xkcd: What If?

[bystander]

Hockey Puck

• How hard would a puck have to be shot to be able to knock the goalie himself backwards into the net? — Tom

[bystander]

Pressure Cooker

• Am I right to be afraid of pressure cookers? What's the worst thing that can happen
  if you misuse a pressure cooker in an ordinary kitchen? — Delphine Lourtau

[geckzilla]

You're doing it wrong if you don't end up with a nice cheesecake at the end.

[bystander]

Go West

• If everybody in the US drove west, could we temporarily halt continental drift? — Derek

[neufer]

Go West

<<"Go West, young man" is a quote by American author Horace Greeley concerning America's expansion westward, related to the then-popular concept of Manifest Destiny. Some sources have claimed the phrase is derived from the following advice in Greeley's July 13, 1865 editorial in the New York Tribune, but this text does not appear in that issue of the newspaper. The actual editorial instead encourages Civil War veterans to take advantage of the Homestead Act and colonize the public lands: “Washington is not a place to live in. The rents are high, the food is bad, the dust is disgusting and the morals are deplorable. Go West, young man, go West and grow up with the country.” —- Horace Greeley>>

[bystander]

Longest Sunset

• What is the longest possible sunset you can experience while driving,
  assuming we are obeying the speed limit and driving on paved roads? — Michael Berg

[bystander]

Train Loop

• Could a high-speed train run through a vertical loop, like a rollercoaster,
  with the passengers staying comfortable? — Gero Walter

[neufer]

[b][color=#0000FF][size=150]Allo “Dare Devil” Diavolo[/size][/color][/b]

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[b][color=#0000FF][size=150]Diavolo performing his bicycle daredevil act (1905)[/size][/color][/b]

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http://clickamericana.com/eras/1900s/bi ... -1902-1905
https://flightline.highline.edu/iglozma ... iavolo.htm

Click to play embedded YouTube video.

[bystander]

High Throw

• How high can a human throw something? — Irish Dave on the Isle of Man

[neufer]

Click to play embedded YouTube video.

<<The 13 inch (33 cm) Aerobie Pro was used to set the Guinness World Record two times for the "longest throw of an object without any velocity-aiding feature". The Aerobie's first Guinness World Record was set by Scott Zimmerman at 1,257 feet (383.1 meters) in 1986 at Fort Funston, San Francisco. The 1986 record was broken by Erin Hemmings with a throw of 1,333 feet (406.3 meters) on July 14, 2003 at Fort Funston. Hemmings' Aerobie was airborne for 30 seconds (not an official measurement) and was the first thrown object to break the quarter-mile barrier (or 1,320 feet).

On June 7, 1988, the Aerobie became the first object to be thrown across Niagara Falls with a throw by Scott Zimmerman. In April 1987, Zimmerman threw a silver dollar taped to an Aerobie across the Potomac River. Since the introduction of the Aerobie, Superflight has offered reward money for various landmark throws. While details of the earlier rewards are unclear, the current reward is $1,000 to anyone who sets the Guinness World Distance Record.>>

[Ann]

Java Man. Javelin Man. Java man.

Ann

[bystander]

ISS Music Video

• Is this the most expensive music video ever? — Various Youtube commenters

[bystander]

Bowling Ball

• I've been told that if the Earth were shrunk down to the size of a bowling ball, it would be smoother than said bowling ball.
  My question is, what would a bowling ball look like if it were blown up to the size of the Earth? — Seth C.

[neufer]

Click to play embedded YouTube video.

Bowling Ball

<<The holes would be far too big to hold themselves open against gravity; On that scale, the polymers in the bowling ball would behave more like a liquid. In the space of about half an hour, the holes would undergo a slow-motion collapse. As they collapsed, the material around the holes would heat to a glow. At the center of the hole, a white-hot jet of charred hydrocarbons would fountain outward into space. When it was over, Lebowski would be left with massive scars, each marking the location where an abyss collapsed to form a molten sea.>>

[bystander]

Alien Astronomers

• Let's assume there's life on the the nearest habitable exoplanet and that they have technology comparable to ours.
  If they looked at our star right now, what would they see? — Chuck H.

[MargaritaMc]

http://what-if.xkcd.com/47/
So in the end, the clearest signal from Earth might not be from us at all. It might be from the algae that have been terraforming the planet—and altering the signals we send into space—for billions of years.

I first discovered blue-green algae on page 55 of “LIFE, an Unauthorised Biography”, written by palaeontologist Richard Fortey.

