About Me

My photo
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.

Friday, January 21, 2011

Dark Matter or, "we're pretty sure it's there"

First off, i'd like to thank everyone reading this page for their encouraging comments, I just hit 50 followers recently and I hope that the information I try to break apart here is of some use to you. If it's not, or if you interests lie in a different direction please let me know! I am always open to talking about specific topics of interest, if there is anything you feel you would like me to elaborate on or attempt to convey in an understandable manner just leave me a comment and ill do my best to accomodate.

Second, Comcast sucks, I don't know about the rest of you but I have always had problems with them trying to stayconnected when I need to, otherwise this would have gone up much earlier today.

Today I want to talk a little more about this stuff that scientists have dubbed "dark matter" and I think the best place to start is why we would even think it's there in the first place. I mentioned last time about how astronomers use gravity to notice something that should be there when you can't detect it normalls, but the manner in which they do that is much more refined. Over extremely great distances everything is affected by gravity, even light,  so one of the primary methods for detecting this dark matter is known as "gravitational lensing". When light from a very bright object in the sky (even brighter than most individual galaxies we are talking about exploding stars and large clusters of galaxies here) is distorted (or bent or however you want to say it) into arcs or curves then it's possible to measure the angle of this distortion and find out how large this invisible object is (or at least it's mass, which doesnt really tell us alot about it's physical size. You can see an example of lensing below.

There are a few other methods for detecting the presence of dark matter in the sky, including looking at the data provided for the CMBR (see earlier post) however let's talk about what we actually know about this stuff, this matter that we can't see. Most of the information about what dark matter is actually composed of is speculative (or nobody really knows but it's fun to make stuff up) and most of them revolve around large mass objects that we wouldn't be able to see normally: black holes, small faint stars, and some kinds of gas are all thought to be contributors.

Some have postulated that there are at least three forms of dark matter, cold warm and hot, however these terms deal more with their speeds than their temperature. Cold dark matter is the stuff that travels at speed we are used to, known as "classical" speeds. Warm moves at nearly the speed of light and so faces interaction with the doppler effect mentioned in an earlier post. Hot dark matter is thought to move at speeds extremely close to the speed of light, so close most people would just round up. The cold dark matter represents the greatest interest to modern scientists because of it's relatively "slow" speeds it would be a large factor in how galxies and their clusters were formed towards the beginning of the universe.

In any case attemting to directly detect dark matter is pretty frustrating. Most use one or two technologies to detect this stuff, and have to be situated deep within the earth to protect it from interference from all of the other radiation raining down on our planet at any given moment. One popular method is a detector so cold it reaches down near something dubbed "absoulte zero" if we are talking about celcius it's around -273, and detect the slight variation in temperatures. Needless to say keeping a detector that cold all the time is pretty expensive.

To summarize, dark matter is simply a term that reflects the modern scientific world's ignorance of what nearly 25% of all the detectable material in the universe is composed of. Detectable only through indirect methods, it will be some time before our techniques are advanced enough to really understand what's going on out there.

Next time I think we will go into the speed of light and why it's so important that nothing can ever pass it (think of it like a universal speed limit).

45 comments:

  1. science is constantly changing, who knows what we will think in 30 years, looking back being all pfft they thought dark matter was a thing, who knows right :P

    http://entertainvent.blogspot.com/

    ReplyDelete
  2. Really interesting post. I took an introductory Astronomy course this year, and it's fascinating how little astronomers actually know about what the heck is going on in the universe. They're sort of like the crazy people of the scientific world.

    Followed. Can't wait to see your post about the speed of light.

    http://autotunedsoul.blogspot.com/

    ReplyDelete
  3. Its crazy how we still don't know the composition of 1/3 of the matter in our universe.



    http://dubstep-newdubstep.blogspot.com/

    ReplyDelete
  4. brilliant post, following with passion.

    sSp3ct.blogspot.com

    ReplyDelete
  5. Agree with ya on comcast sucking ha

    http://asfarastheyletme.blogspot.com/

    ReplyDelete
  6. Very interesting blog...I've always had a liking towards astronomy and whatnot....pretty good start for me here.

