# 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.

hex: Saturn’s north pole, photographed by Cassini, 3rd April 2014.

The hexagon is an atmospheric vortex, the shape apparently created by interaction of winds circling the pole at different speeds. Each side of the hexagon is about 13,800km long, wider than Earth.

10 images taken over about a quarter of a Saturnian day, which is about 10 hours and 40 minutes long.

Image credit: NASA/JPL/SSI. Animation: AgeOfDestruction.

a length 550cm of thin thread wraps around a cylinder exactly 25 times. calculate the circumference and radius of the cylinder...

To get the circumference just divide the length of the thread by the number of times it wraps around the cylinder i.e. 550/25 = 22cm

To get the radius you first need to get the diameter of the cylinder. You can get this by dividing the circumference by the constant pi (3.1415926…) i.e. 22/π ≈ 7cm

since the diameter is 7cm, then the radius must be half that = 3.5cm

## Fact of the day

How long a star can stay shining depends on how massive it is - but it probably works the opposite way to how you’d expect! Even though less massive stars have a lot less hydrogen fuel to burn*, they still last much longer than more massive stars. How does that work?

It’s all because more massive stars have stronger gravity, which pulls them in tighter and compresses the core more. This raises temperatures and pressures in the star’s core, causing the nuclear fusion which powers the star to happen faster - much faster. More massive stars have more fuel, then, but they’re burning it much, much faster than less massive stars are, and will run out sooner. It’s a bit like a spendthrift millionaire spending all his money in one go vs. a careful student carefully budgeting every penny she spends. The millionaire will go broke faster.

The Sun has a predicted lifetime of around 11 billion years or so (so it has another 6 or so billion years left), but very massive stars (~40 times the mass of the Sun) can only live for one million years! And the least massive stars - tiny, dim, red dwarf stars only 80 times more massive than Jupiter - can stay shining for over a trillion years! That’s far, far longer than the age of the Universe, which means the earliest red dwarfs to form after the Big Bang are still with us and will be around long after our Sun is gone - and after several new generations of Sun-like stars have been able to form, live their lives and die as well!

What are the ingredients of an “all natural” banana?

Thanks to I F-ing Hate Pseudoscience

Just to make this entirely clear (the quotation marks on the “all natural” confused me) this is literally what a natural banana contains. These aren’t dangerous, synthetic chemicals, (not that synthetic chemicals are automatically dangerous), but they are found in nature and are perfectly safe in the context of a banana. The point of this image is to show that just because a substance may have an off-putting name, it doesn’t make it dangerous

Be aware of chemophobia and make sure you don’t fall into the trap!

## CERN to switch to Comic Sans

From today, all of CERN’s official communication channels are switching to exclusive use of the font Comic Sans. The move comes after weeks of deliberation by CERN management and top web designers about how best to update the image of the laboratory for this, its 60th anniversary year.
"This is an important year for CERN and we wanted to make a bold visual statement," says CERN Head of Communications James Gillies.

"We thought the most effective way to communicate our research into the fundamental structure of matter at the very boundaries of technology was by changing the font." For Gillies, Comic Sans says: ‘This is a serious laboratory, with a serious research agenda.’ - "And it makes the letters look all round and squishy," he adds.

(Source: astronemma)

## The universe does not behave according to our pre-conceived ideas. It continues to surprise us.

Stephen Hawking (via we-are-star-stuff)

(Source: inthenoosphere)

As we now know the Earth is round. Therefore, the challenge of any world map is to represent a round Earth on a flat surface. There are literally thousands of map projections and each has certain strengths and corresponding weaknesses, but the one you’re now picturing in your head most likely isn’t the area accurate representation.

The most widely used map today is the Mercator projection map. Mercator maps often appear in businesses, in libraries and in classrooms where geography is taught. This popularity is surprising, given the fact that the Mercator projection was first constructed in 1569. The more accurate representation of land mass is the Peters Projection Map:

Here’s a direct representation of the previously assumed factual map with the real flattened version:

The Peters Projection Map shows how Africa is larger than the combination of China, the US, Western Europe, India, Argentina, three Scandinavian countries and the British Isles.

