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I am a low-level teacher with an amateur passion for the advancement of modern society. My specialty is physics but all forms of the advancement of knowledge are something I consider extremely important.

Wednesday, January 19, 2011

Redshift and you, Dopplers' legacy

I have mentioned recently a little about what the CMBR is and why scientists think its so important to understanding the formation of our universe. it's easy to wonder though, just because you can see a relatively uniform (at least in the space between galaxies) wash of microwaves, how does that indicate some kind of formative explosion?

To undertsand that we have to understand something called redshift.

Ever stand near a moving train or car while some sort of horn is blowing and noticed that it was a little higher pitch before it passed you, and lower afterwards? Or perhaps you saw a jet plane pass over you before you heard it, and when you did it was really loud? The reason for this occurence is known as the Doppler effect (I just like to call it Doppler Shift). To undertstand what that is first you have to know a little about how sound works.

Imagine a perfect peaceful pond, and you drop a single stone into it such as the picture above. It creates ripples that move outwards, the same thing happens every time you hear a sound. From the tapping of your fingers on a keyboard, to merely the sound of your voice all sound ripple outwards like that.

Now, we call those ripples waves, and they only stay circular like that as long as nothing is moving. In the case of a moving car or train, or even if you are talking to someone while walking these sound waves can "bend" a little. Right in front of the car or train or whatever is making noise these waves can "bunch up" and get compressed, because of this you hear it at a higher pitch than normal. And behind the source of this noise the waves get "stretched out" and you hear them at a lower pitch. This happens more and more as you approach the speed of whatever it is we are talking about (in this case the speed of sound).

Anyway, thats the idea behind doppler shift, in case you were wondering where I was going with this, many different things are expressed as these waves not just sound. Earthquakes, waves in water, and most importantly light are all different kinds of waves. All that matters is what they move through (sound through air, waves in water, earthquakes in land) however light is special, as of the current day nobody understand exactly what it is that light moves through, or if it has to move through anything at all since it can exist in a perfect vaccuum.

Everything I just mentioned applies to light as well as sound, however light is much less noticable, and it only really matters when you start approaching the speed of light (so very incredibly fast that nothing we have created even comes close, breaking the speed of sound was hard enough). Being able to notice these small distortions in light is the basis of why physicists think the universe was created in a large explosion, or "big bang".

To relate, just like the sound waves bunch up in the direction the car is moving, if you were to take a lightbulb and move it really fast the light waves would bunch up too, and you would see the light as "blueshifted", contrary to that behind the lightbulb you would see light that has been stretched out or "redshifted".

So here is the deal, and kinda the point of this whole thing. When an astronomer analyzes light coming from a star thats really far away, it looks as if it is redshifted, that is the star he is looking at is moving away from us at some speed based on just how red it is. The thing is, no matter what star you are looking at the further away it is the more redshifted it looks. This leads scientists to believe that the universe is expanding in every direction at all times, thus that a large "explosion" was where the universe began.

To summarize stars that are very distant are "redshifted" or moving away quickly. This combined with the CMBR are the basis for the "big bang theory", and its why scientsts tell you they can figure out just how long the universe has been around, because if we know how fast everything is moving away we can figure out how long its been moving like that.

Next time ill wrap up Cosmological Recycling and explain why these scientists may have been mistaken, as always the facts dont neccecarily add up to the conclusions we want to believe.


  1. Very clear exposition. You must be a very good teacher.

    P.S. Captcha (Word verification) is on.

  2. great info man. keep us posted.

    supporting this blog


  3. Very informative, following and supporting! ;)

  4. I remember studying this stuff back when I did natural disasters. Interesting read, it's rare that you see a smart blog, haha.



  5. stuff looks very wild, it will be interesting to read more as it is posted.

  6. Good to see people thinkin on a proper level. Clever.

    Want to step your game up and get WOMEN?

  7. I've always wondered about this was an interesting read thanks!

  8. Wow thanks for that info, you're very intelligent.

    I will continue to check back on this blog everyday as it is very important to understand (or at least try to) the workings of our world.

    Following and supporting.


  9. this is beyond me. no wonder i dropped engineering and went into history...

  10. Very interesting post. Followed

  11. interesting stuff and rewarding to know, thanks for posting <3

  12. Excellent informative presentation of the information.. Thanks

  13. very great info.. supporting for sure!

    clicked & followed... hit me back

  14. interesting information, and thanks for following me; i'll be sure to check your cool blog often :)


  15. Very interesting post, loved it

  16. i live in a bad neighborhood so i experience the Doppler effect all day and night haha. i should move. i had never heard of "redshifting" or "blueshifting" until i read your post today - damn public school system!

  17. Wow... that's pretty intense stuff, thanks for the info!

  18. Not very often you see an intellectual blog. Following.

  19. Nice information. Will definately keep an eye on your blog.

  20. Absolutely mind blowing! Thanks for the great info :)


  21. Subscribing now.


  22. great blog bro! following