Monkees Daily Nightly

I just found this song, Daily Nightly by the Monkees.  It's probably not that great but it really made an impression on me because it used a Moog synthesizer.  On-line articles say this was the first pop song to use a Moog and that Dolenz was the third artist to own a Moog.

World Clock

This is an excellent GUI World Clock.

Best Space Probe Photographers of the Decade

The images in this Discovery Space article, Best Space Probe Photographers of the Decade, are amazing and fresh!  They are different from the images we see the most.

Web Sockets and Tornado

Maybe you've never heard of web sockets.  Here's a brief introduction to web sockets which are implemented in Tornado.

Web 3.0

This is an interesting and somewhat useful article about Web 3.0.  It describes what many would agree the elusive Web 2.0 term means.  (If you feel like you've never been completely sure exactly what Web 2.0 means, you're not alone.  It's an ill-defined term).

This article probably falls short, though, on it's predictions.  I'd say almost the majority of what it predicts is already here in some form, not something out in the future.

Google Maps Navigation Works Without Signal

Over Christmas weekend I had the opportunity to use Google Maps Navigation on Android 2.x.  I confirmed that Navigation works when you don't have signal.  I'd heard that it caches enough of maps that it can idle without Internet access for a while.  Of course GPS is still working during that time.

More than 10 miles of the last leg of my trip were without any cell phone access at all, no phone network, no Internet data access.  Navigation worked flawlessly right up to the last turn into the destination driveway including the maps, turn by turn voice navigation, etc., etc.

Russia Plans to Save Earth

Russia Plans to Save Earth From Rogue Asteroid. My favorite line is “everything would be done ‘on the basis of the laws of physics.’”

I'm fascinated by the possibility of violating the laws of physics.  If they can do that then I say, Don't apologize! Carry on!  There are probably much more interesting solutions in that arena!

Also interesting is the “no nuclear explosions” policy.  I understand a concern about a nuclear power building large bombs and mounting them on rocket boosters and putting them in spacecraft.  Still, it's the most efficient case of energy per mass.  It's the best way to get the energy needed to change the momentum of an asteroid to the target.  If you are really saving the earth (an important requirement) then I think it's definitely time to drop the pretense of political correctness.

Facebook Privacy

Summary

On Facebook, check Settings, Privacy Settings, Applications and Websites, What friends can share about you.  Then click on Edit Settings.  You probably want them all set to friends only.

Run applications with care.  The popular ones are probably okay, but beware of new and unfamiliar applications

Details

The news articles about Facebook privacy finally got my attention so I decided to finally check out what's going on there.

The most important thing is to go to the Privacy Page and check out the settings there.  Even after you check the little “simplified” page that the special announcement on Facebook shows you, it's still important to go the Privacy Page and check all of the settings.

Follow the menus (starting at the top right of the screen):   Settings > Privacy Settings.

There's no immediate danger involved in any of these.  It's all about how much you want to share.  I generally restrict just about everything to just Friends.

The one I'd pay careful attention to is Settings > Privacy Settings > Applications and Websites > What friends can share about you.  Then click on Edit Settings.

Just to be clear about what this means, when you use something like Something-ville, or My Family, etc., those are applications.  They are written by, well by anyone (you could write youself), and when you join/use them, you basically give them access to your Facebook account.

I believe that up to now, such applications had access to all of your information and they could do with it what they wanted to.  I don't think anyone has a reason not to trust some of the more popular apps that are on Facebook.  LOTS of people are using them and I've not heard of any problems.  Still, it's a good idea to be cautious and not just grab onto any application that pops up.

A major part of this recent change is to let you limit how much of your information such applications can  share with anyone.

Some folks may have noticed that I don't use (knock on wood) any applications at all on Facebook.  I'm not at all saying that everyone should avoid them.  In my case I'm not ready to put time into them.  Still, though, I also don't know who they are from, how trustworthy they are, and haven't taken the time to figure all of those details out.

With these new settings (that I've restricted to all friends access, only) I'd feel safer in actually using one of the apps.

As a final thought, I'd be careful about the Friends of friends setting.  As I understand it, that means not just your immediate friends can see something, but their friends as well can see it.  Most of the time, that's probably okay, but if I learned anything from MySpace, it's that only two hops away from someone you know are some pretty seedy people.  It's sad I know.   On the other hand, most people you've ever heard of are probably only two hops away, maybe three, at least as far as acquaintance goes.  If you believe, Kevin Bacon, six hops cover everyone in the world.*

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* Via Google, I find the population of the world for 2008 is 6,692,030,277.  We want to know what x is for x⁶ = 6,692,030,277.

log x⁶ = log (6692030277.00) = 22.62


6 log x = 22.62
log x = 22.62 / 6 = 3.77
x = exp(3.77) = 43.41

I think this means that, if everyone knew 43.41 different people, with no overlap, then Kevin's six degrees would work.

