Posted on by Nicholos Wethington

How Fast is the Speed of Light?

You may think that a lot of things are fast, like speeding bullets and Superman and the passage of time when you are having fun. But all of these things are nothing compared to the speed of light, which is the fastest that something can travel through the Universe. The speed of light is sometimes referred to as the “cosmic speed limit”. Light travels in a vacuum at 186,282.4 miles per second or 299,792,458 meters/second. For simplicity, it is often said that these numbers are 186,000 miles per second, and 3.00 x 10^8 meters per second.

How fast is this in normal terms? Well, the record for the fastest aircraft is held by the Boeing x-43 scramjet. Scramjets are single-use unmanned aircraft designed to go at hypersonic speeds. The x-43 traveled at  12,144 km/h (7,546 mph), or Mach 9.8, on November 16th, 2004. That is .000405% of the speed of light. And this is a jet that can travel from New York to Los Angeles in 20 minutes. While it takes photons about 8 minutes to travel the distance from the Sun to the Earth – at its furthest, 152 million km (94.4 million miles) – this scramjet traveling at its maximum speed would take about 522 days!

The speed of light is really fast, and at this speed some bizarre things start to happen. First off, photons can only travel this speed because they have zero rest mass, meaning that if you were to somehow trap a photon and put it on a scale, it would have no mass. It’s virtually impossible for something with mass to travel this speed, because as you get faster and faster, it takes more and more energy to get you to the speed of light, which makes you heavier, which requires more energy, etc. Time also changes when you get to these speeds. If you left the Earth going the speed of light, then came back around and landed, you would perceive time as moving normally, but when you returned it would seem as if time sped up for everybody on the Earth, and all of your friends and family would be much, much older.

The speed of light is not constant in all materials, though, and can be slowed down. Here’s an excellent article on how researchers can slow down the speed of light by passing it through different materials, with the slowest speed being 38 miles per hour!

To learn more about the speed of light – and there is a lot, lot more to learn, check out the Astronomy Cast questions shows from October 26, 2008,  June 4, 2009 and September 26, 2008, or the Physics section in the Guide to Space.

Sources:
Wikipedia
NASA

Posted on by Nancy Atkinson

Device Makes Radio Waves Travel Faster Than Light

Polarization Synchrotron. Credit: Singleton, et al., via Current.com

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A scientist has created a gadget that can make radio waves travel faster than light. Einstein predicted that particles and information can’t travel faster than the speed of light, but phenomena like radio waves are a different story, said John Singleton, who works at the Los Alamos National Laboratory. The polarization synchrotron combines the waves with a rapidly spinning magnetic field, and the result could explain why pulsars — which are super-dense spinning stars that are a subclass of neutron stars — emit such powerful signals, a phenomenon that has baffled many scientists.

Singleton said the polarization synchrotron basically abuses radio waves so severely that they finally give in and travel faster than light. This may be what happens in pulsars, as well.

“Pulsars are rapidly rotating neutron stars that emit radio waves in pulses, but what we don’t know is why these pulses are so bright or why they travel such long distances,” Singleton said. “What we think is these are transmitting the same way our machine does.”

The device consists of a 2 meter-long gently curving arc of alumina (a dielectric material), with a series of electrodes fitted at regular intervals along its length. Applying a sinusoidal voltage across each electrode and displacing the phase of the voltage very slightly from one electrode to the next generates a sinusoidally-varying polarization pattern that moves along the device. By carefully adjusting the frequency of the voltage and the phase displacement the researchers say they can make the wave travel at greater than the speed of light. However no physical quantity of charge travels faster than light speed.

And beyond explaining what has been a bit of a mystery to the astronomical community, Singleton’s discovery could have wide-ranging technological impacts in areas such as medicine and communications, he said.

“Because nobody’s really thought about things that travel faster than light before, this is a wide-open technological field,” Singleton said.

One possible use for faster than light radio waves — which are packed into a very powerful wave the size of a pencil point — could be the creation of a new generation of cell phones that communicate directly to satellites, rather than transmitting through relay towers as they now do.

Those phones would have more reliable service and would also be more difficult for hackers to intercept, Singleton said.

Speedy radio waves could also revolutionize the computing industry. Data could be transferred more quickly, and if used in semiconductors, it would mean faster caches and the ability to communicate across separate pieces of silicon nearly instantly.

In the health field, faster than light radio waves could be in extremely targeted chemotherapy, where a patient takes the drugs, and the radio waves are used to activate them very specifically in the area around a tumor, Singleton said.

Read the paper on the Polarization Synchrotron.

Sources: Current, Geek.com, Roland Piquepaille’s Technology Trends