Libro de Visitas

Brandonnig

11 Apr 2025 - 05:14 am

Space, time: The continual question
If time moves differently on the peaks of mountains than the shores of the ocean, you can imagine that things get even more bizarre the farther away from Earth you travel.
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To add more complication: Time also passes slower the faster a person or spacecraft is moving, according to Einstein’s theory of special relativity.

Astronauts on the International Space Station, for example, are lucky, said Dr. Bijunath Patla, a theoretical physicist with the US National Institute of Standards and Technology, in a phone interview. Though the space station orbits about 200 miles (322 kilometers) above Earth’s surface, it also travels at high speeds — looping the planet 16 times per day — so the effects of relativity somewhat cancel each other out, Patla said. For that reason, astronauts on the orbiting laboratory can easily use Earth time to stay on schedule.
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For other missions — it’s not so simple.

Fortunately, scientists already have decades of experience contending with the complexities.

Spacecraft, for example, are equipped with their own clocks called oscillators, Gramling said.

“They maintain their own time,” Gramling said. “And most of our operations for spacecraft — even spacecraft that are all the way out at Pluto, or the Kuiper Belt, like New Horizons — (rely on) ground stations that are back on Earth. So everything they’re doing has to correlate with UTC.”
But those spacecraft also rely on their own kept time, Gramling said. Vehicles exploring deep into the solar system, for example, have to know — based on their own time scale — when they are approaching a planet in case the spacecraft needs to use that planetary body for navigational purposes, she added.

For 50 years, scientists have also been able to observe atomic clocks that are tucked aboard GPS satellites, which orbit Earth about 12,550 miles (20,200 kilometers) away — or about one-nineteenth the distance between our planet and the moon.

Studying those clocks has given scientists a great starting point to begin extrapolating further as they set out to establish a new time scale for the moon, Patla said.

“We can easily compare (GPS) clocks to clocks on the ground,” Patla said, adding that scientists have found a way to gently slow GPS clocks down, making them tick more in-line with Earth-bound clocks. “Obviously, it’s not as easy as it sounds, but it’s easier than making a mess.”

Frankjuita

11 Apr 2025 - 04:25 am

Lunar clockwork
What scientists know for certain is that they need to get precision timekeeping instruments to the moon.
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Exactly who pays for lunar clocks, which type of clocks will go, and where they’ll be positioned are all questions that remain up in the air, Gramling said.

“We have to work all of this out,” she said. “I don’t think we know yet. I think it will be an amalgamation of several different things.”
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Atomic clocks, Gramling noted, are great for long-term stability, and crystal oscillators have an advantage for short-term stability.
“You never trust one clock,” Gramling added. “And you never trust two clocks.”

Clocks of various types could be placed inside satellites that orbit the moon or perhaps at the precise locations on the lunar surface that astronauts will one day visit.

As for price, an atomic clock worthy of space travel could cost around a few million dollars, according Gramling, with crystal oscillators coming in substantially cheaper.

But, Patla said, you get what you pay for.

“The very cheap oscillators may be off by milliseconds or even 10s of milliseconds,” he added. “And that is important because for navigation purposes — we need to have the clocks synchronized to 10s of nanoseconds.”

A network of clocks on the moon could work in concert to inform the new lunar time scale, just as atomic clocks do for UTC on Earth.

(There will not, Gramling added, be different time zones on the moon. “There have been conversations about creating different zones, with the answer: ‘No,’” she said. “But that could change in the future.”)

Peterrig

11 Apr 2025 - 03:40 am

‘A whole different mindset’
Accurate clockwork is one matter. But how future astronauts living and working on the lunar surface will experience time is a different question entirely.
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On Earth, our sense of one day is governed by the fact that the planet completes one rotation every 24 hours, giving most locations a consistent cycle of daylight and darkened nights. On the moon, however, the equator receives roughly 14 days of sunlight followed by 14 days of darkness.

“It’s just a very, very different concept” on the moon, Betts said. “And (NASA is) talking about landing astronauts in the very interesting south polar region (of the moon), where you have permanently lit and permanently shadowed areas. So, that’s a whole other set of confusion.”
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“It’ll be challenging” for those astronauts, Betts added. “It’s so different than Earth, and it’s just a whole different mindset.”

That will be true no matter what time is displayed on the astronauts’ watches.

Still, precision timekeeping matters — not just for the sake of scientifically understanding the passage of time on the moon but also for setting up all the infrastructure necessary to carry out missions.

The beauty of creating a time scale from scratch, Gramling said, is that scientists can take everything they have learned about timekeeping on Earth and apply it to a new system on the moon.

