Science!! Fucking magnets, how do they work?

The physicists were exploring the properties of photons ? an elementary particle that is the most basic constituent of light and all other types of electromagnetic radiation ? when they managed to create molecules formed from photons bound together.

The discovery is startling as it goes against what scientists have previously believed to be the signature quality of photons: that they are massless particles that do not interact with each other. The capacity to create molecules out of photons has been described by the physicists involved as ?pushing the frontiers of science?.

To get the photons to interact with one another the team from the Harvard-MIT Center for Ultracold Atoms (a group led by Lukin alongside MIT Professor of Physics Vladan Vuletic) cooled rubidium atoms in a vacuum chamber to just a few degrees above absolute zero ? the coldest possible temperature at which particles do not move.

When two photons were fired at the cloud they did not pass through it and exit individually (as had been expected) but emerged on the other side as a single molecule. This was due to the Rydberg blockade, which states that when an atom is excited (has energy imparted to it) nearby atoms cannot be excited to the same degree.

This meant that as the first photon excited atoms in the cloud but had to move on before the second photon could do the same. Lukin describes the end result as the photons pushing and pulling each other through the cloud.

"It's a photonic interaction that's mediated by the atomic interaction," said Lukin. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."

Tuco · Sep 26, 2013

"We got a couple of photons to interact with each other"

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iannis · Sep 26, 2013

Not that I know shit about fuck, but the way it's written it kinda sounds like an atomic lens. Two photons go in, two photons come out. Can't explain that.

It's shit like this that makes me doubt cosmology on a fundamental level. Not because cosmologists are dishonest or less than diligent, not because the foundational science is bunk, not because of any negative attribute that could be ascribed to the methods, researchers, or thinkers themselves, but because there are probably effects and phenomena which we are not even aware of which inform our quantified interpretation of the observable universe. And the way to find those effects and phenomena are through continued study.

As science it's great. As philosophy it's sub-par.

Big Phoenix · Sep 26, 2013

Luminati_sl said:
Tuco, can you please get cancer and die irl?

Bro you where a good guy in EQ why you so hostile irl?

fanaskin · Sep 27, 2013

Giant hornets are science right?...

Hornet attacks kill dozens in China

fucker_sl · Sep 29, 2013

so...i just stumbled on some youtube ppl who are claiming that general relativity is a scam and that GPS system has proved that the time dilation effect doesnt exist

im 99.999999% sure they are just retards but ill ask anyway....anyone here works on GPS technology and can confirm/deny that GPS doesnt consider the time dilation effect on its signals?

Big Phoenix · Sep 29, 2013

Uh GPS is quite possibly the biggest example of time dilation. They use them special atomic clocks to make sure they stay sync'd up.

Error analysis for the Global Positioning System - Wikipedia, the free encyclopedia

According to the theory of relativity, due to their constant movement and height relative to the Earth-centered, non-rotating approximately inertial reference frame, the clocks on the satellites are affected by their speed. Special relativity predicts that the frequency of the atomic clocks moving at GPS orbital speeds will tick more slowly than stationary ground clocks by a factor of \frac{v^{2}}{2c^{2}}\approx 10 ^{-10}, or result in a delay of about 7 ?s/day, where the orbital velocity is v = 4 km/s, and c = the speed of light. The time dilation effect has been measured and verified using the GPS.

The effect of gravitational frequency shift on the GPS due to general relativity is that a clock closer to a massive object will be slower than a clock farther away. Applied to the GPS, the receivers are much closer to Earth than the satellites, causing the GPS clocks to be faster by a factor of 5?10^(?10), or about 45.9 ?s/day. This gravitational frequency shift is noticeable.

When combining the time dilation and gravitational frequency shift, the discrepancy is about 38 microseconds per day, a difference of 4.465 parts in 1010.[11] Without correction, errors in the initial pseudorange of roughly 10 km/day would accumulate. This initial pseudorange error is corrected in the process of solving the navigation equations. In addition the elliptical, rather than perfectly circular, satellite orbits cause the time dilation and gravitational frequency shift effects to vary with time. This eccentricity effect causes the clock rate difference between a GPS satellite and a receiver to increase or decrease depending on the altitude of the satellite.

