Posts about why

StoryCorps: Passion for Mechanical Engineering

StoryCorps is an effort to record and archive conversations. NPR plays excerpts of one of the conversations each week, and they are often inspiring. They are conversation between two people who are important to each other: a son asking his mother about her childhood, an immigrant telling his friend about coming to America, or a couple reminiscing on their 50th wedding anniversary. By helping people to connect, and to talk about the questions that matter powerful recording are made. Yesterday I heard this one – A Bent For Building, From Father To Daughter:

“Can a girl be an engineer?” she asked her father. His answer: There was no reason she couldn’t.

Anne loved to take her things apart. It was mostly her toys — until the day she took a clock apart and spread its contents out.

When her father asked what had happened, his daughter answered, “Oh, I took it apart. Daddy fix.”

And as her dad put things back together, Anne would sit by, watching intently to see how things were made. “Did you ever notice that I always followed you around the shop, watching?” Anne asked Ledo.

“I thought there was a magnet hooked up to me and to you.”

Related: Tinker School: Engineering CampSarah, aged 3, Learns About SoapWhat Kids can LearnColored Bubbles

How Cells Age

How Cells Age

A new study by Harvard Medical School researchers reveals that the biochemical mechanism that makes yeast grow old has a surprising parallel in mice, suggesting it may be a universal cause of aging in all organisms.

In young organisms, SIRT1 effectively doubles as a gene-expression regulator and a DNA repairer. But when DNA damage accumulates—as it does with age—SIRT1 becomes too busy fixing broken DNA to keep the expression of hundreds of genes in check. This process is so similar to what happens in aging yeast that its discoverers believe it may represent a universal mechanism of aging.

Harvard researchers gain new insight into aging

Aging may be a case of neglect — an absentee landlord at the cellular level that allows gene activity to go awry, according to a study published today.

Scientists have long known that aging causes gene expression to change, and DNA damage to accumulate. But now, research led by Harvard Medical School scientists explains the connection between the two processes in mammals.

The paper, published in the journal Cell, found that a multi-tasking protein called SIRT1 that normally acts as guardian of the genome gets dragged away to DNA fix-it jobs. When the protein abandons its normal post to work as a genetic handyman, order unravels elsewhere in the cell. Genes that are normally under its careful watch begin to flip on.

“What this paper actually implies is that aspects of aging may be reversible,” said David Sinclair, a Harvard Medical School biologist who led the research. “It sounds crazy, but in principle it should be possible to restore the youthful set of genes, the patterns that are on and off.”

The study is just the latest to draw yet more attention to sirtuins, proteins involved in the aging process

Aging is fascinating. By and large people just accept it. We see it happen to those all around us, without exception. But what causes biological aging? It is an interesting area of research.

Related: lobsters show no apparent signs of agingOur Genome Changes as We AgeMillennials in our Lifetime?Radical Life Extensionposts on cells

Why is it Colder at Higher Elevations?

John Hunter at Hurricane Ridge in Olympic National Park

I know it is colder at higher elevations (there is snow on the top of mountains when no snow is left on the bottom). When I was hiking this summer in Colorado and it started snowing I thought about why it was colder in higher elevations. My guess was that it was mainly due to lower air pressure and being higher up in the atmosphere where air was cooler than is was closer to sea level.

So I did some research online and the main explanations seem to be that at higher elevations the air pressure is lower (molecules and atoms under less pressure move more slowly which means the temperature is less).

Hot air does rise, but the amount of hot air is minor compared to the existing cold air in the atmosphere. So when hot air rises from the ground it is cooled down before getting far off the earth’s surface. And as it rises the pressure decreases, which cools it down.

Mountain Environments report, United Nations Environment Programme:

Air temperature on average decreases by about 6.5° C for every 1,000 m increase in altitude; in mid latitudes this is equivalent to moving poleward about 800 km. The dry dust-free air at altitude retains little heat energy, leading to marked extremes of temperature between day and night.

Photo of John Hunter at Hurricane Ridge in Olympic National Park.

Related: Why is the air cooler at higher altitudes?Why is the Sky Blue?scientific explanations for what we experienceFlint and Steel: What Causes the Sparks?Mount Rainier National Park PhotosLow air pressure decreases temps at high elevation
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Do Dolphins Sleep?

