gizmodo.com/why-does-time-slow-down-and-speed-up-1840133782" target="_blank">Gizmodo</a></em>.<em> "</em>The more attention you give to the passage of time, the slower it tends to go. As you become distracted from time's passing—perhaps by something interesting happening nearby, or a good daydreaming session—you're more likely to lose track of time, giving you the feeling that it's slipping by more quickly than before. "Time flies when you're having fun," they say, but really, it's more like "time flies when you're thinking about other things." That's why time will also often fly by when you're definitely <em>not</em> having fun—like when you're having a heated argument or are terrified about an upcoming presentation."</p><p>One of the most mysterious ways people experience time-perception distortions is through psychedelic drugs. In an interview with <a href="https://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview" target="_blank"><em>The Guardian</em></a>, Rovelli described a time he experimented with LSD.</p><p style="margin-left: 20px;">"It was an extraordinarily strong experience that touched me also intellectually," he said. "Among the strange phenomena was the sense of time stopping. Things were happening in my mind but the clock was not going ahead; the flow of time was not passing any more. It was a total subversion of the structure of reality."<br></p><p>It seems few scientists or philosophers believe time is completely an illusion.</p><p style="margin-left: 20px;">"What we call <em>time</em> is a rich, stratified concept; it has many layers," Rovelli told <em><a href="https://physicstoday.scitation.org/do/10.1063/PT.6.4.20190219a/full/" target="_blank">Physics Today</a>.</em> "Some of time's layers apply only at limited scales within limited domains. This does not make them illusions."</p>What <em>is</em> an illusion is the idea that time flows at an absolute rate. The river of time might be flowing forever forward, but it moves at different speeds, between people, and even within your own mind.
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Controversial physics theory says reality around us behaves like a computer neural network.
- Physicist proposes that the universe behaves like an artificial neural network.
- The scientist's new paper seeks to reconcile classical physics and quantum mechanics.
- The theory claims that natural selection produces both atoms and "observers".
Vanchurin interview:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="539759cbfd8fcd5b6ebf14a3b597b3f9"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/bmyRy2-UhEE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Vanchurin on “Hidden Phenomena”:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="18886ffd5e5840bb19d4494212f88d82"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/2NDVdNwsHCo?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>Vitaly Vanchurin speaking at the 6th International FQXi Conference, "Mind Matters: Intelligence and Agency in the Physical World." The Foundational Questions...
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