Fortey writes that, some three and a half billion years ago: “...the bacterium that was to influence the whole history of our planet used light to break down gaseous carbon dioxide... carbon for its own nourishment and growth, and oxygen. The oxygen was released into the atmosphere as a by-product, the most precious waste in the firmament.” Fortey continues, “I should reiterate that time – 3,500 million years ago – in order to try to come to terms with its immensity. First, imagine each cell exhaling the merest puff of oxygen, such as would fill a balloon smaller than a pin head. [...] each time they divide another minute puff of oxygen is given to the air.”

The tale as told by this marvellous story-teller is heroic. “And now the environment attempted to remove the oxygen as fast as it was formed, for natural materials love such a reactive elements. Limestone rocks captured oxygen in the form of calcium carbonate. Minerals oxidized, in the process gobbling oxygen into iron ores or rust. [...] And against this continuous haemorrhaging only the bacteria – the miniscule bacteria a few thousandths of a millimetre across – puffed and puffed their tiny draughts of breath into the world.”

(R. Fortey. Life: An Unauthorised Biography. A Natural History of The First Four Thousand Million Years of Life on Earth. Published by HarperCollins, London, 1997.) From my blog

Margarita

[MargaritaMc]

Alien Astronomers

• Let's assume there's life on the the nearest habitable exoplanet and that they have technology comparable to ours.
  If they looked at our star right now, what would they see? — Chuck H.

I've just come across this and thought I'd post it here and ask what folk think? Would our heat give us away?
http://astrobiology.com/2013/05/et-dete ... scope.html

Margarita

[neufer]

Alien Astronomers

• Let's assume there's life on the the nearest habitable exoplanet and that they have technology comparable to ours.
  If they looked at our star right now, what would they see? — Chuck H.

I've just come across this and thought I'd post it here and ask what folk think? Would our heat give us away?

http://astrobiology.com/2013/05/et-dete ... scope.html

Thermal Radiation from Gas Giant Planets Summary Info:

• Jupiter: radiates 1.5 - 2 times the energy it receives from the Sun. Excess left over from formation (cooling cake model).
  
  Saturn: radiates 2-3 times the energy it receives from the Sun. Excess comes from frictional heating from raining liquid helium.
  
  Neptune: radiates 2.6 times the energy it receives from the Sun. Excess comes either from frictional heating from raining diamonds or from gravitational contraction of debris absorbed by Neptune in the early days of the solar system.
  
  Uranus: radiates 1.06 times the energy it receives from the Sun. Excess left from formation.

<<In the 1960s, astronomers started observing the sky through infrared sensitive instruments. This new color of light gave us a completely new perspective on our solar system, and on the gas giant planets in particular. In general, when we look at the planets at night with our eyes, much of the light we're seeing is just reflected Sunlight. In the infrared, however, the situation is a bit different. In these wavelengths, which are emitted by any warm body, the gas giants actually emit more light than they receive! With Jupiter, you can "see" radio emission using a simple radio detector.

The sources of this infrared radiation vary from world to world. We see evidence of: leftover heat from planetary formation, heat from gravitational contraction, and frictional heating from different forms of "rain". On Jupiter, the left over heat seems to originate in the planet's formation. When Jupiter formed, it formed hot, and just like a large cake cooling on a shelf, this large planet is going to take a long time to cool off. Saturn is much smaller than Jupiter, but strangely it has even more excess heat than Jupiter does. As a smaller and more distant planet, it should have less excess heat if the only source of the heat is the planet's formation. It's thought Saturn's excess heat may come from liquid helium forming in Saturn's outer atmosphere and raining down through the different layers of the atmosphere. As the helium rain falls, picking up kinetic energy as gravity pulls it through the atmosphere, it may interact with hydrogen at lower levels. These frictional / collisional interactions produce Saturn's excess energy. The situation on Neptune is a bit more complicated. Two different situations are possible: either Neptune suffered a great many collisions with comets and other debris early in its life or it is actually raining diamonds on Neptune. In the first scenario, these materials that Neptune absorbed are currently undergoing gravitational contraction and has these former comets comprise, they're radiating heat. Alternatively, according to work done by Raymond Jeanloz and Laura Benedetti, liquid methane in Neptune's atmosphere may be condensing into diamonds, or at least diamond dust, and as this material falls through Neptune's atmosphere it is causing frictional heating much like the liquid helium on Saturn. Interestingly, Uranus doesn't appear to have significant excess heat. This difference in excess heat between Uranus and Neptune may be behind the differences in appearance between these two planets.

