Stars, the Sky and Love


Stars

What Happens


onceupunatimeredJennifer had begun working for her Phd in Theoretical Physics.

Her major interest was in what changes differing events may bring about at both macro and micro levels.

The research group she was working with was attempting to find links between the theoretical and physical events.

After a hard Thursday, she was hanging up her white coat and putting her clipboard into her locker when her group leader told her that tomorrow was Friday and was designated as Causal Friday.

“Causal Day?” Jennifer asked.

“Yes,” replied her boss. “Everything we do will have effects.”

Science Fact of the Week


deer

The Climate Change Conundrum


There is a big warning brought to you by;

The same people who gave you the computer.

The same people who gave the world the atomic bomb

The same people who put the digital watch on your wrist.

The same people who wiped smallpox from the face of the Earth.

The same people who gave baby incubators to hospitals.

The same people who gave you Sputnik and world-wide communications.

The same people who gave you the vaccines which save millions of lives every year.

The same people who create the highest buildings in the world.

The same people who created the aircraft in which you fly.

The same people who gave you organ transplants.

The same people who gave you electricity.

The same people who build the bridges you drive over.

The same people who save lives by exposing the dangers of smoking.

The same people who gave you airconditioning on a hot day.

 

The scientists and engineers who train for years.

The people you trust with your life every day.

Yet you deny these same people when thay warn you of Climate Change.

Yet you deny these same people when they warn you that civilisation is at risk.

Yet you deny these same people when they warn that humans may go extinct.

 

And you won’t be around to apologise to your great grand children!

Tim Flannery’s Fate


science

The Most Awesome Thing I Have Seen Today


Science is wonderful

But applied science is awesome!

Terrible Tyrannosaurus


 

Burgled from Fake Science

Pessimist or Optimist?


Glass Half Empty

What if a glass of water was, all of a sudden, literally half empty?

The pessimist is probably more right about how it turns out than the optimist.

When people say “glass half empty”, they usually mean something like a glass containing equal parts water and air:

an optimist and pessimist sitting at a table with a half-full - or half-empty glass between them. the optimist's thought bubble reads 'ooh-water! i bet we'll get to drink it!' while the pessimist's thought bubble reads 'drinking fluids postpones detah but doesn't avert it.'Traditionally, the optimist sees the glass as half full while the pessimist sees it as half empty. This has spawned a zillion joke variants—e.g., the engineer sees a glass that’s twice as big as it needs to be, the surrealist sees a giraffe eating a necktie, etc.

But what if the empty half of the glass were actually empty—a vacuum? (Even a vacuum arguably isn’t truly empty, but that’s a question for quantum semantics.)

The vacuum would definitely not last long. But exactly what happens depends on a key question that nobody usually bothers to ask: Which half is empty?

For our scenario, we’ll imagine three different half-empty glasses, and follow what happens to them microsecond by microsecond.

three half-empty glasses of waterIn the middle is the traditional air/water glass. On the right is a glass like the traditional one, except the air is replaced by a vacuum. The glass on the left is half full of water and half empty—but it’s the bottom half that’s empty.

We’ll imagine the vacuums appear at time t=0.

three half-empty glasses of water at t=0For the first handful of microseconds, nothing happens. On this timescale, even the air molecules are nearly stationary.

three half-empty glasses of water at t=50nsFor the most part, air molecules jiggle around at speeds of a few hundred meters per second. But at any given time, some happen to be moving faster than others. The fastest few are moving at over 1000 meters per second. These are the first to drift into the vacuum in the glass on the right.

The vacuum on the left is surrounded by barriers, so air molecules can’t easily get in. The water, being a liquid, doesn’t expand to fill the vacuum in the same way air does. However, in the vacuum of the glasses, it does start to boil, slowly shedding water vapor into the empty space.

three half-empty glasses at t=150nsWhile the water on the surface in both glasses starts to boil away, in the glass on the right, the air rushing in stops it before it really gets going. The glass on the left continues to fill with a very faint mist of water vapor.

three half-empthy glasses at t=400nsAfter a few hundred microseconds, the air rushing into the glass on the right fills the vacuum completely and rams into the surface of the water, sending a pressure wave through the liquid. The sides of the glass bulge slightly, but they contain the pressure and do not break. A shockwave reverberates through the water and back into the air, joining the turbulence already there.

three half-empty glasses at t=1msThe shockwave from the vacuum collapse takes about a millisecond to spread out through the other two glasses. The glass and water both flex slightly as the wave passes through them. In a few more milliseconds, it reaches the humans’ ears as a loud bang.

three half-empty glasses at t=2msAround this time, the glass on the left starts to visibly lift into the air.

