explore-blog:

For legendary physicist Richard Feynman’s birthday, his fascinating biography as a graphic novel.

(Source: )

How do rockets move in space?

If space is basically a vacuum and void of atmosphere, how do rockets alter the direction and speed of space craft? In other words, how do they “push off” against nothing?

This is a very good question. Isaac Newton worked out the solution and published it in 1687 in his Principia Mathematica. It is phrased as Newton’s 3rd law. I’ll include all 3 below just in case!

1st: A body will remain at rest or at motion with a uniform speed unless it is acted on my an external force. 2nd: The acceleration of a body with a force acting on it is that force divided by the mass of the body (F=ma) 3rd: Every action has an equal and opposite reaction.

So the third law basically says that if you shoot out stuff in one direction you will move in the other direction. This is how rockets work in a vacuum. They have a source of fuel which is heated up so that it expands and is pushed out of the rocket. In order to change direction in space rockets have to have little ‘thrusters’ on all sides (you need 6 in total to maneuver completely in 3 dimensions).

Newton’s 3rd law seems contrary to our intuition because on Earth there are lots of sources of friction - providing much easier methods of propulsion, however you might have seen it in action if you have ever blown up a balloon and then let go of it before tying it up. What pushes the balloon all around the room is the air you blew into in escaping.

(via scinerds)

brookhavenlab:

Renate Chasman was probably thinking about new ways to revolutionize particle accelerators when this photo was taken.

She was only in her early 40s when she and her collaborator, Ken Green, changed the way science in their field was done. Their ingenious Chasman-Green lattice manipulated accelerated electrons to produce the brightest x-rays ever created up to that time.  Completed in the 1970s, their design was first used at Brookhaven’s National Synchrotron Light Source, and then went on to be incorporated into future synchrotron light source facilities all around the world.

Chasman was one of the few female accelerator physicists of her time, and she has an interesting story. She was born in Berlin in 1932 and moved with her family to Holland and then Sweden after the Nazis came to power. As a child in Sweden, she would sometimes travel the three miles to school on skis. She studied nuclear physics at the Hebrew University of Jerusalem, then went on to work at Columbia University and Yale University, and finally she came to Brookhaven National Lab, where she found an interest in accelerator technology and ultimately revolutionized the field.

Just a few years after her profound contribution to science, this renowned physicist passed away in 1977 at the tragically young age of 45, but her legacy of innovation continues here at the Lab. Brookhaven Women in Science offers a scholarship in Chasman’s name that has promoted the advancement of women in scientific and technical careers for 27 years.

ikenbot:

International Efforts Accurately Measure Black Hole’s Spin for First Time: It’s Near The Speed of Light

Astronomers have recently been able to finely measure the spin of a supermassive Black hole and as expected, it’s really really fast, near light speed fast:

The black hole in question resides 60 million light years away at the centre of the NGC 1365 spiral galaxy, is a mind-boggling 3.2 million kilometres in diameter, has a mass two million times that of our Sun and is spinning at a rather impressive 1.08 billion km/h. Astronomers can now say this with confidence, after combining the efforts of Nasa’s Nuclear Spectroscopic Telescope Array (Nustar) — which measures high-energy X-rays — and the European Space Agency’s XMM-Newton, which measures low-energy X-rays.

The former was launched in June 2012 to track and measure the highest energy events in space. However, without the aid of ESA’s device, it was unable to determine whether the measurements of warped X-rays being taken were a result of nearby gas clouds manipulating results, or the black hole’s own gravitational pull.

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The find is an important one, because it helps astronomers understand the life of a black hole — which stretches, pulls on and distorts space, and can affect the evolution of galaxies — which in turn helps test the accuracy of Einstein’s theory of relativity, which argues that gravity can bend space and time.

“The black hole’s spin is a memory, a record, of the past history of the galaxy as a whole,” Guido Risaliti of the Harvard-Smithsonian Centre for Astrophysics, the lead author of a paper revealing the results, said in a statement.

Journal Reference: Nature

For more on Black Holes and Astrophysics.

(via mothernaturenetwork)

scienceisbeauty:

Physics of the Eye (via Connexions)

Further reading: How Vision Works.

(via scientificillustration)

mothernaturenetwork:

Has dark matter finally been found?

A forthcoming paper represents a ‘small step’ in figuring out what dark matter is, and perhaps not the final answer.

fuckyeahfluiddynamics:

In the collage above, successive frames showing the bouncing and break-up of liquid droplets impacting a solid inclined surface coated with a thin layer of high-viscosity fluid have been superposed. This allows one to see the trajectory and deformation of the original droplet as well as its daughter droplets. The impacts vary by Weber number, a dimensionless parameter used to compare the effects of a droplet’s inertia to its surface tension. A larger Weber number indicates inertial dominance, and the Weber number increases from 1.7 in (a) to 15.3 in (d). In the case of (a), the impact of the droplet is such that the droplet does not merge with the layer of fluid on the surface, so the complete droplet rebounds. In cases (b)-(d), there is partial merger between the initial droplet and the fluid layer. The impact flattens the original droplet into a pancake-like layer, which rebounds in a Worthington jet before ejecting several smaller droplets. For more, see Gilet and Bush 2012. (Photo credit: T. Gilet and J. W. M. Bush)

Death By Black Hole Firewall Incineration It Shall Be: “Oh, and if, say, an astronaut happened to accidentally cross the event horizon, he or she would technically be in freefall and thus wouldn’t notice anything particularly unusual — not at first. It’s only as said astronaut approached the singularity that gravity would become so extreme, s/he would be “spaghettified.” Except now that might not be the case. There’s a hypothesis currently being bandied about by theoretical physicists that, instead, the unfortunate astronaut would encounter a massive wall of fire as s/he tried to cross the event horizon and burn up before s/he got anywhere near the singularity. Call it the ‘Paradox of the Firewall.’”

An entirely different kind of unpleasant death by black hole! The universe is a seriously wonderous place to die.

(via discoverynews)