Do dolphins sleep?, MIT:

Dolphins do sleep, but not quite in the same way that people do. They sleep with one half of the brain at a time and with one eye closed. Dolphins rest this way on and off throughout the day, switching which side of the brain they shut down. During these periods, everything inside the dolphin slows down, and the mammal moves very little.

Related: Why do We Sleep?Energy Efficiency of Digestioninteresting science factsWhy is the Sky Blue?

Why ‘Licking Your Wounds’ Works

Why ‘Licking Your Wounds’ Actually Works

scientists found that histatin, a small protein in saliva previously only believed to kill bacteria was responsible for the healing.

To come to this conclusion, the researchers used epithelial cells that line the inner cheek, and cultured in dishes until the surfaces were completely covered with cells. Then they made an artificial wound in the cell layer in each dish, by scratching a small piece of the cells away.

In one dish, cells were bathed in an isotonic fluid without any additions. In the other dish, cells were bathed in human saliva. After 16 hours the scientists noticed that the saliva treated “wound” was almost completely closed. In the dish with the untreated “wound,” a substantial part of the “wound” was still open. This proved that human saliva contains a factor which accelerates wound closure of oral cells.

Because saliva is a complex liquid with many components, the next step was to identify which component was responsible for wound healing. Using various techniques the researchers split the saliva into its individual components, tested each in their wound model, and finally determined that histatin was responsible.

YouTube Access Denied

Millions of users around the globe could not access YouTube for a couple hours yesterday. Why?

Well to understand, we need to start with how you normally connect to a web site. You click on a link to Your ISP looks up the internet address for by looking at internet routing tables. Each domain has a name server that provides the IP address for where it should be found (for example, an IP address that shows is

Well what happened in this case is Pakistan decided to prevent anyone in Pakistan from accessing YouTube because the government didn’t like some video. The way Pakistan decided to accomplish this was to update their routing table to just direct all traffic that was meant to go to YouTube to a phony address which would then return nothing.

Why did many outside of Pakistan lose access to YouTube? Well their version of the routing table leaked out of Pakistan through PCCW (large internet provider), Then other internet providers adopted the incorrect information, until many around the globe were being directed to the wrong place.

You might find it amazing the routing system could allow such a thing to happen – it doesn’t seem very secure. You are right, that it doesn’t seem very sensible. When the internet was created some protocols were established that made sense then but don’t necessarily make sense for what the internet has become.

The problem was fixed when Google’s YouTube engineers contacted PCCW to inform them of the problem and have them correct it. I think if it was my site instead, I would have had difficulty figure out what was going on 🙂 Once PCCW corrected their routing tables the fixed flowed through the system and everyone was able to see the great stuff like Marissa Mayer discussing Innovation at Google.

I would imagine Internet2 (well on its way to a computer near you) and IPv6 will take not be so venerable to such a mistake.

Related: Insecure routing redirects YouTube to PakistanYouTube outage blamed on PakistanYouTube Censorship Sheds Light on Internet TrustThe Web is 15 Years OldInternet Undersea CablesHarvard Course: Understanding Computers and the InternetNet NeutralityThe Next Generation InternetThe Journey of Internet Packetsmistake proofing (the opposite of the current setup)

Scientists Search for Clues To Bee Mystery

Honey Bees Give Clues on Virus Spread by Carl Zimmer

Now, as farmers wait anxiously to see if the honeybees will suffer again this spring, the true cause of CCD remains murky. Skeptics have raised many reasons to doubt that Australian viruses are to blame. In Australia, bees that get Israeli acute paralytic virus don’t get sick, and the country has had no reports of CCD. And in places where honeybee colonies are collapsing — Greece, Poland, Spain — there are no imported Australian bees. These are not the sort of patterns you’d expect, the skeptics say, if Australian viruses were killing American bees.

Whether scientists look inside a honeybee or look at the entire biosphere, nature is proving to be awesomely intricate. In the oceans and the soil, metagenomics is revealing millions of different kinds of microbes, with an almost inconceivable diversity of viruses shuttling between them, carrying genes from host to host. But we have almost no idea how these menageries work together, either in the biosphere or inside a host like a honeybee — or a human. Many of the microbes that metagenomics is revealing are entirely new to science. As genetic databases fill with DNA sequences from millions of new species, our scientific wisdom lags far behind.