While not a primary mechanism for generating excess heat, gravitational contraction of these gaseous bodies also plays a role. As the giant planets formed, gravity caused them to contract, and it's still causing them to contract (although to a much lesser degree). A shrinking planet has decreasing gravitational potential energy, and the process of contraction converts it into heat energy. Any gas that is compressed will heat up.>>

[Ann]

As you just pointed out, Art, several planets in our solar system give off more heat than they receive from the Sun. The fact that Neptune is "steaming", while Uranus is not, hardly proves that Neptune is home to biological life while Uranus is not.

I feel wary about asking people their very amateur opinion on subjects that they don't necessarily understand very well, particularly if we ask them to vote on the veracity of scientific speculation.

A year ago a rather sensationalist Swedish tabloid asked its readers to vote whether or not there is life on Mars. The answer from the readers was, unsurprisingly, a resounding "Yes!". The readers may very well be right, but a large majority of them probably know little about Mars and so aren't qualified to "vote" on the matter.

I have struggled to make students understand what Galileo discovered about the Earth in the solar system - namely, that the Earth orbits the Sun rather than the other way round. Many of my students are totally uninterested in these matters and don't care very much what an orbit is. The only totally amazing solar system fact they have really understood is that the Earth is round. Therefore, when I ask them what astronomical discovery was made by Galileo, they tell me that he discovered that the Earth is round. So if I were to ask my students to "vote" as to whether the Earth orbits the Sun or the Sun orbits the Earth, it is in fact possible that a majority of them might "vote" for the wrong answer. But whether or not they did, the Earth would keep making a circa 940 million kilometer orbit around the Sun in 365 days regardless of the beliefs of a bunch of Swedish students.

Ann

[MargaritaMc]

The Astrobiology article said that
Rather than looking for radio waves, the team suggests searching for the heat signatures of nearby planets, which requires a giant telescope that could detect infrared radiation directly from an exoplanet, thus revealing the presence of a civilization.

"The energy footprint of life and civilization appears as infrared heat radiation," says Kuhn, the project's lead scientist. "A convenient way to describe the strength of this signal is in terms of total stellar power that is incident on the host planet." The technique arises from the fact that a civilization produces power that adds to the heat on a planet, beyond the heat received from its host star. A large enough telescope, idealized for infrared detection, could survey planets orbiting stars within 60 light-years of the Sun to see whether or not they host civilizations.

>>>
The international team thus seeks funding to build a 77-m telescope, which would be constructed from revolutionary thin-mirror slumping and polishing technologies developed by the Innovative Optics* team.

NB. *Innovative Optics Ltd, who are telescope manufacturers.

So, Art, are you suggesting that this venture would be a waste of time and money

Margarita

[geckzilla]

Maybe if you knew with certainty the planet was small and rocky and otherwise incapable of producing its own heat... or would the heat reading change gradually as the planet revolves indicating localized areas of uneven heating whereas with a gas giant it would remain constant? But then it seems like it could easily be volcanic heat.

[Chris Peterson]

So, Art, are you suggesting that this venture would be a waste of time and money :?: :!:

I'd make that argument (except... it's likely that a large IR telescope could produce a wealth of other valuable information).

The amount of heat the Earth radiates is exquisitely sensitive to the details of our atmosphere. Our planet is heating up now because human activity is changing the atmosphere. But that same change can (and has) occurred naturally. And whether anthropogenic or natural, the heating totally swamps the heat actually produced by human activity. So the question comes down to how well the exact constituents of the atmosphere can be determined... and if you can do that, you have much more information about life than a simple thermal signature provides.

Statistically, we'd expect most planets with life to have something simple, like algae. Very few would have technological life, and of those, most would be far more advanced than us, meaning they'd be managing their waste heat and climate very effectively (as I'd expect us to do inside a few centuries at the most, assuming we remain technological).

[MargaritaMc]

http://the-colossus.com/bigq.html
This is the project's website, but there just is not the kind of detailed information that I would expect for a project of this magnitude. There is an article in the current issue of 'Astronomy' magazine, but I haven't seen anything about it elsewhere.I read about it in an email newsletter I get from 'Astronomy'. It just seems well, a little puzzling that the info is so thin, especially as they must be seeking gadzillions of bucks to build the Colossus.
Margarita

[geckzilla]

Reading the website, it does seem kind of like a gimmick to try to get funding. Hey guys, we're going to find some aliens! Give us money. Five years later: well, we aren't sure they are aliens but we did find a lot of interesting stuff.

[MargaritaMc]

Reading the website, it does seem kind of like a gimmick to try to get funding. Hey guys, we're going to find some aliens! Give us money. Five years later: well, we aren't sure they are aliens but we did find a lot of interesting stuff.

Did you read the Astronomy magazine article, available as a download from that site? On the basis of what I read in that, I wouldn't invest £5.00!

I just have Macbethian Witch's sense in my thumbs...


Margarita