Mercator maps show Europe as being larger than South America. In reality, South America is almost twice the size of Europe. Alaska appears to be three times larger than Mexico, although Mexico actually is larger than Alaska. Greenland looks roughly the same size as Africa, when, in fact, Africa is fourteen times larger than Greenland. Africa also looks considerably smaller than Russia, even though Africa is actually 33% larger.

To see how big the western countries have become, it’s hard to see how this has nothing to do with suppression; to make us believe they are ‘bigger’ and ‘on top’. A simple change in the look of a map can cause a reconsideration of your fixed ideas about a place.

Bonus:

2012 VP113: A new furthest known orbit in the solar system

What object has the furthest known orbit in our Solar System? In terms of how close it will ever get to the Sun, the new answer is 2012 VP113, an object currently over twice the distance of Pluto from the Sun. Pictured above is a series of discovery images taken with the Dark Energy Camera attached to the NOAO’s Blanco 4-meter Telescope in Chile in 2012 and released last week. The distant object, seen moving on the lower right, is thought to be a dwarf planet like Pluto. Previously, the furthest known dwarf planet was Sedna, discovered in 2003. Given how little of the sky was searched, it is likely that as many as 1,000 more objects like 2012 VP113 exist in the outer Solar System. 2012 VP113 is currently near its closest approach to the Sun, in about 2,000 years it will be over five times further. Some scientists hypothesize that the reason why objects like Sedna and 2012 VP113 have their present orbits is because they were gravitationally scattered there by a much larger object — possibly a very distant undiscovered planet.

Image credit: S. S. Sheppard (CIS) & C. Trujillo (Gemini Obs.), NOAO

(Source: apod.nasa.gov)

Women in Science Interactive

Women in Science, a new interactive tool, presents the latest available data for countries at all stages of development. Produced by the UNESCO Institute for Statistics, the tool lets you explore and visualize gender gaps in the pipeline leading to a research career, from the decision to get a doctorate degree to the fields of research women pursue and the sectors in which they work.

[Source]

## The press still thinks [global warming] is controversial. So they find the 1% of the scientists and put them up as if they’re 50% of the research results. You in the public would have no idea that this is basically a done deal and that we’re on to other problems, because the journalists are trying to give it a 50/50 story. It’s not a 50/50 story. It’s not. Period.

Neil deGrasse Tysonpodcast interview (via fourteendrawings)

(Source: descepter)

## The business of skepticism is to be dangerous. Skepticism challenges established institutions. If we teach everybody, including, say, high school students, habits of skeptical thought, they will probably not restrict their skepticism to UFOs, aspirin commercials, and 35,000-year-old channelees. Maybe they’ll start asking awkward questions about economic, or social, or political, or religious institutions. Perhaps they’ll challenge the opinions of those in power. Then where would we be?

Carl Sagan, The Demon Haunted World: Science as a Candle in The Dark (via thedragoninmygarage)

Sir David Frederick Attenborough

rich white straight cis man talking about controlling the population, fuck that

Are you fucking shitting me? He is a fucking naturalist, trying to educate people on why conservation, environmental management, and population control is necessary.
His gender, sexuality, class, or race has nothing to do with this.
Obviously you have not watched this program, or have understood the message. Shut the fuck up and go do some research.

(Source: joyfulpantsofbuttlol)

# How do rainbows form?

One of nature’s most splendid masterpieces is the rainbow. A rainbow is an excellent demonstration of the dispersion of light and one more piece of evidence that visible light is composed of a spectrum of wavelengths, each associated with a distinct color. To view a rainbow, your back must be to the sun as you look at an approximately 40 degree angle above the ground into a region of the atmosphere with suspended droplets of water or even a light mist. Each individual droplet of water acts as a tiny prism that both disperses the light and reflects it back to your eye. As you sight into the sky, wavelengths of light associated with a specific color arrive at your eye from the collection of droplets. The net effect of the vast array of droplets is that a circular arc of ROYGBIV is seen across the sky. But just exactly how do the droplets of water disperse and reflect the light? And why does the pattern always appear as ROYGBIV from top to bottom?