How true. Watching as scientists try to work out what is going on with Colony Collapse Disorder is a great lesson in how scientists search for answers. As I stated earlier much of science is not about simple obvious truths but a search through confusing signs to try and determine what is going on. Answering why, is not always so easy as it appears when someone has already found the answer and posted it online.

Related: Virus Found to be One Likely Factor in Bee Colony Collapse DisorderBee Colony Collapse DisorderMore on Disappearing Honeybeesmost Carl Zimmer related posts

Science Explains: Flame Color

Have you ever wondered why some flames are yellow, while others are blue? Growing up, I was always told that it was a matter of temperature, that hot flames were blue and cooler flames were yellow. While there is a temperature difference, that difference is a “symptom” of what is going on, not the cause of the color difference.

Does that mean that there is solid stuff inside the candle flame? Let’s find out. Light the candle and be sure it is steady and won’t fall over. Hold the bottom of the plate in the candle flame for a few seconds. When you remove the plate, it has turned black!!! Don’t worry. You have not ruined it. Let it cool for a minute. Remember, it is HOT! Once it has cooled, rub your finger over the black spot. The black rubs off.

Related: Science Explained: What The Heck is a Virus?Why is the Sky Blue?Frozen Images

Science Explained: What The Heck is a Virus?

What The Heck is a Virus? [removed broken link]

A virus is not strictly alive.. nor is it strictly dead… A virus has some fundamental information (genes made of DNA or RNA) which allows it to make copies of itself. However, the virus must be inside a living cell of some kind before the information can be used. In fact, the information won’t be made available unless the virus enters a living cell. It is this entrance of a virus into a cell which is called a viral infection. Too, the virus is very, very small relative to the size of a living cell. Therefore, the information the virus can carry is actually not enough to allow it to make copies (replicate). The virus uses the cell’s machinery and some of the cell’s enzymes to generate virus parts which are later assembled into thousands of new, mature, infectious virus which can leave the cell to infect other cells.

Related: What Are Viruses?Science Summary: PhotosynthesisAmazing Science: RetrovirusesUsing Bacteria to Carry Nanoparticles Into Cells

Why is the Sky Blue?

Here is a a nice post explaining why we see blue when we look at the sky, Why Is The Sky Blue?:

Most of the atmospheric gases are transparent to visible light. They don’t filter the Sun’s light and make it yellow, as a yellow filter would. Besides, if colored gases made the Sun appear yellow, where does the blue come from? The part of the atmosphere that changes the Sun’s light is the molecules and tiny particles that are floating in it.

There are particles of water–tiny droplets too small to be seen as clouds. There are particles of organic material–smog or haze, condensed from volatile organic chemicals that have gotten into the air. There are particles of sulfuric acid from volcanoes and power plants. There are molecules of gases in the atmosphere.

These tiny particles, much smaller than the wavelengths of sunlight, scatter the sunlight as photons from the Sun interact with the particles. This is called Rayleigh scattering after the British physicist who described how it works. (Larger particles, like the water droplets in clouds, are closer to the wavelengths of sunlight, and they scatter it differently. This is why clouds are not blue.)

Science explained – quick overviews of scientific concepts: How Does That Happen? Science Provides the AnswerIncredible Insects10 Science Facts You Should KnowWhat Everyone Should LearnScience Summary: PhotosynthesisString Theory in 1 pageHow do antibiotics kill bacteria?

Why do We Sleep?

Study puts us one step closer to understanding the purpose of sleep:

Sleep remains one of the big mysteries in biology. All animals sleep, and people who are deprived of sleep suffer physically, emotionally and intellectually. But nobody knows how sleep restores the brain.

Although an electronic power-napper sounds like a product whose time has come, Tononi is chasing a larger quarry: learning why sleep is necessary in the first place. If all animals sleep, he says, it must play a critical role in survival, but that role remains elusive.

Based on the fact that sleep seems to “consolidate” memories, many neuroscientists believe that sleeping lets us rehearse the day’s events.

Tononi agrees that sleep improves memory, but he thinks this happens through a different process, one that involves a reduction in brain overload. During sleep, he suggests, the synapses (connections between nerve cells) that were formed by the day’s learning can relax a little.