Cosmological Distance and Grains of Salt

Why do I always say to take large distances in space, say to galaxies in a Hubble deep field image, with a grain of salt?  The main reason is that, in an expanding cosmology, the meaning of distance is not a simple concept.

In the diagram we represent space with the horizontal s-axis and time with the vertical t-axis.  There are two galaxies and both are stationary in the space around them.  However, because space (s) is expanding, B is getting farther from A, not because B or A is moving, but because the space is expanding.

At the point in space and time, B, a photon of light leaves that galaxy and travels to our galaxy where it arrives at A', later in time.  The red path represents the path the photon takes through spacetime.

The red path of the photon is curved which is a consequence of the expansion of space as it travels.

How far away?

Now, everyone wants to ask the question (when we at A' look at our picture of B), how far away is B?  Well, there are at least three distances here.  There's the distance AB, there's the distance A'B' and there's the path the light actually took BA'.  When someone says the distance is 13 billion light years, which one of these are they talking about?  If your answer is that you don't know, well, I don't know either.

The problem is actually worse than this.  In my diagram, I've represented space as expanding at a uniform rate.  That rate would be represented by the slope of the BB' line.  However, space doesn't really expand at a uniform rate but at a changing rate.  Worse, it's lately come to light that the rate is increasing, i.e., the expansion seems to be accelerating.  So, the BB' line wouldn't even be  a straight line in this diagram.  The BA' photon path would be different.

A tale of two numbers

In fact, how you draw this diagram in detail depends on the cosmological model of how space expands with time.  You can write it down as a simple function of scale and time, R(t).  However, we don't really know well what the current rate  d R(t) / dt  is, or even the acceleration d² R(t) / dt² is.  By the way, the rate is called the Hubble constant.  (Of course, if there's acceleration, then that speed isn't a constant).

What do we know?

There is really only one thing we know with high accuracy from these observations.  The wavelength of light when emitted at B was proportional to the length AB.  The wavelength of light received at A' is proportional to the length A'B'.  So the ratio of A'B' / AB is equal to the ratio of the wavelengths.

The redshift is expressed as a value called z.  If the new wavelength is three times the original length (i.e., the ratio is 3), astronomers say the redshift z = 2.  That's because you add two more of those wavelengths to the one you started with to get 3, or you shifted it by the amount 2.

So the one thing we know is that scale of the universe (the distance between distant galaxies that are sitting still) is z + 1 times bigger than when the light was emitted.

That's why I'd rather just hear the redshift for these observations and leave the other details to be figured out some day.

How far have we seen?

Some recent record observations of redshift are around z = 7, so we've seen some objects as they were when the scale of the universe was 1/8 it's current scale.

Of course this is also model-dependent, based on the concepts of cosmological redshift and general relativity!

__________
I think the phrase “a tale of two numbers” should be attributed to Edward R. Harrison, probably from his book Cosmology:  The Science of the Universe.

Digital Archives and File Corruption

From Slashdot.

“…massive digital archives are threatened by simple bit errors that can render whole files useless. The article notes that analog pictures and film can degrade and still be usable; why can't the same be true of digital files?”

TWIG

I've become completely addicted to This Week in Google (Twig) on Twit.tv.  The show is hosted by Leo Laporte and usually features regulars Gina Trapani and Jeff Jarvis.  Recommended!  I actually learn new things from this show every week.

You can listen to the podcast and/or download the MP3 and even burn it to CDs like I do, to play in my car.

The show is recorded on Saturday evening at 17:15 ET, roughly, so you can watch the live video stream on the web page.

Pournelle on TWIT

I may not even have posted here how I've gotten addicted to Twit.tv.  This week, one of my favorite authors, Jerry Pournelle, appears on TWIT. (This Week in Technology, a web-based radio program hosted by Leo Laporte).   I've only listened to the first bit of it, but I recommend listening to the podcast (which is also a downloadable MP3).

Safe Computing!

This is an excellent blog post by Sarah Perez regarding malware getting on your computer when you click on short URLs on Twitter and Facebook pages.  The advice in the article is good so I won't repeat it here.

I'll just add these bits.

• Use Chrome as your browser.  If you don't use Chrome, use Firefox.
• Use Ubuntu or Mac OS X if you can.
• If you have to use Windows, it's imperative to keep it up to date and use virus software.  AVG and Avast are good choices.