Happy Fourth of July!!

[RStar]

Originally Posted by Alex

And kids will lie down in the cereal aisle and throw a fit if you deny them their preferred sugary cereal.

But sometimes you have to be the adult and hold firmly to "no." It's for their own good Kevy.

***SNORT***

Sorry

Originally Posted by JWBear

The people who live a few houses down from the party I was at last night accidentally lit some of their front yard shrubbery on fire with fireworks (at least, I'm assuming it was an accident). Is it wrong of me to have found it hysterical?

No, not at all. I've been lighting off fireworks for 40 years, and I have never lit anything on fire, nor hurt myself or anyone else. Only stupidity can do that, and stupidity must be laughed at or all is lost!

Originally Posted by Alex

The Tifft research (with Arp's follow up) that you're quoting

Shoot! I was hoping I'd at least get a few posts about how intelegent I sounded before I posted the sorce of my quote.

Oh well, everyone knows better anyway!

That was not the link, Alex. This is: Red Shift Riddles

[Alex]

RStar, that page is a subpage from the one I posted above. Remove the redshift.html part of the URL and you'll get it.

It is a page or fundamentalist Christian theories of science. Needless (I hope) to say, most of them aren't very strong arguments (and most aren't even accurate representations of the science).

[blueerica]

I stopped by the grocery store before I hit the highway yesterday, and PTBAA came over the speakers. I chuckled to myself and thought I hope Alex was just kidding about the carpet bombing... I just wanted to get some crackers.

[cirquelover]

We went and bought fireworks at half price today. I love a bargain! Now when Gary gets home we can light a few with him too.

[Not Afraid]

Yeah, that was one really great holiday.

[innerSpaceman]

Hmmm, sorta gives a second meaning to "Independence" Day though.

[BarTopDancer]

Nothing says Happy Birthday America like blowing stuff up.

[RStar]

Originally Posted by Alex

RStar, that page is a subpage from the one I posted above. Remove the redshift.html part of the URL and you'll get it.

Oh, thanks Alex. That's the problem with Google-type searches, sometimes you just get the one page. I hadn't thought of going to the main page by dropping the extentions on the address. Great trick.

I hadn't even heard of Red Shift before this thread anyway. Interesting idea, I'll have to find some stronger, more accurate info on the subject.

[Alex]

You've probably heard of it as the Doppler Effect. Essentially, when something is moving away from you the wavelength of light from that object is "stretched" which has the appearance of being more red than it naturally is.

In reverse, an object moving towards you shortens the wavelength making it look more blue. This is blue shift.

For cosmology, if you have a method for knowing what the natural wavelength of light is (and spectroscopic measurements give us that for stars) you can then determine the relative motion between you and that object. Since, when you look out into space, pretty much everything is red shifted that suggests everything is moving away from everything else. And because the red shift is proportional to the distance away from us (things farther away are moving away faster, aka Hubble's Law) that is strong support for the idea that space itself is expanding and is a key underpinning of the Big Bang.

On a much more local level, redshift/blueshift (oneshift, twoshift), is used for many things. One example would be police radar guns. The gun emits light of a known wavelength which hits the target and reflects back to the gun. If that object is moving relative to the speed gun the wavelength of the light will be subtly changed during the reflection. If it is more "red" then the object is moving away; more "blue" and it is moving closer and the amount of change tells you how fast.

Another local use is in the Doppler Weather Radar all our TV stations brag about having. The key different between previous weather radar and the suddenly hip Doppler radar was that it added the ability to measure phase shift and so could "see" wind rather than having to physically measure it on site. So not only could the weather station say "it is raining over there" but also "it is raining over there and moving towards over here at some miles per hour." Even more valuable is that it has allowed for much improved tornado prediction.

Thus ends today science lecture. Please fill out the comment cards before leaving as that is how they decide if I get tenure. I'm sure someone will be along to correct my mistakes if I made any.

[mousepod]

Nicely summarized, Alex. Thanks.