Physics: At the Heart of Everything

I'm Amber and I'm from Ireland. This is a blog mostly about physics but with some other interesting things thrown in. So if you have an interest (as I do) in astrophysics, particle physics, theoretical physics, mathematics, technology and other science related topics, then I invite you to follow my blog.

A tongue of lava oozes out from beneath the recently cooled crust of a flow. The silica contained within, reflects the early morning sunlight, giving its surface a glassy sheen.

Photo and caption credit: Bruce Omori

Pics I’ve taken at the observatory. A 4 second exposure on a 14” reflector (yeah we have a really old TV). Click pics for descriptions if you please

Electric discharge showing the lightning-like plasma filaments from a Tesla coil.

GIF from photos courtesy of Dan McCauley

Kirlian photography

Kirlian photography is a collection of photographic techniques used to capture the phenomenon of electrical coronal discharges. It is named after Semyon Kirlian, who, in 1939 accidentally discovered that if an object on a photographic plate is connected to a high-voltage source, an image is produced on the photographic plate.

Kirlian photography is a technique for creating contact print photographs using high voltage. The process entails placing sheet photographic film on top of a metal discharge plate. The object to be photographed is then placed directly on top of the film. High voltage is momentarily applied to the metal plate, thus creating an exposure. The corona discharge between the object and the high voltage plate is captured by the film. The developed film results in a Kirlian photograph of the object.

Color photographic film is calibrated to faithfully produce colors when exposed to normal light. Corona discharges can interact with minute variations in the different layers of dye used in the film, resulting in a wide variety of colors depending on the local intensity of the discharge. Film and digital imaging techniques also record light produced by photons emitted during corona discharge (see Mechanism of corona discharge).

Photographs of inanimate objects such as a coins, keys and leaves can be made more effectively by grounding the object to the earth, a cold water pipe or to the opposite (polarity) side of the high voltage source. Grounding the object creates a stronger corona discharge.

Kirlian photography does not require the use of a camera or a lens because it is a contact print process. It is possible to use a transparent electrode in place of the high voltage discharge plate, allowing one to capture the resulting corona discharge with a standard camera or a video camera.

The problem of space junk or space debris is increasing. And with out greater dependence on satellites is a grave problem.

There’s a lot of debris floating around in space, and researchers at the Lawrence Livermore National Lab are using supercomputers, optical sensors and other technology to track even small objects that could damage important satellites.

John Henderson, a space scientist at LLNL, explains:

“Everybody uses GPS to get from here to there. We have satellite television, we have weather reports, farmers use satellite data for monitoring crops. If you have a piece of satellite debris whacking into a satellite, in the worst case you now lose that capability.  In February of 2009, that actually happened where there was an Iridium communications satellite that collided with a dead Russian Kosmos satellite and so that basically took out a \$100 million dollar satellite.

There’s somewhere between 100,000 to 200,000 pieces of debris that we would like to be tracking. And so the supercomputing capabilities that we have here at Livermore are one way to keep track of that.”

This is a simulation of a rotating 4 dimensional Cube, otherwise known as a Tesseract.

What you are seeing is it Rotating. It is not being distorted, reshaped, or anything like that. it is simply Rotating - It appears to be distorted because you are only seeing the ‘projection’ of it. similarly if you rotated a 3D cube infront of lamp the shadow you would see would appear to distort.

oH MY GOD YOU GUYS

Safety first!

(via Buzzfeed on G+)

We never sit here under the weight of all this air, the 5 x 10^18 kg of atmosphere that sits above everyone on Earth, and say “Gosh, that sure is heavy!”

You don’t realize just how powerful that 1 bar (~100 kPa) of pressure is until a train car is filled with steam, allowed to cool, and then implodes ohmygod did that just happen?

For more implosion goodness, check out this awesome video from Veritasium.

Stellar Archaeology Traces Milky Way’s History

Unfortunately, stars don’t have birth certificates. So, astronomers have a tough time figuring out their ages. Knowing a star’s age is critical for understanding how our Milky Way galaxy built itself up over billions of years from smaller galaxies. But Jason Kalirai of the Space Telescope Science Institute and The Johns Hopkins University’s Center for Astrophysical Sciences, both in Baltimore, Md., has found the next best thing to a star’s birth certificate.

Using a new technique, Kalirai probed the burned-out relics of Sun-like stars, called white dwarfs, in the inner region of our Milky Way galaxy’s halo. The halo is a spherical cloud of stars surrounding our galaxy’s disk. Those stars, his study reveals, are 11.5 billion years old, younger than the first generation of Milky Way stars. They formed more than 2 billion years after the birth of the universe 13.7 billion years ago. Previous age estimates, based on analyzing normal stars in the inner halo, ranged from 10 billion to 14 billion years. Kalirai’s study reinforces the emerging view that our galaxy’s halo is composed of a layer-cake structure that formed in stages over billions of years.

White dwarf stars have remarkable properties, yet they are very simple. These stripped cores of normal hydrogen-burning stars are about 1 million times denser than matter on Earth. This means that a tablespoon of material from a white dwarf’s surface would weigh as much as a school bus on Earth. White dwarfs also have no fuel to generate energy, and most of their atmospheres contain a single atom, hydrogen.

The second figure illustrates the spectral features of a white dwarf, in comparison to the Sun and a blue giant. The white dwarf spectrum is simple, containing only absorption lines from the hydrogen atom. But, unlike the same lines in the blue giant spectrum (a bloated star with a low density), the features in the white dwarf are broadened due to the intense pressure on the surface of the star (essentially, the energy levels of the atom are being perturbed). This broadening of the lines, as well as their depth, is directly related to the mass and temperature of the star. Unlike for most stars, astronomers can therefore reliably establish fundamental properties for white dwarfs from their spectra.

Credit: NASAESA, and A. Feild and J. Kalirai (STScI)

At its best, philosophy can aid understanding. At its worst, its jargon supplies a handy toolkit for charlatans to bamboozle the innocent.

Richard Dawkins (via imagineatoms)

Quick clarification

If light has no mass how can it be affected by gravity?

Because it has momentum

But momentum is mass x velocity so how can it have momentum?

Because language can sometimes bring more problems than answers. Light does not obey the same laws as ordinary matter. To help show this I’ll use equations.

$E^2=P^2c^2+m^2c^4$ (this is the full version of the famous E=mc2
E=energy
P=momentum
c=speed of light
m=mass

So if we assume m=0 then we get E=Pc

We can find the energy of a photon by frequency x Planck’s constant (E=fh)

So if we know the energy and the speed of light (which is constant) then simple division will give us the momentum of the photon.

E/c=P

So gravity is related to momentum and not to mass?

Gravity is still determined by mass but in Relativity mass is determined by a stress-energy-momentum tensor. This tensor is what gives rise to the famous “curved spacetime”. If you would like to know about all of this and more in greater detail here is a fantastically well written Wikipedia