The air pressure is trying to squeeze the glass and water together. This is the force we think of as suction. The vacuum on the right didn’t last long enough for the suction to lift the glass, but since air can’t get into the vacuum on the left, the glass and the water begin to slide toward each other.

three half-empty glasses at t=5msThe boiling water has filled the vacuum with a very small amount of water vapor. As the space gets smaller, the buildup of water vapor slowly increases the pressure on the water’s surface. Eventually, this will slow the boiling, just like higher air pressure would.

three half-empty glasses at t=8msHowever, the glass and water are now moving too fast for the vapor buildup to matter. Less than ten milliseconds after the clock started, they’re flying toward each other at several meters per second. Without a cushion of air between them—only a few wisps of vapor—the water smacks into the bottom of the glass like a hammer.

three half-empty glasses at t=10msWater is very nearly incompressible, so the impact isn’t spread out—it comes as a single sharp shock. The momentary force on the glass is immense, and it breaks.

This “water hammer” effect (which is also responsible for the “clunk” you sometimes hear in old plumbing when you turn off the faucet) can be seen in the well-known party trick (recorded on Mythbusters, analyzed in physics classes, and demonstrated in countless student dorms) of smacking the top of a glass bottle to blow out the bottom.

When the bottle is struck, it’s pushed suddenly downward. The liquid inside doesn’t respond to the suction (air pressure) right away—much like in our scenario—and a gap briefly opens up. It’s a small vacuum—a few fractions of an inch thick—but when it closes, the shock breaks the bottom of the bottle.

In our situation, the forces would be more than enough to destroy even the heaviest drinking glasses.

three half-empty glasses at t=20msThe bottom is carried downward by the water and thunks against the table. The water splashes around it, spraying droplets and glass shards in all directions.

Meanwhile, the detached upper portion of the glass continues to rise.

three half-empty glasses at t=500ms zoomed out to the table with the optimist (thinking 'Coool!') and the pessimist (thinking 'uh oh.')After half a second, the observers, hearing a pop, have begun to flinch. Their heads lift involuntarily to follow the rising movement of the glass.

two half-empty glasses on the table at t=1s, the third glass breaking into fragments The glass has just enough speed to bang against the ceiling, breaking into fragments…

two half-empty glasses on the table at t=1.5s, the third glass now a mass of fragments raining down from the ceiling.… which, their momentum now spent, return to the table.

two half-empty glasses on the table at t=10s, the third now embedded in the faces of the optimist ('Hey, free glass!') and pessimist ('Aaaaaaa')The lesson: If the optimist says the glass is half full, and the pessimist says the glass is half empty, the physicist ducks.

the glass-studded optimisit pours water from one of the remaining half-empty glasses into the other. the pessimist's chair is empty.

Mars Landers


Burgled from xkcd

Do You Understand The Higgs Boson?


Shamelessly burgled from Fake Science

A Mole of Moles


Randall has amused me for years with his xkcd cartoons.

We all tend to forget that he is also a sciency geek!

Now he is going back to his roots and finding new ways to teach important science. He takes the approach of “What If – - – -”

Here is an example. Click on the image for more details. More GRUESOME details!

His Flying Bosonic Noodleness


Thank you, Email, for your ever-giving generosity.

I Want Want Want!


How good would this be for Christmas Presents?

I have offspring and offspring’s offspring who would love this!

Available from here - but there is only one left!

 

Climate Change; Perception vs Media vs Facts


Thank goodness for Emails  :)

Why Do Cats Purr?


Burgled from Fake Science
Follow

Get every new post delivered to your Inbox.

Join 2,783 other followers