Cosmic concepts
- Michio Kaku (Author of Parallel Worlds) [00:03:01]
Truly intriguing. Please buy about 45 minutes of time to watch this:
Channel: History Channel
Programme: The Universe
Synopsis:
Scientists have no idea what it is, but Dark Matter and Dark Energy make up 96% of the Universe. Dark Matter is everywhere. It passes through everything we know on earth at billions of particles every second, yet no one has ever gotten a direct detection of this mysterious dark substance. An even more bewildering force is Dark Energy, which is rapidly pushing apart our Universe. Discovered only ten years ago, scientists are struggling to comprehend its unusual characteristics and answer the ultimate question; what is the fate of our Universe? Using cutting-edge computer graphics watch as the universe is brought down to earth.
well... what say you after watching this?
posted by hweiee at
6:27 PM
3 comments
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3 Comments:
if scientists claim that all galaxies are moving away from each other from every direction they look (with Earth being their vantage point), then they are assuming Earth/Milkway to be the centre of the universe, no?
but that would contradict their theory as, then, the Milkyway would be stationary, and not speeding across the universe. so technically, aren't scientists merely calculating the relative velocities of the galaxies rather than their absolute velocities?
hmm it clicks for me, however.
The Earth doesn't have to be at the centre in order to see that all the other galaxies are moving apart. but in a way, I agree with you that they are all relative measurements.
I'm not sure... not really an avid reader of cosmo- stuff. *shrugs*
that whole dark matter is really overwhelming (if you caught that pun)
actually, i would like to retract my statement. scientists do not require the milkyway to be stationary to determine that other galaxies are moving further and further apart from each other. we have to take into account that as galaxies get further and further from the initial point where the big bang occurred, they gain more and more speed due to dark energy. if you visualise a model in your head, with 3 objects travelling in a straight line, one behind the other and assuming the milkyway is the middle object, both other objects will be seen moving away from the milkyway. the galaxy initially furthest away from the point of origin of the big bang will continue to speed away, travelling faster and faster; hence moving away from the milkyway. the galaxy that was closer to the point of origin of the big bang as compared to the milkway would also be accelerating. however, since the milkway was initially further away from it, the acceleration at which the galaxy travels at is less than the acceleration the milkway travels at. hence even if the milkyway is speeding away from the point of origin of the big bang, other galaxies can be viewed "accelerating" away from the milkway. however, the velocities obtained are all relative to the milkway's velocity.
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