# Welt der Wissenschaft ;)

we are not alone !Today, we live in an age of exploration, where robots on Mars and planet-hunting telescopes are beginning to allow us to edge closer to an answer.

While we wait to establish contact, one technique we can use back on Earth is an equation that American astronomer Frank Drake formulated in the 1960s to calculate the number of detectable extraterrestrial civilizations may exist in the Milky Way galaxy.

It is not a rigorous equation, offering a wide range of possible answers. Instead it is more a tool used to help understand how many worlds might be out there and how those estimates change as missions like Kepler, a telescope that is currently searching for Earth-like planets, begin to discover more about our universe.

Until ground-based observations, space telescopes and planet-roving robots uncover any tell-tale signs of life, what better way to speculate on how many intelligent alien civilizations may exist than to explore the universe with our interactive version of the equation.

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(via sciencenote)

## Nikola Rahme

## Budapest, Hungary

Subject Matter:

Hymenoptera:Eupelmidae(parasitic wasp)(21.2x)Technique:

Dr. María Alejandra Lopez-Verrilli## Pontificia Universidad Católica de Chile

Facultad de Ciencias Biológicas

Santiago, ChileSubject Matter:

Radial growth of sensory neurons (axons stained in green, somas in blue and actin filaments in red)(4x)Technique:

(via medicinenotes)

## Zippering Up the Embryo

Advances in imaging tools and techniques have allowed scientists to image in real-time embryonic development in many model organisms, pushing the boundaries of what can be visualized. These advances have also contributed to overcoming some of the particular challenges inherent to following development in organisms that undergo gestation in utero. As seen here in a mouse embryo, the dynamics of the second step of neural tube closure–whereby the two edges of the cell sheet or neural fold “zip” together to form a closed tube–can be visualized in great detail. See also Massarwa and Niswander, 2013.

Image: Movie showing neural tube closure in a mouse embryo by time-lapsed confocal imaging. Actin is shown in green; time is in hours. Scale bar, 20 μm.

## Stephen S. Nagy, MD

## Montana Diatoms

Helena, Montana, USASubject Matter:

Antique microscope slide featuring thin section of diseased ivory

(15x)Technique:

In 1202, Italian mathematician

Leonardo Pisano(also known asFibonacci, meaning “son of Bonacci”) pondered the question: Given optimal conditions, how many pairs of rabbits can be produced from a single pair of rabbits in one year? Thisthought experimentdictates that the female rabbits always give birth to pairs, and each pair consists of one male and one female.Think about it — two newborn rabbits are placed in a fenced-in yard and left to, well, breed like rabbits. Rabbits can’t reproduce until they are at least one month old, so for the first month, only one pair remains. At the end of the second month, the female gives birth, leaving two pairs of rabbits. When month three rolls around, the original pair of rabbits produce yet another pair of newborns while their earlier offspring grow to adulthood. This leaves three pairs of rabbit, two of which will give birth to two more pairs the following month.

The order goes as follows: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 and on to infinity. Each number is the sum of the previous two. This series of numbers is known as the

Fibonacci numbersor theFibonacci sequence. The ratio between the numbers (1.618034) is frequently called thegolden ratioorgolden number.At first glance, Fibonacci’s experiment might seem to offer little beyond the world of speculative rabbit breeding. But the sequence frequently appears in the natural world — a fact that has intrigued scientists for centuries.

In string theory, as in guitar playing, the string must be stretched under tension in order to become excited. However, the strings in string theory are floating in spacetime, they aren’t tied down to a guitar. Nonetheless, they have tension. The string tension in string theory is denoted by the quantity 1/(2 p a’), where a’ is pronounced “alpha prime”and is equal to the square of the string length scale.

If string theory is to be a theory of quantum gravity, then the average size of a string should be somewhere near the length scale of quantum gravity, called thePlanck length, which is about 10^{-33}centimeters, or about a millionth of a billionth of a billionth of a billionth of a centimeter. Unfortunately, this means that strings are way too small to see by current or expected particle physics technology (or financing!!) and so string theorists must devise more clever methods to test the theory than just looking for little strings in particle experiments.

Do you need to be told about chaos, or is your desk a permanent example?As everyone knows, beneath what those intolerably neat and tidy people consider to be chaos, there is a form of order. The chaotic housekeeper can always find the item of their desire - as long as no-one tidies up!Many systems which scientists have considered totally random, unpredictable and without form have now been found to be otherwise. There is form and pattern hidden within the

CHAOS. It is a part of the natural form - a definitive ingredient of Nature itself.The Oxford Concise Dictionary defines chaos as

“Formless primordial matter; utter confusion.”The day has come when there is a need for an update -Chaos Theory is changing the way scientists look at the weather, the way mathematicians plot equations and the way artists define Art.Population dynamics is one area which can be very sensitive to small changes in initial conditions. So can the weather. A butterfly flapping its wings in a South American jungle, it is said, can lead to a hurricane in China. This is the signature of Chaos Theory!…

In playing with these ideas, a new way of doing science grew. These computers could not only calculate they could communicate too. Information flew around the globe. You no longer had to be in the right place or talk to the right people. The equipment and information was available to masses of people all over the world. And their mathematics produced images which were stunningly beautiful, and, at times, awesomely like nature.

A new art form was born and a whole new set of questions arose about the nature of nature itself. These images, called FRACTALS were fun. They had an ever growing fan club who became obsessed with their generation.