The Path of Light Through a Droplet

A collection of suspended water droplets in the atmosphere serves as a refractor of light. The water represents a medium with a different optical density than the surrounding air. Light waves refract when they cross over the boundary from one medium to another. The decrease in speed upon entry of light into a water droplet causes a bending of the path of light towards the normal. And upon exiting the droplet, light speeds up and bends away from the normal. The droplet causes a deviation in the path of light as it enters and exits the drop.

There are countless paths by which light rays from the sun can pass through a drop. Each path is characterized by this bending towards and away from the normal. One path of great significance in the discussion of rainbows is the path in which light refracts into the droplet, internally reflects, and then refracts out of the droplet. A light ray from the sun enters the droplet with a slight downward trajectory. Upon refracting twice and reflecting once, the light ray is dispersed and bent downward towards an observer on earth’s surface. Other entry locations into the droplet may result in similar paths or even in light continuing through the droplet and out the opposite side without significant internal reflection. But for the entry location shown in the diagram at the right, there is an optimal concentration of light exiting the airborne droplet at an angle towards the ground. As in the case of the refraction of light through prisms with nonparallel sides, the refraction of light at two boundaries of the droplet results in the dispersion of light into a spectrum of colors. The shorter wavelength blue and violet light refract a slightly greater amount than the longer wavelength red light. Since the boundaries are not parallel to each other, the double refraction results in a distinct separation of the sunlight into its component colors.

The angle of deviation between the incoming light rays from the sun and the refracted rays directed to the observer’s eyes is approximately 42 degrees for the red light. Because of the tendency of shorter wavelength blue light to refract more than red light, its angle of deviation from the original sun rays is approximately 40 degrees. There are a multitude of paths by which the original ray can pass through a droplet and subsequently angle towards the ground. Some of the paths are dependent upon which part of the droplet the incident rays contact. Other paths are dependent upon the location of the sun in the sky and the subsequent trajectory of the incoming rays towards the droplet. Yet the greatest concentration of outgoing rays is found at these 40-42 degree angles of deviation. At these angles, the dispersed light is bright enough to result in a rainbow display in the sky.

The Formation of the Rainbow

A rainbow is most often viewed as a circular arc in the sky. An observer on the ground observes a half-circle of color with red being the color perceived on the outside or top of the bow. Those who are fortunate enough to have seen a rainbow from an airplane in the sky may know that a rainbow can actually be a complete circle. Observers on the ground only view the top half of the circle since the bottom half of the circular arc is prevented by the presence of the ground (and the rather obvious fact that suspended water droplets aren’t present below ground). Yet observers in an airborne plane can often look both upward and downward to view the complete circular bow.

The circle (or half-circle) results because there are a collection of suspended droplets in the atmosphere that are capable concentrating the dispersed light at angles of deviation of 40-42 degrees relative to the original path of light from the sun. These droplets actually form a circular arc, with each droplet within the arc dispersing light and reflecting it back towards the observer. Every droplet within the arc is refracting and dispersing the entire visible light spectrum (ROYGBIV). As described above, the red light is refracted out of a droplet at steeper angles towards the ground than the blue light. Thus, when an observer sights at a steeper angle with respect to the ground, droplets of water within this line of sight are refracting the red light to the observer’s eye. The blue light from these same droplets is directed at a less steep angle and is directed along a trajectory that passes over the observer’s head. Thus, it is the red light that is seen when looking at the steeper angles relative to the ground. Similarly, when sighting at less steep angles, droplets of water within this line of sight are directing blue light to the observer’s eye while the red light is directed downwards at a more steep angle towards the observer’s feet. This discussion explains why it is the red light that is observed at the top and on the outer perimeter of a rainbow and the blue light that is observed on the bottom and the inner perimeter of the rainbow.

Rainbows are not limited to the dispersion of light by raindrops. The splashing of water at the base of a waterfall caused a mist of water in the air that often results in the formation of rainbows. A backyard water sprinkler is another common source of a rainbow. Bright sunlight, suspended droplets of water and the proper angle of sighting are the three necessary components for viewing one of nature’s most splendid masterpieces.

[source]

SCIENTISTS, by artist Alan Kennedy on Flickr

• Galileo Galilei and the moons of Jupiter
• Isaac Newton: the motion of objects and spectrum of light
• Charles Darwin and descent with modification via natural selection
• Nicola Tesla and the age of electricity
• Albert Einstein and spacetime