Viruses are infectious, tiny and nasty. But are they alive?
Not really, although it depends on what your definition of “alive” is, two infectious disease doctors told Live Science.
Living beings, such as plants and animals, contain cellular machinery that allows them to self-replicate. In contrast, viruses are free forms of DNA or RNA that can’t replicate on their own. [What If We Eradicated All Infectious Disease?]
Rather, viruses need to invade a living organism to replicate, said Dr. Otto Yang, a professor of medicine and microbiology, immunology and molecular genetics at the David Geffen School of Medicine at the University of California, Los Angeles.
“[Viruses are] packaged RNA or DNA,” Yang told Live Science. “They make more copies of themselves by hijacking the machinery of cells to replicate themselves.”
Is it alive?
Countless philosophers and scientists have debated how to define whether something is alive. According to the seven characteristics of life, all living beings must be able to respond to stimuli; grow over time;produce offspring; maintain a stable body temperature; metabolize energy; consist of one or more cells; and adapt to their environment.
However, some life-forms don’t fit every single characteristic. Most hybrid animals, such as mules (a cross between a donkey and a horse), can’t reproduce because they are sterile. Moreover, rocks can grow, albeit in a passive way, with new material flowing over them. But this classification problem goes away when a simpler definition of “life” is used.
“Take a cat, a plant and a rock, and leave them in a room for days,” said Amesh Adalja, an infectious disease physician and an affiliated scholar at the Johns Hopkins Center for Health Security in Baltimore. “Come back, and the cat and the plant will have changed, but the rock will essentially be the same,” he said.
Like a rock, most viruses would be fine if they were left indefinitely in a room, Adalja said. In addition, he noted that living beings have self-generated and self-sustaining actions — meaning they can seek out sustenance and behave in self-preserving ways. In other words, “they’re taking actions to further their lives, [such as] a plant sprouting its roots to find water or an animal looking for food,” Adalja said.
Something that is not alive, such as a virus, does not have self-generated or self-sustaining actions, he said.
“I don’t think viruses qualify as being alive. They are, in essence, inert unless they come into contact with a living cell,” Adalja said. “There are some characteristics of viruses that put them on the borderline [of being alive] — they have genetic material: DNA or RNA. It’s not the same thing as a rock, but it’s clearly not the same thing as even bacteria, in terms of that self-sustaining and self-generated action.” [Could Humans Live Without Bacteria?]
Yang agreed, saying, “Without a cell, a virus cannot reproduce. And so from that standpoint, it’s really not alive, if you consider life to be something that can reproduce by itself independently.”
However, “if you loosen up your definition of life to something that can make copies of itself with help, then you could call it alive,” Yang said.
It’s thought that some of the very first life-forms on Earth were RNA molecules, as “RNA molecules, under the right conditions, can make copies of themselves,” Yang said. “Viruses maybe evolved from that ancestor, but lost the capability to self-replicate.”
Over centuries, humans have left a widening imprint on this planet, marked by a growing need for natural resources, and by the rapid expansion of agriculture and infrastructure. And a new study has found that one of the hallmarks of this footprint is the appearance of 208 species of minerals that exist solely due to human activity. These minerals represent nearly 4 percent of the 5,200 mineral species recognized by the International Mineralogical Association (IMA), and most can be attributed — directly or indirectly — to mining in locations around the world, forming as a direct result of their rocky environment’s uniquely human-made conditions. [Photos: The World’s Weirdest Geological Formations] Many of the minerals that were linked directly to mining formed within the mines themselves, in dumps for mining by-products or on mining-related artifacts, with some dating as far back as the Bronze Age, the study authors reported. And other minerals emerged naturally but from human-made objects: bronze artifacts in Egypt, tin artifacts in Canada, and lead artifacts in a Tunisian shipwreck. Earth’s history is marked in periods of time known as epochs, which are defined by notable changes in the geologic record. The current epoch, the Holocene, launched about 12,000 to 11,500 years ago, after the end of the Paleolithic Ice Age, but geologists have proposed the introduction of a new epoch called the Anthropocene to characterize a recent period in Earth’s history, dating back about two centuries ago. The Anthropocene indicates the first appearance of evidence for people shaping permanent geologic changes, such as the large-scale removal of rock and sediment, the widespread redistribution of gemstones and mineral specimens, and the global appearance of novel minerals associated with human activity.
According to the new study, the catalog of 208 minerals that exist solely due to human activity represent a clear dividing point in Earth’s history — before human activity and after. This impact is expected to last “far into the future,” the study authors wrote. And due to the rapid pace of the new minerals’ formation and the likelihood of many more continuing to emerge, their appearance is described by the scientists as equal in significance to — if not greater than — the so-called Great Oxidation event billions of years ago, when the influx of oxygen in Earth’s atmosphere spurred the development of about two-thirds of all known minerals. “Simply put, we live in an era of unparalleled inorganic compound diversification,” study co-author Robert Hazen, a research scientist at the Carnegie Institution of Washington’s Geophysical Laboratory and a professor of Earth Science at George Mason University in Virginia, said in a statement. “Indeed, if the Great Oxidation eons ago was a ‘punctuation event’ in Earth’s history, the rapid and extensive geological impact of the Anthropocene is an exclamation mark,” Hazen added. The findings were published online March 1 in the journal American Mineralogist. Original article on Live Science.
