CWL

davidreese:

Artist/programmer/designer Marcin Ignac used software to track, measure, and visualize his computer use every day for 2.5 years. The result: This beautiful, simple look at one of the most prominent aspects of daily life in the 21st century. Each line is a single day, with colors representing which app was being used at the time of day. (So, for example, your line might be red during this time, signaling that you’re using your browser.) The black sections are times when he had his computer off—meaning that blacked-out section in every day is probably night.

wildlydistorted:

Time - Bill Nye the Science Guy
What exactly is time? A fun and simple explanation of time and Einstein’s theory of General Relativity.
There’s also some incredibly badass clips of Einstein speaking that I would love to make gifs out of.

Eternal Clock Could Keep Time After Universe Dies

The idea for an eternal clock that would continue to keep time even after the universe ceased to exist has intrigued physicists. However, no one has figured out how one might be built, until now.

Researchers have now proposed an experimental design for a “space-time crystal” that would be able to keep time forever. This four-dimensional crystal would be similar to conventional 3D crystals, which are structures, like snowflakes and diamonds, whose atoms are arranged in repeating patterns. Whereas a diamond has a periodic structure in three dimensions, the space-time crystal would be periodic in time as well as space.

The idea of a 4D space-time crystal was first proposed earlier this year by MIT physicist Frank Wilczek, though the concept was purely theoretical. Now a team of researchers led by Xiang Zhang of California’s Lawrence Berkeley National Laboratory has conceived of how to make one a reality.

“The idea of creating a crystal with dimensions higher than that of conventional 3D crystals is an important conceptual breakthrough in physics, and it is very exciting for us to be the first to devise a way to realize a space-time crystal,” Berkeley Lab physicist Tongcang Li, a member of the research group, said in a statement.

Zhang and his colleagues suggest that a space-time crystal could be constructed using an electric field to trap charged atoms (called ions), and taking advantage of the natural repulsion between two like-charged particles (positive and positive, or negative and negative), which is called Coulomb repulsion.

Image: This proposed space-time crystal shows (a) periodic structures in both space and time with (b) ultracold ions rotating in one direction even at the lowest energy state. Credit: Courtesy of Xiang Zhang group

Full Article

sciencecenter:

Sticklers for punctuality, prepare yourself for the upcoming leap second

Surely everyone has heard of the leap year, in which every fourth year is extended by a day to compensate for Earth’s slightly irregular orbit around the sun. But you probably haven’t heard of the leap second. Mark Brown of Wired UK has the scoop:

The International Earth Rotation and Reference Systems Service (IERS) in Paris — the grand arbiters of time on our big blue marble — has declared that a leap second will be introduced on 30 June, 2012. […]

We used to use the Earth’s dutiful rotation as a way of measuring time. It pirouettes on its axis once every 24 hours, which can then be divided into minutes and seconds. But the Earth’s rotation is annoyingly irregular, with some days ending up being a tiny bit longer or shorter than others.

There’s nothing science hates more than unpredictability, so in the 1950s atomic clocks were introduced to keep time.

By measuring the regular atomic vibration in the element cesium (which oscillates exactly 9,192,631,770 times a second), we ended up with a clock that can be used to score off seconds with remarkable accuracy. Multiple atomic clocks work in unison to precisely calculate world time.

But that leaves a problem. If we lived on atomic time it’d very slowly gravitate away from the Earth’s actual time. In a few years we’d be a second out of sync, in hundreds of years we’d be a minute out and after several hundred thousand years we could be eating lunch in the middle of the night.

So time-keepers introduced the leap second. As the atomic clock’s perfect accuracy (known as International Atomic Time, or TAI, from the French name Temps Atomique International) veers farther and farther away from the Earth’s clumsy rotation (called Solar Time), the IERS introduces a leap second to bring them back into perfect parity (known as Coordinated Universal Time, or UTC).

Click here to read the rest.

About Time: Everyday Time Warps

Despite Einstein’s theory of relativity proving otherwise, society still for the most part believes time is as simple as a storybook with a neat linear storyline. Don’t let your evolving human senses fool you. Here are some points to help you reconsider that thought.

Space Age

Russian astronaut Sergei Krikalev has spent longer in space than anyone else - 803 days in total. While space’s weaker gravity aged him, this was outweighed by the rejuvenating effect of his high speed. So he is 21 milliseconds younger than if he had stayed put.

Round-The-World Flights

Repeat a famous experiment carried out with atomic clocks and you will age 40 nanoseconds less if you circle the globe eastward, in the direction of Earth’s rotation. Fly west, though, and you will age 273 nanoseconds extra (Science, vol 177, p 166).

Your Head Ages More Than Your Feet

…by around 10-11 seconds a day. Live for 80 years and that difference adds up to 300 nanoseconds.

Location, Location, Location

A year atop Australia’s tallest apartment block will make you 950 nanoseconds older than a bungalow-dweller.

The Youthful Dead Sea

Spend 40 years by the shores of the Dead Sea, at the lowest elevations on the Earth’s surface, and you’ll age 48 microseconds less than someone living at sea level, and 750 microseconds less than the residents of La Rinconada in Peru, at an altitude of 5100.metres.