And if scientists can get it right on the moon, she added, they can get it right later down the road if NASA fulfills its goal of sending astronauts deeper into the solar system.

“We are very much looking at executing this on the moon, learning what we can learn,” Gramling said, “so that we are prepared to do the same thing on Mars or other future bodies.”

Jeffreytwera

11 Apr 2025 - 03:34 am

Lunar clockwork
What scientists know for certain is that they need to get precision timekeeping instruments to the moon.
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Exactly who pays for lunar clocks, which type of clocks will go, and where they’ll be positioned are all questions that remain up in the air, Gramling said.

“We have to work all of this out,” she said. “I don’t think we know yet. I think it will be an amalgamation of several different things.”
https://kra30c.cc
kra31cc
Atomic clocks, Gramling noted, are great for long-term stability, and crystal oscillators have an advantage for short-term stability.
“You never trust one clock,” Gramling added. “And you never trust two clocks.”

Clocks of various types could be placed inside satellites that orbit the moon or perhaps at the precise locations on the lunar surface that astronauts will one day visit.

As for price, an atomic clock worthy of space travel could cost around a few million dollars, according Gramling, with crystal oscillators coming in substantially cheaper.

But, Patla said, you get what you pay for.

“The very cheap oscillators may be off by milliseconds or even 10s of milliseconds,” he added. “And that is important because for navigation purposes — we need to have the clocks synchronized to 10s of nanoseconds.”

A network of clocks on the moon could work in concert to inform the new lunar time scale, just as atomic clocks do for UTC on Earth.

(There will not, Gramling added, be different time zones on the moon. “There have been conversations about creating different zones, with the answer: ‘No,’” she said. “But that could change in the future.”)

Michaelew

11 Apr 2025 - 01:48 am

Мені завжди було цікаво, чому ефект гравітації в космосі. Нарешті знайшов відповідь тут: сила тяжіння.

Danielres

10 Apr 2025 - 11:17 pm

‘White Lotus’ villain Jon Gries reveals the true crimes that inspired his twisty take on Greg/Gary
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When Season 3 of “The White Lotus” premiered last month, the shock was palpable when returning character Belinda recognized a familiar face at the resort in Thailand: Greg Hunt, the wily suitor of the late Tanya McQuoid.

As the season has unfolded, Greg (played by Jon Gries) has emerged as an antagonist, particularly after Belinda dove into the investigation surrounding Tanya’s death and learned that Greg, who now goes by Gary, evaded questioning by authorities.

On a show famous for reinventing itself, the same has been asked of the actor, who says that playing the ever-shifting character has been a welcome challenge and, like “White Lotus” itself, full of twists.

“In the beginning, I totally played him for a guy who was, you know, on his last legs,” Gries said in a recent interview with CNN, referencing Greg’s very apparent ill health in the first season of “White Lotus,” which premiered to rave reviews in summer 2021. He added: “When you play a character, you want to find his empathetic side, and you want to understand where they came from, and what got them to where they are.”

But when he was contacted by creator Mike White about appearing in Season 2, Gries realized he would have to adjust his framing of Greg, despite having previously imagined a “comprehensive history” for him on his own.

“(White) said, ‘I’m writing it right now, and I’m writing you, and I just need to know here and now: If you’re in, I’ll continue writing. If not, I’ll stop,’” Gries recalled.

Herbertrit

10 Apr 2025 - 04:23 pm

A tiny rainforest country is growing into a petrostate. A US oil company could reap the biggest rewards
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Guyana’s destiny changed in 2015. US fossil fuel giant Exxon discovered nearly 11 billion barrels of oil in the deep water off the coast of this tiny, rainforested country.

It was one of the most spectacular oil discoveries of recent decades. By 2019, Exxon and its partners, US oil company Hess and China-headquartered CNOOC, had started producing the fossil fuel.? They now pump around 650,000 barrels of oil a day, with plans to more than double this to 1.3 million by 2027.

Guyana now has the world’s highest expected oil production growth through 2035.

This country — sandwiched between Brazil, Venezuela and Suriname — has been hailed as a climate champion for the lush, well-preserved forests that carpet nearly 90% of its land. It is on the path to becoming a petrostate at the same time as the impacts of the fossil fuel-driven climate crisis escalate.

While the government says environmental protection and an oil industry can go hand-in-hand, and low-income countries must be allowed to exploit their own resources, critics say it’s a dangerous path in a warming world, and the benefits may ultimately skew toward Exxon — not Guyana.