The northwest Chinese city of Lanzhou has a serious water shortage problem. To address the issue, its urban planners have sketched out an ambitious plan to deliver water from Siberia’s Lake Baikal to the city along a 1,000-mile-long pipeline. Getting approval for the project will be a monumental challenge, but it may be a sign of things to come for other water-poor regions of the world.
Lake Baikal is the largest freshwater lake in the world by volume, containing roughly 20 percent of the world’s unfrozen surface water. The pipeline would extend for 1,068 miles (1,720 km) along the Hexi Corridor, a desert region that runs between the Tibetan Plateau and the Gobi Desert. The pipeline would cut a swath straight through Mongolia.
The Lanzhou planners say the chronic water shortage is stunting the region, which experienced just 15 inches (380 mm) of rain last year.
“The pipeline will boost the utilization rate and business prospects of [Gansu province], improve the ecological environment of Northwest China, and promote Lanzhou’s economic growth,” the authors wrote in the proposal, titled “Vision for Urban Planning 2030.”
The proposal is calling attention toChina’s ongoing water shortages. The country has 20 percent of the world’s population, but only 7 percent of its fresh water. Back in 2005, China’s former minister of water resources warnedthat many northern cities, including Lanzhou, would run out of water by 2020.
Unsurprisingly, the Lanzhou plan has been met with criticism. Some are questioning the feasibility of the plan, citing the tremendous costs involved, and the difficulties of coordinating the countries and local jurisdictions involved.
“To declare the global plans of the transfer of fresh water to China, without detailed calculations, is total folly,” noted environmentalist and economist Viktor Danilov-Danilyan told the Siberian Times. “It would require big funds and the price of the water will be very high. Almost certainly this project is simply unprofitable.”
That said, Russia may be willing to entertain the idea. A year ago, Russia’s agriculture minister proposed a similar pipeline between Kazakhstan and Xinjiang, saying it would only happen “under the condition of full compliance with the interests of Russia, including environmental.” The Russian petro-state—i.e. a country with an economy largely driven by its oil and gas interests—with its abundance of fresh water, may be willing to capitalize on its commodities even further, becoming the world’s first hydro-state.
“Water is the same resource as oil, gas, gold, and sooner or later we will start to sell it,” noted Stepan Svartsev from Tomsk State University in the Guardian.“Our country has very large reserves and certain volumes could be sold.”
In addition to the political and diplomatic hurdles, there’s also the environment to consider. An environmental impact assessment would have to be conducted along the 1,000 mile corridor. The effects of the pipeline on Lake Baikal would also have to be addressed. This source of fresh water is a haven for 1,200 animal species and 600 types of plants, of which half are local to the region.
It’s also important to point out that Lake Baikal is already facing severe environmental problems. Once prized for its crystal clean water, scientists say its southern-most areas have become inundated with algae, making it unsafe to drink. Surface runoff of nutrients into the lake, plus warming conditions, are allowing the algae to thrive. Adding insult to injury, water levels have dropped in recent years, and residents near the lake have already been told to cut down on water usage.
Certinaly, it’ll be interesting to see how this story plays out. The proposal from Lanzhou may be rejected, but that doesn’t mean other pipeline plans won’t work out, both in China and abroad.
Or more practically, we should push for industrial-scale desalination. Approximately 97 percent of the world’s water is tied up in our oceans, but we can’t drink it. Should gains in solar power efficiency continue, we should start to see the first large-scale desalination plants appear by the 2030s.
My first question was, “What is a time crystal?” Harvard graduate students Soonwon Choi, Joonhee Choi and postdoctoral researcher Renate Landig all started laughing. “That’s a very good question,” said Soonwon. The time crystal’s silly science fiction name shrouds its deep quantum mechanical nuance. Sometimes a name is simply the easiest approximation to describe something far more complex than inquiring minds can conjure.
Two groups of scientists report that they’ve observed exotic time crystals, systems of atoms whose properties arrange themselves, or “crystallize” in time like the way solids can crystallize in space. The two groups’ vastly different atomic arrangements aren’t perpetual motion machines, weapons, or time travel devices—but their strange behavior sheds light on a whole new class of materials with properties different from any solid, liquid or gas you’ve ever encountered.
“The experiments are beautiful and open up a new class of states of matter that really qualitatively are new and fascinating in their own right,” MIT theoretical physicist and Nobel laureate Frank Wilczek told Gizmodo. Wilczekproposed time crystalsin 2012, while wondering whether certain properties changingin time, rather than in space, could yield new phases of matter. He said “the new discoveries… are certainly a recognizable descendant of the original vision and have retained the name.”