Had time truly been a constant, a linear variable of the universe it would apply itself equally and sequentially throughout our lives. But as we look closer, it clearly looks like that is far from the reality of things.

“The truly odd thing is that the laws of physics, which surely ought to be responsible for what we see in the world, can work just as well both forwards and backwards in time,” says Dean Rickles, a philosopher of science at the University of Sydney in New South Wales, Australia. “There shouldn’t be an arrow.”

If time’s arrow is not in the laws of physics, where does it come from? An important clue emerges from the complex interactions of large numbers of particles. Every object you see around you, including you, is made up of a vast collection of particles. These particles are not just sitting around - they are constantly shuffling about and rearranging.

Image via SNES 16-Bit Doctor Who Intro (2010)

The Fabric of The Cosmos: The Illusion of Time

Host and theoretical physicist Brian Greene brings us the second iteration to ‘The Fabric of The Cosmos’.

Time. We waste it, save it, kill it, make it. The world runs on it. Yet ask physicists what time actually is, and the answer might shock you: They have no idea. Even more surprising, the deep sense we have of time passing from present to past may be nothing more than an illusion. How can our understanding of something so familiar be so wrong? In search of answers, Brian Greene takes us on the ultimate time-traveling adventure, hurtling 50 years into the future before stepping into a wormhole to travel back to the past.

Along the way, he will reveal a new way of thinking about time in which moments past, present, and future—from the reign of T. rex to the birth of your great-great-grandchildren—exist all at once. This journey will bring us all the way back to the Big Bang, where physicists think the ultimate secrets of time may be hidden. You’ll never look at your wristwatch the same way again.

Since the last 6 minutes of this video was mistakenly cut-off, here’s the rest.

SNES 16-Bit Doctor Who Intro (2010)

A Super Nintendo style recreation of the “Doctor Who” intro sequence.

About Time: Everyday Time Warps

Despite Einstein’s theory of relativity proving otherwise, society still for the most part believes time is as simple as a storybook with a neat linear storyline. Don’t let your evolving human senses fool you. Here are some points to help you reconsider that thought.

Space Age

Russian astronaut Sergei Krikalev has spent longer in space than anyone else - 803 days in total. While space’s weaker gravity aged him, this was outweighed by the rejuvenating effect of his high speed. So he is 21 milliseconds younger than if he had stayed put.

Round-The-World Flights

Repeat a famous experiment carried out with atomic clocks and you will age 40 nanoseconds less if you circle the globe eastward, in the direction of Earth’s rotation. Fly west, though, and you will age 273 nanoseconds extra (Science, vol 177, p 166).

Your Head Ages More Than Your Feet

…by around 10-11 seconds a day. Live for 80 years and that difference adds up to 300 nanoseconds.

Location, Location, Location

A year atop Australia’s tallest apartment block will make you 950 nanoseconds older than a bungalow-dweller.

The Youthful Dead Sea

Spend 40 years by the shores of the Dead Sea, at the lowest elevations on the Earth’s surface, and you’ll age 48 microseconds less than someone living at sea level, and 750 microseconds less than the residents of La Rinconada in Peru, at an altitude of 5100.metres.

Had time truly been a constant, a linear variable of the universe it would apply itself equally and sequentially throughout our lives. But as we look closer, it clearly looks like that is far from the reality of things.

“The truly odd thing is that the laws of physics, which surely ought to be responsible for what we see in the world, can work just as well both forwards and backwards in time,” says Dean Rickles, a philosopher of science at the University of Sydney in New South Wales, Australia. “There shouldn’t be an arrow.”

If time’s arrow is not in the laws of physics, where does it come from? An important clue emerges from the complex interactions of large numbers of particles. Every object you see around you, including you, is made up of a vast collection of particles. These particles are not just sitting around - they are constantly shuffling about and rearranging.

Image via SNES 16-Bit Doctor Who Intro (2010)

Time Dilation

One of the most enthralling aspects of Relativity is its new understanding of time. The term “time dilation” might evoke images of Salvadore Dali’s timepieces hanging on twigs, however, time dilation is all but surrealistic. As stated earlier, if the speed of light is constant, time cannot be constant. In fact, it doesn’t make sense to speak of time as being constant or absolute, when we think of it as one dimension of spacetime. Special Relativity states that time is measured according to the relative velocity of the reference frame it is measured in. Despite of the simplicity of this statement, the relativistic connection between time and space are hard to fathom. There are numerous ways to illustrate this:

The four dimensions of spacetime.

In Relativity the world has four dimensions: three space dimensions and one dimension that is not exactly time but related to time. In fact, it is time multiplied by the square root of -1. Say, you move through one space dimension from point A to point B. When you move to another space coordinate, you automatically cause your position on the time coordinate to change, even if you don’t notice. This causes time to elapse. Of course, you are always travelling through time, but when you travel through space you travel through time by less than you expect. Consider the following example:

Time dilation; the twin paradox.

There are two twin brothers. On their thirtieth birthday, one of the brothers goes on a space journey in a superfast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.

What happens if an astronaut falls into a black hole?

