Author Topic: Just out of curiosity... (Read 2974 times)

GRUNHERZ · « **Reply #90 on:** June 05, 2003, 05:12:48 PM »

Evolution is a proven fact Hortlund. And we acn observe it every day in fact. Why do you think bacteria become immune to antibiotics over time? The ones who are not killed by the anti-biotic routine pass on their resistance to future generations, thats EXACTLY how evolution works and its visible every day.

Wlfgng · « **Reply #91 on:** June 05, 2003, 05:17:59 PM »

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back to one of the basic laws of physics (i think thats it) "Matter can not be created or destroyed"
no if that being the case a BB cant create matter nor destroy it.

and now Hawking's version:

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Because matter and antimatter annihilate one another in a burst of electromagnetic radiation (energy in the form of particles called photons, visible light is a kind of electromagnetic radiation) the universe we see today is dominated by the extra matter that couldn’t find antimatter with which to

Syzygyone · « **Reply #92 on:** June 05, 2003, 05:19:20 PM »

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Originally posted by midnight Target
Watched a show recently about the quest to determine the mass of the stuff in the universe. This is critical if you want to determine whether its gonna keep expanding, or if it goes through a never ending series of expansions and contractions.

If enough stuff is found... then our future is pretty bleak. Eventually the sky will grow brighter than day with millions of stars. Life will be snuffed out by the heat not long before the Earth itself becomes a cinder.

If not enough stuff is found.... our future is pretty bleak. The sky will grow progressively darker until no stars are visible at all. We will be more alone than you can imagine before our sun burns out and all is blackness.

Have a nice day.

Well, someone as old as you doesn't need to worry too much about the future anway. So Yes,have a nice day!

Wlfgng · « **Reply #93 on:** June 05, 2003, 05:32:04 PM »

so then..

kling-offs?

GrimCO · « **Reply #94 on:** June 06, 2003, 07:40:57 AM »

Thanks for all your responses guys...

I thought I was the only geek that thought about such things...

But seriously, I appreciated all the responses and viewpoints!

GRUNHERZ · « **Reply #95 on:** June 06, 2003, 08:38:59 AM »

"Originally posted by boxboy28
back to one of the basic laws of physics (i think thats it)
"Matter can not be created or destroyed"
no if that being the case a BB cant create matter nor destroy it.

back to the question at hand .........it has always been and will allways be. We humans created time and feel everything must start and end!

My question is if they can tell the universe is expanding....can they see the end of it? how can they tell its expanding"

Doppler effect - like when a car drives towards you and then away - the sound you hear changes because the sound weaves are getting compressed as the car comes towards you and are expanding when it is moving away from you. The same thing works with airplanes, thats why flybys by prop planes sound so cool and change pitch as the planes moves towards and awar from us.

The principle also applies to light. Hubble discovered in the 1920s/30s that distant objects were getting farther away from the earth because the light they emmited was shifing to red color which meant they were moving away as opposed to blue which would happend if they were getting closer.

AKIron · « **Reply #96 on:** June 06, 2003, 11:01:03 AM »

I'm trying to understand this whole concept regarding the expansion of the universe. If a doppler shift measurement is being used to determine whether or not the universe is expanding then it must be possible to determine the center from which the universe is expanding.

Only one semester of college physics here so bear with me (did get an A tho). Assuming we can determine our distance to the stars we are measuring then those stars moving away from us must be farther from the origininating point of the universe and moving faster than us as indicated by the doppler shift. We should then find that in an opposite direction that we are moving faster than those stars still closer to the center than us but moving in the same direction.

The greatest shift should be observed in those most distant stars observable in the same relative direction as those slower stars closer to us and on the same side of the center. Those most distant stars would be on the other side of the center and moving away from us.

If I have the gist of it then why is there so much doubt as to whether the universe is expanding or contracting?

Sandman · « **Reply #97 on:** June 06, 2003, 11:09:09 AM »

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Originally posted by AKIron
If I have the gist of it then why is there so much doubt as to whether the universe is expanding or contracting?

Not according to the last Cosmology class I took... It's expanding without question.

GrimCO · « **Reply #98 on:** June 06, 2003, 01:16:38 PM »

There's really no doubt the Universe is expanding. The question is will it keep expanding or eventually stop and contract.

As far as there being a "center" to the Universe, it really doesn't have a defined center...

Imagine a rubber sheet. Place dots on the rubber sheet representing each cluster of galaxies in space. Now stretch the rubber sheet from all directions (all sides and corners). Each dot will move farther away from the next as you continue to stretch the sheet, but not from a defined center point.

This is of course a simple 2 dimensional example. In three dimensions the galaxies would move away from eachother on all three axis of space.

Individual stars in individual galaxies are not moving away from eachother because they are gravitationally bound together by the galaxy in which they are contained. Also, galaxies in the same local cluster are not moving away from eachother either because they are bound by eachother's gravity. It's entire clusters of glaxies that are expanding away from other clusters where the huge distances between them make their gravitational influence on eachother negligable.

AKIron · « **Reply #99 on:** June 06, 2003, 01:25:41 PM »

By center I mean the point (if indeed there was a bb) from which it began expanding. And if we can see far enough to see beyond this point, we should be able to determine where it is/was. Assuming that matter expanded from it in the general shape of a sphere.

GrimCO · « **Reply #100 on:** June 06, 2003, 01:33:31 PM »

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Originally posted by AKIron
By center I mean the point (if indeed there was a bb) from which it began expanding. And if we can see far enough to see beyond this point, we should be able to determine where it is/was. Assuming that matter expanded from it in the general shape of a sphere.

Shape of the Universe

GrimCO · « **Reply #101 on:** June 06, 2003, 01:42:52 PM »

Each object you see in this image taken by the Hubble telescope is an individual galaxy, not a star. Even the little dots are galaxies. This picture comprises about a one quarter of an inch field of view of the sky.

There's a lot of galaxies out there boys... with about 300 billion stars in each of them.

I don't know about you, but to me it's just absolutely mind boggling...

AKIron · « **Reply #102 on:** June 06, 2003, 01:55:14 PM »

Definitely a mind boggler.

Holden McGroin · « **Reply #103 on:** June 06, 2003, 02:09:57 PM »

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Originally posted by AKIron
By center I mean the point (if indeed there was a bb) from which it began expanding. And if we can see far enough to see beyond this point, we should be able to determine where it is/was. Assuming that matter expanded from it in the general shape of a sphere.

Everywhere is the center. Just as everywhere on the surface of the earth is the center of that two dimensional surface, curved in a third dimension, everywhere in the universe is the center of that three dimensional volume, curved in a fourth.

At the moment of the big bang, all the universe was inside that small point, even the empty space. So in a sense, the clerics who imprisoned Galileo were right, the earth is the center of the universe. Of course, so is everywhere else.

AKIron · « **Reply #104 on:** June 06, 2003, 02:33:34 PM »

Maybe center wasn't the right word to use. Using cartesian coordinates we should be able to determine the point, relative to our current position, from which we have traveled since the big bang.