Physical laws are laden with symmetries—instances where an action produces the same reaction in a different environment. If you punch a solid wall with the same force, it will hurt equally no matter where along the length of the wall you punch it or what time of day it is—those are spatial and time translation symmetries. Some symmetries can break. Crystals, solids where particles arrange themselves in a lattice, break a so-called spatial translational symmetry, since the molecules prefer a specific place in space. If you had a picket fence instead of a solid wall, that might break a spatial translational symmetry, since punching a picket feels different than punching the space between planks.
Wilczek’s idea was simple: Can molecules break time translational symmetry? Can certain solids crystallize in time, preferring different states at different time intervals? That question became: Do certain periodic behaviors of a collection of atomshave preferred tempos? This would kind of be like 17-year cicadas—they could come every year, but instead they break a time translational symmetry, since they clump on the 17th year rather than appearing evenly every year.
Physicists Haruki Watanabe and Masaki Oshikawa from the University of Tokyo realized in 2014 that, no, there probably aren’t time crystals, at least not in the way Wilczek defined them. Two years later, physicists including Shivaji Sondhi at Princeton and Chetan Nayak-from the University of California, Santa Barbara demonstrated that time crystals might exist if youchanged the rules a little bit—by giving atoms a periodic nudge, for example. Physicist Norman Yao at the University of California, Berkeley drafted up a sort of blueprint for what to measure to convince researchers they’d created a time crystal. The discoveries both came out in preprint a few weeks ago, but they have now been vetted via the peer review process.
“The surprising thing about the time crystal is that it’s stable,” Yao told Gizmodo. The time crystal would need to prefer a certain vibrational frequency, different from the frequency of the periodic nudge. Under a few nudges, the preferred vibrational frequency doesn’t change.
That’s what each group is reporting today in the journal Nature. Particles have an innate quantum mechanical property called “spin” related to magnetism, which in the case of these crystals, has two different values. The values all align, and swap back and forth at the time crystal’s preferred tempo. Precisely understanding spin isn’t so important for understanding time crystals—at a really basic level, just think of it like each particle as a spectator at a sports game holding a sign. If everyone holds up side A, the collective signs say one phrase, and if they all hold up side B, it says a different phrase. Otherwise, it’s a garbled mess.
One group at the University of Maryland lined up ten trapped ytterbium ions (ytterbium is just a chemical element) and shined them with periodic laser pulses to mostly, but not completely, flip the ions’ spins. The particles’ spin values snapped into place, completely flipping regardless. They continued flipping and all lining up at half the speed of the laser pulse. If the team altered the pulse a little bit, the ten ions kept with their same cycle, even though intuition says the time crystal’s periodic motion should eventually fall apart. Instead, they preferred to march at the beat of their own drum.
The Harvard group’s setup was a little different. They loaded the regular carbon lattice of a diamond with impurities in the form of nitrogen atoms—so many impurities that the diamond turned black. Their crystal also required a pulsing force, in this case a microwave field, and they also watched the impurities’ spins flip back and forth, snapping into place with their own lower frequency, a longer period. This caused the diamond to fluoresce, like in the picture below. Their system was so complex that the theory doesn’t fully explain the behavior, said Soonwon Choi.
“Both systems are really cool. They’re kind of very different,” said Yao. “I think they’re extremely complimentary. I don’t think one is better than the other. They look at two different regimes of the physics. The fact that you’re seeing this similar phenomenology in very different systems is really amazing.”
The crystal might prefer its spin-switching tempo, but the effect certainly won’t last forever. Time crystals can’t exist without the repeating pulse of energy to coax the atoms to organize in time. “It’s not a perpetual motion machine,” Jiehang Zhang from the University of Maryland told Gizmodo. “We’re driving it!”
If you’re still a little confused, Yao’s got a great boilerplate explanation: If you’re jumping rope, you expect a rotation every time the person holding the rope’s hand spins. These time crystals have taken on a mind of their own—the rope makes a full circle, or the spins cycle, for every two times your hands spin. Furthermore, explained Zhang, jostling the rope a little bit won’t stop or alter the stable spinning.
Nayak agreed both groups presented evidence of the crystals he and others theorized, but we still need to know just how stable these crystals are. “Their combined results point to the need for experiments that truly show that the oscillations remain in phase over extended times,” he wrote in a Nature News & Views article, “and are not washed out by the inevitable fluctuations.”
Now that you know what a time crystal is, your first thought is most certainly “that’s it? What’s so exciting about that?” (“The other day in a game I saw a time crystal as a weapon,” said Landig). Soonwon immediately brought up potential quantum computing applications in the far future, controlling lots of quantum bits at the same time. But, the importance is likely more fundamental. Normally phases of matter exist only by changing the way particles arrange in space. Time crystals open up a whole world of possible new phases of matter by adding these laser or microwave pulses—phases that only exist when you’re doing something to the solid, like a quantum physics version of how corn starch mixed with water only feels solid when you smack it.
“It shows that the richness of the phases of matter is even broader [than we thought],” said Yao. “One of the holy grails in physics is understanding what types of matter can exist in nature.” We have lots of strange materials like superconductors and superfluids, but “non equilibrium phases” like time crystals “represent a new avenue different from all the things we’ve studied in the past.”