Billygaica

10 Apr 2025 - 04:07 pm

Mist and microlightning
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To recreate a scenario that may have produced Earth’s first organic molecules, researchers built upon experiments from 1953 when American chemists Stanley Miller and Harold Urey concocted a gas mixture mimicking the atmosphere of ancient Earth. Miller and Urey combined ammonia (NH3), methane (CH4), hydrogen (H2) and water, enclosed their “atmosphere” inside a glass sphere and jolted it with electricity, producing simple amino acids containing carbon and nitrogen. The Miller-Urey experiment, as it is now known, supported the scientific theory of abiogenesis: that life could emerge from nonliving molecules.
For the new study, scientists revisited the 1953 experiments but directed their attention toward electrical activity on a smaller scale, said senior study author Dr. Richard Zare, the Marguerite Blake Wilbur Professor of Natural Science and professor of chemistry at Stanford University in California. Zare and his colleagues looked at electricity exchange between charged water droplets measuring between 1 micron and 20 microns in diameter. (The width of a human hair is 100 microns.)

“The big droplets are positively charged. The little droplets are negatively charged,” Zare told CNN. “When droplets that have opposite charges are close together, electrons can jump from the negatively charged droplet to the positively charged droplet.”
The researchers mixed ammonia, carbon dioxide, methane and nitrogen in a glass bulb, then sprayed the gases with water mist, using a high-speed camera to capture faint flashes of microlightning in the vapor. When they examined the bulb’s contents, they found organic molecules with carbon-nitrogen bonds. These included the amino acid glycine and uracil, a nucleotide base in RNA.

“We discovered no new chemistry; we have actually reproduced all the chemistry that Miller and Urey did in 1953,” Zare said. Nor did the team discover new physics, he added — the experiments were based on known principles of electrostatics.

“What we have done, for the first time, is we have seen that little droplets, when they’re formed from water, actually emit light and get this spark,” Zare said. “That’s new. And that spark causes all types of chemical transformations.”

Anthonycaphy

10 Apr 2025 - 03:08 pm

Scientists redid an experiment that showed how life on Earth could have started. They found a new possibility
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In the 1931 movie “Frankenstein,” Dr. Henry Frankenstein howling his triumph was an electrifying moment in more ways than one. As massive bolts of lightning and energy crackled, Frankenstein’s monster stirred on a laboratory table, its corpse brought to life by the power of electricity.

Electrical energy may also have sparked the beginnings of life on Earth billions of years ago, though with a bit less scenery-chewing than that classic film scene.

Earth is around 4.5 billion years old, and the oldest direct fossil evidence of ancient life — stromatolites, or microscopic organisms preserved in layers known as microbial mats — is about 3.5 billion years old. However, some scientists suspect life originated even earlier, emerging from accumulated organic molecules in primitive bodies of water, a mixture sometimes referred to as primordial soup.

But where did that organic material come from in the first place? Researchers decades ago proposed that lightning caused chemical reactions in ancient Earth’s oceans and spontaneously produced the organic molecules.

Now, new research published March 14 in the journal Science Advances suggests that fizzes of barely visible “microlightning,” generated between charged droplets of water mist, could have been potent enough to cook up amino acids from inorganic material. Amino acids — organic molecules that combine to form proteins — are life’s most basic building blocks and would have been the first step toward the evolution of life.

Carlostibra

10 Apr 2025 - 03:07 pm

Mindful wellness challenges
If you’re the type of person who thrives on challenges and pushing your limits, this doesn’t mean you need to shy away from wellness challenges altogether. But before diving in, take a step back and ask yourself if you’re pursuing the challenge for the right reasons, McGregor said.
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Some people want to try these challenges because they believe something is missing from their life, and they’re looking to attain “worth” or receive validation, McGregor noted.

A good way to assess your motivation is by considering whether the challenge will benefit your health or if it’s about showcasing your accomplishments on social media or some other reason.

Before trying any new trend, make sure you have the foundation to handle it and be aware of any potential risks, McGregor said.

For casual runners, this might mean signing up for a 5K but building your endurance gradually while incorporating other strength training exercises into your routine. For more intense challenges, such as a marathon, McGregor encourages people to consult with professionals or a coach who can monitor your progress and condition along the way.

Focusing on sustainable habits
Both McGregor and Curran emphasize the importance of fostering sustainable health habits before embarking on more extreme challenges.

Rather than chasing the idea of being “healthy,” McGregor suggests focusing on actual healthful behaviors and starting small.

If you’re a highly sedentary person and want to add more movement to your day, try doing lunges while brushing your teeth or taking short walks throughout your typical routine.