mothernaturenetwork:

Fin whale’s big gulp aided by newly discovered organ
The size of a grapefruit, the newly discovered organ is full of nerves that detect changes in ocean pressure to let whales know when to open their mouths.

ylimenospmoht:

pretendy:

Why is the night sky dark?

This is a question that at first sounds a bit stupid, but the observation that the night sky is dark is in fact a deeply profound one that provides much of the basis for modern cosmology.

The question which has now come to be known as Olbers’ paradox goes something like this: “In an infinite and static universe with an infinite amount of stars, why is the night sky dark?”

Why?

The argument was that if you looked at any point in the sky and drew your line of sight, it would eventually reach a star. In other words, along every possible direction, there should be a star, and hence light should be coming from every point in the sky.

No, really, why?

This is a bit of a wishy-washy argument when posed in terms of words, so let’s try some maths:

Imagine that throughout the universe, the density of stars (number per cubic lightyear, say), let’s call it n, remains roughly constant. Now, imagine that we construct a series of spherical shells surrounding the Earth, and that each has a thickness dr. See the main picture to see what I mean.

What we want to do is count up the number of stars, N, in a shell. For a shell a distance r away, we multiply its volume by the star density:

Now let’s work out how bright that shell is. We can assume that each star has a total luminosity of L, but we have to take into account the fact that the further away a star is the fainter it appears. In fact, the apparent brightness, F, of any star varies like:

The brightness of a thin shell - which we’ll call dJ- is just the number of stars times the brightness of each!

Now we integrate over all space, i.e., add up the contribution from every consecutive shell all the way to infinity.

In other words, the total brightness of the sky, J, is infinite!

Okay but WHY?

The essential reason for this is the fact we said that the brightness of a star decreased by an inverse square law, but the number of stars increased by a regular square law. The two r^2 terms cancelled each other out and we found that each shell had the same brightness! Therefore when you add up an infinite number of same-brightness shells the answer you get is ∞.

Oh. So?

Well, this is obviously not true when we look up at the sky, so there must be a problem somwhere. Like most things in science, the problem lies within our initial assumptions, namely: ‘the universe is static and infinite’. We have shown that this just can’t be true! The night sky being dark forces the universe to have a finite size and age!

Edgar Allen Poe was eerily accurate when he postulated that no light reaches Earth from beyond a certain distance - corresponding to the age of the oldest stars. Cosmology caught on to this idea and introduced the concepts of the big bang, universal expansion, and the cosmic horizon in order to account for this seemingly trivial darkness problem.

Think of this next time you look at a starry sky. We see faint objects as they were hundreds, thousands, millions and billions of years ago (the time it has taken light from them to reach our eyes). At the farthest depths of what our most powerful telescopes can make out are objects from the beginning of the universe itself, and beyond that… nothing.

We can see the edge. It’s black.

Cool.

laboratoryequipment:

There Are Multiple Paths to One Supernova

The exploding stars known as Type Ia supernovae serve an important role in measuring the universe, and were used to discover the existence of dark energy. They’re bright enough to see across large distances, and similar enough to act as a “standard candle” - an object of known luminosity. The 2011 Nobel Prize in Physics was awarded for the discovery of the accelerating universe using Type Ia supernovae. However, an embarrassing fact is that astronomers still don’t know what star systems make Type Ia supernovae.

Two very different models explain the possible origin of Type Ia supernovae, and different studies support each model. New evidence shows that both models are correct - some of these supernovae are created one way and some the other.

Read more: http://www.laboratoryequipment.com/news-There-Are-Multiple-Paths-to-One-Supernova-Type-050812.aspx

jtotheizzoe:

Tesla - From Faust to Master of Lightning

Pictured above is one of Nikola Tesla’s original induction motors, a marvel of invention that harnesses alternating current to create mechanical power. The term “world-changing invention” gets thrown around a lot, but this certainly qualifies.

But its inspiration has an unexpected genesis. One day, while walking through a park in Budapest, the young Tesla was reciting a poetic passage by heart (one of his many talents). From Goethe’s Faust:

The glow retreats, done is the day of toil;
It yonder hastes, new fields of life exploring;
Ah, that no wing can lift me from the soil
Upon its track to follow, follow soaring!

And as the sun set that day, with its glow retreating, Tesla is said to have drawn the design for the induction motor in the sand.

Creativity, scientific or otherwise, is nourished by diverse influences. Keep your ears and eyes open.

(via PBS)

jtotheizzoe:

A Duplicate Gene May Have Helped Our Brains Become “Human”

Among the ~25,000 or so genes in our genome, we find a handful of duplicates. Some of them, like the genes that make pieces of the ribosome (your cellular protein factories) are fully-functional exact copies. This allows your cells to make a whole mess of that gene product. But other duplicates are imperfect copies put there by accidents or errors, and often those copies can be a bit wonky. 

One of those imperfect gene copies may have had a strong influence on our brains becoming more advanced and “human” during evolution. A group led by Evan Eichler looked at a gene called SRGAP2 and noted that it appeared to have been duplicated to a certain form about 2.4 million years ago, which is when the Homo lineage split from Australopithecus. That duplicate, called SRGAP2C, actually overpowers the function of the original gene.

Even cooler, when Franck Polleux at Scripps expressed that SRGAP2C in mice, it made their neurons look a lot more human! So perhaps when this imperfect duplicate popped up in our genome, it changed the way our neurons developed (as shown in the picture above). If those changes were significant enough, they could have helped our larger and more advanced Homo brains evolve beyond our simpler ancestors! It’s too early to make that claim just yet, but it’s a very cool idea.

This also means that because our neurons develop in a way that is so different from mice, we should reconsider whether they are a good model for disorders like autism. We may be looking at a brain that’s just too different from our own at its core.

For more, Ed Yong has some good coverage of this on his blog.

jtotheizzoe:

Ambigram duality.

the-star-stuff:

Curling Physics Unraveled

Researchers know why ribbons and hairs curl, but few have examined the dynamics of an object going from straight to curled up. A study in Physical Review Letters looks at the simple case of a curved metal strip that is straightened and then released. Using a combination of experiments, numerical simulations, and mathematical analysis, the research team has performed a complete study on the shape and speed of the strip as it curls. The work provides a basic framework for explaining curling in future micromachines or in the splitting open of a red blood cell.

Image by P.-T. Brun & B. Audoly/CNRS