The gravitational time dilation effect a black hole produces is equal to that of an object moving near the speed of light. For example, an observer far from a black hole would observe time passing extremely slowly for an astronaut falling through the hole’s boundary. In fact, the distant observer would never see the hapless victim actually fall in. His or her time, as measured by the observer, would appear to stand still.

From the perspective of the unlucky astronaut, things would, of course, look quite different. After having passed the black hole’s event horizon, the point in space from which nothing can escape its pull, there is no way back. While approaching the centre, the gravitational pull on the astronaut’s head and feet differs so strongly that the body would be stretched out “like spaghetti” (Stephen Hawking). Hence, it may be a good idea to stay away from black holes, should they actually exist.

Via Spacetime-TimeDilation

The Time Traveler Cosmonaut

The greatest time traveler to date is Sergei Krikalev, a cosmonaut who spent more than 803 days in low-Earth orbit, traveling at high speed, and thus has aged 1/48th of a second less than he would have if he had stayed home. When he returned to Earth, he found the Earth to be 1/48th of a second to the future of where he expected it to be. So he has time-traveled 1/48th of a second into the future. If you were to fly out to the star Betelgeuse, 500 light-years away, at 99.995 percent of the speed of light and then return at the same speed, the Earth would be 1,000 years older when you got back, but you would only have aged 10 years.

Credit: Heather Wax

Time Dilation

One of the most enthralling aspects of Relativity is its new understanding of time. The term “time dilation” might evoke images of Salvadore Dali’s timepieces hanging on twigs, however, time dilation is all but surrealistic. As stated earlier, if the speed of light is constant, time cannot be constant. In fact, it doesn’t make sense to speak of time as being constant or absolute, when we think of it as one dimension of spacetime. Special Relativity states that time is measured according to the relative velocity of the reference frame it is measured in. Despite of the simplicity of this statement, the relativistic connection between time and space are hard to fathom. There are numerous ways to illustrate this:

The four dimensions of spacetime.

In Relativity the world has four dimensions: three space dimensions and one dimension that is not exactly time but related to time. In fact, it is time multiplied by the square root of -1. Say, you move through one space dimension from point A to point B. When you move to another space coordinate, you automatically cause your position on the time coordinate to change, even if you don’t notice. This causes time to elapse. Of course, you are always travelling through time, but when you travel through space you travel through time by less than you expect. Consider the following example:

Time dilation; the twin paradox.

There are two twin brothers. On their thirtieth birthday, one of the brothers goes on a space journey in a superfast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.

What happens if an astronaut falls into a black hole?

The gravitational time dilation effect a black hole produces is equal to that of an object moving near the speed of light. For example, an observer far from a black hole would observe time passing extremely slowly for an astronaut falling through the hole’s boundary. In fact, the distant observer would never see the hapless victim actually fall in. His or her time, as measured by the observer, would appear to stand still.

From the perspective of the unlucky astronaut, things would, of course, look quite different. After having passed the black hole’s event horizon, the point in space from which nothing can escape its pull, there is no way back. While approaching the centre, the gravitational pull on the astronaut’s head and feet differs so strongly that the body would be stretched out “like spaghetti” (Stephen Hawking). Hence, it may be a good idea to stay away from black holes, should they actually exist.

Via Spacetime-TimeDilation

Time Dilation

One of the most enthralling aspects of Relativity is its new understanding of time. The term “time dilation” might evoke images of Salvadore Dali’s timepieces hanging on twigs, however, time dilation is all but surrealistic. As stated earlier, if the speed of light is constant, time cannot be constant. In fact, it doesn’t make sense to speak of time as being constant or absolute, when we think of it as one dimension of spacetime. Special Relativity states that time is measured according to the relative velocity of the reference frame it is measured in. Despite of the simplicity of this statement, the relativistic connection between time and space are hard to fathom. There are numerous ways to illustrate this:

The four dimensions of spacetime.

In Relativity the world has four dimensions: three space dimensions and one dimension that is not exactly time but related to time. In fact, it is time multiplied by the square root of -1. Say, you move through one space dimension from point A to point B. When you move to another space coordinate, you automatically cause your position on the time coordinate to change, even if you don’t notice. This causes time to elapse. Of course, you are always travelling through time, but when you travel through space you travel through time by less than you expect. Consider the following example:

Time dilation; the twin paradox.

There are two twin brothers. On their thirtieth birthday, one of the brothers goes on a space journey in a superfast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.

What happens if an astronaut falls into a black hole?

The gravitational time dilation effect a black hole produces is equal to that of an object moving near the speed of light. For example, an observer far from a black hole would observe time passing extremely slowly for an astronaut falling through the hole’s boundary. In fact, the distant observer would never see the hapless victim actually fall in. His or her time, as measured by the observer, would appear to stand still.

From the perspective of the unlucky astronaut, things would, of course, look quite different. After having passed the black hole’s event horizon, the point in space from which nothing can escape its pull, there is no way back. While approaching the centre, the gravitational pull on the astronaut’s head and feet differs so strongly that the body would be stretched out “like spaghetti” (Stephen Hawking). Hence, it may be a good idea to stay away from black holes, should they actually exist.

Via Spacetime-TimeDilation