To compensate for the discrepancy, the frequency standard on board each satellite is given a rate offset prior to launch, making it run slightly slower than the desired frequency on Earth; specifically, at 10.22999999543 MHz instead of 10.23 MHz.[12] Since the atomic clocks on board the GPS satellites are precisely tuned, it makes the system a practical engineering application of the scientific theory of relativity in a real-world environment.[13] Placing atomic clocks on artificial satellites to test Einstein's general theory was proposed by Friedwardt Winterberg in 1955.[14]
Calculation of time dilation

Atomic clock - Wikipedia, the free encyclopedia

A GPS receiver works by measuring the relative time delay of signals from a minimum of four, but usually more GPS satellites, each of which has four onboard caesium or rubidium atomic clocks.

Jysin · Sep 29, 2013

There was a pretty cool "Into the Universe" episode where they went specifically into this. Time dilation as in: closer to mass, the more time is (relatively) slowed down to time measured further away. Scientists in Greenwich took two identical clocks extremely sync'd to who knows how many fractions of seconds. They actually proved time dilation simply by placing one clock elevated 10ft or so above the other. The lower clock (nearest to mass = Earth) was slower than the one above it.

I am sure Google could explain the details better, but I'm lazy.

Araxen · Sep 29, 2013

Furry · Sep 30, 2013

Jysin_sl said:
There was a pretty cool "Into the Universe" episode where they went specifically into this. Time dilation as in: closer to mass, the more time is (relatively) slowed down to time measured further away. Scientists in Greenwich took two identical clocks extremely sync'd to who knows how many fractions of seconds. They actually proved time dilation simply by placing one clock elevated 10ft or so above the other. The lower clock (nearest to mass = Earth) was slower than the one above it.

I am sure Google could explain the details better, but I'm lazy.

I assume your talking about pound rebka?

They used clocks in some sense of the word, but to better understand that experiment and its implications and problems, you have to understand exactly what a clock is. The pound rebka experiment proves that atomic interactions occur with less energy closer to mass. This simple fact is why clocks run faster the further they are from a source of mass, and why clocks on satellites have to run at a different speed on earth to be accurate while in space. GPS considers this fact in its calculations. Relativity also made the prediction that moving clocks are slowed/sped up relatively. GPS makes no calculations for that. Additionally, GPS satellite clocks have to be corrected frequently. They often get off because our math on where they are and what their time should be frequently is incorrect.

Essentially, clocks cant prove relativity, but there isn't enough evidence to say they disprove it either. They aren't designed with that task in mind.

Furry · Sep 30, 2013

1 click two posts

Jysin · Sep 30, 2013

Furry_sl said:
I assume your talking about pound rebka?

They used clocks in some sense of the word, but to better understand that experiment and its implications and problems, you have to understand exactly what a clock is. The pound rebka experiment proves that atomic interactions occur with less energy closer to mass. This simple fact is why clocks run faster the further they are from a source of mass, and why clocks on satellites have to run at a different speed on earth to be accurate while in space. GPS considers this fact in its calculations. Relativity also made the prediction that moving clocks are slowed/sped up relatively. GPS makes no calculations for that. Additionally, GPS satellite clocks have to be corrected frequently. They often get off because our math on where they are and what their time should be frequently is incorrect.

Essentially, clocks cant prove relativity, but there isn't enough evidence to say they disprove it either. They aren't designed with that task in mind.

Pound Rebka was a test involving observations with the Viking 1.

I was talking about:
Optical Clocks and Relativity

Thanks to improved timekeeping, similar demonstrations can now take place at more mundane scales in the laboratory. In a series of experiments described in the September 24 issue of Science, researchers at the National Institute of Standards and Technology (NIST) in Boulder, Colo., registered differences in the passage of time between two high-precision optical atomic clocks whenone was elevated by just a third of a meteror when one was set in motion at speeds of less than 10 meters per second.

I think we are in agreement here though, but Time Dialation is achieved both ways.

1) Gravitational Time Dilation = in respect to distance to mass
2) Relative Velocity Time Dilation = in respect to velocity(ies) traveled.
3) Combination of both

Wiki_sl said:
In the theory of relativity, time dilation is an actual difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses.

An accurate clock at rest with respect to one observer may be measured to tick at a different rate when compared to a second observer's own equally accurate clocks. This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself.

Time dilation - Wikipedia, the free encyclopedia

tad10 · Sep 30, 2013

Tuco_sl said:
"We got a couple of photons to interact with each other"

NEW MATTER DISCOVERED LIGHTSABRES CONFIRMED

I don't know about lightsabers (which are supposedly confined plasma not lasers, IIRC my pseudo-SW science) but 3D displays "in space" seem possible.

Science!! Fucking magnets, how do they work?

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