    Gotcha back :)

    ReplyDelete
  7. So... are you saying if we go past the speed of light, it would be as if one divided by zero? hmm? >:3

    ReplyDelete
  8. Great post and thank you very much for following me! Certainly doing the same - keep up the great work.

    howtohackyourlife.blogspot.com

    ReplyDelete
  9. I'm happy to live in an area which isn't monopolized by Comcast with all the horrible things I've heard from them.

    ReplyDelete
  10. Nice post dude, defo going to follow!

    ReplyDelete
  11. Wow, absolutely fascinating blog you've got here. Learned a little about dark matter in my astronomy class last semester but we didn't really go in detail about it.

    Following!

    ReplyDelete
  12. Dark matter has always fascinated me. Things like this make me wish I would live another 200 years just to see if scientists can prove it's existence.

    ReplyDelete
  13. there's still so much things to discover and only with time and the advancement of technology and techniques will we be able to study it further.

    ReplyDelete
  14. Oh man I love space and this type of stuff

    ReplyDelete
  15. i wish to see the revealing of dark matter before i die. i hope they can find more about it soon

    ReplyDelete
  16. Great article, and an even better job on bringing science to the masses

    ReplyDelete
  17. i have trouble staying connected with comcast too :( brb restarting internet almost everyday

    your friend,
    http://ectomorphmuscle.blogspot.com/

    ReplyDelete
  18. intresting post dude
    supported/following

    hit me back
    http://xxtols.blogspot.com/

    ReplyDelete
  19. I agree about comcast haha but on a serious note dark matter has always been interesting to me. Its just a really strange concept that is fairly complex to understand.

    http://ducks2nucks.blogspot.com/

    ReplyDelete
  20. dark matter sounds awesome, I wonder if someone could get it, he'd be rich as hell, that's for sure :P

    velimas.blogspot.com

    ReplyDelete
  21. A very interesting post. Still waiting for the day we find out what dark matter is. I hope I live that long.

    ReplyDelete
  22. i guess i didn't post the comment i meant to post yesterday...either way.

    followed n such.

    ReplyDelete
  23. awesome blog man. science rocks. followed. swing by my blog and see if you find anything interesting. make sure to let me know when you update thru a comment

    ReplyDelete
  24. dude, you definitely have one of the most interesting blogs I follow. Keep it up man.

    ReplyDelete
  25. Nice post! following and supporting :D

    ReplyDelete
  26. cool post! What are the methods to indirectly detect the different kinds of dark matter? I'm curious.

    Following.

    ReplyDelete
  27. Enjoy reading your blog bro!

    Comment back!

    http://mrangrie.blogspot.com/

    ReplyDelete
  28. fucking space how does it work?

    http://extremespooks.blogspot.com

    ReplyDelete
  29. follower 90~ 10 more til you have 100! :)

    This is one of few blogs that I've found that are actually interesting. I'll have to read the rest of the posts when I have time.

    ReplyDelete
  30. great post!!! i am following.

    www.skatescene69.blogspot.com

    ReplyDelete
  31. Interesting. I've heard of dark matter, but I wasn't sure if it actually existed. Guess I learned something today lol!

    http://lunch-timeconversations.blogspot.com/

    ReplyDelete
  32. interesting

    Im looking forward to you next post because the speed of light is also the topic in our physics class. maybe you post can help me :-)

    ReplyDelete
  33. Like entertainvent said, science is constantly changing :D

    ReplyDelete
  34. nice blog!

    follow me back at:
    http://all-around-toto.blogspot.com/

    ReplyDelete
  35. I've never been sure if I bought into dark matter thing. Nice article.

    ReplyDelete
  36. WOw this is too complex for me to comprehend. Check out my blog at: alphabetalife.blogspot.com

    ReplyDelete