the universe and space....?

Maybe it was a temporal rift in the fabric of space/time

Could be, but I'm not that knowledgeable about science. c.i.

ci, Give it a little more time.
Time as related to the speed of light gets interesting.
If you view time as a constant, then the speed of light varies. If you view the speed of light as constant then the speed of time will vary.
This can get very interesting. There are several sites on the web related to Einsteins Relativity Theories. Try this one to get you started.
http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/gratim/.html
Hope it works, these long addresses seem to confuse either me or Cyclops here. Most probably me.

Mech.., C.I.; didn't work, try going to the "parent directory"
http://hyperphysics.phy-astr.gsu.edu/hbase/relativ
then selecting
gratim/.html (worked for me)

BGW, Thanks. So, in essance, gravity has an influence on light and time? c.i.

Yes C.I.,
Now comes another "question".

Does gravity affect light and time-- OR--

Does gravity affect our perception of light and time?

Nor does it seem too much to ask--

Does our perception of gravity affect our perception of light and time?

OR does our perception of light affect our perceptions of gravity and time?
OR any combination of the above?
Relativity does get deep quickly. Actually it very soon runs into problems with " the nature of reality". Whatever that is.

If we take a definition of reality, then how far can we run with it before we run smack-dab into Relativity?

I am beginning to understand why "God knows" has been a stock answer to ultimate questions over the ages.

But, IMO, we need not be satisfied with that answer.

Now Mech;
This could be the beginning of something really BIG!

Do we perceive gravity (I am aware of the "gravity" of your question, but I mean the actual "pull" of the stars).

I would say yes, and (this is heretical) it probably accounts for the ancients preoccupation with Astrology; I have always contended that within any long standing tradition of belief, in even the most ridiculous of tenets, there must be a grain of reality which originally sparked the gross over reaction, take organized religion (any flavour) for example.

GRAVITY; even the word has immense force don't you think!

Hi Bo, CI et al;
There is indeed gravity and sobriety in my answers on this thread.

Yes and no; We can perceive the effects of gravity without necessarily KNOWING what it is.

A portion of the "red shift" discussed briefly in this thread earlier is an effect of "gravity".

The moon overhead is there as a result of the effects of gravity.

And I would never deny that the position of the planets at the moment of conception (roughly translated into time of birth) may have affected the actions of the chromosomes involved. (but I'll probably never attempt to affirm it either) This would be a mechanical basis for astrology.

And gravity, along with the other natural forces found in Quantum Mechanics has never, to my knowledge been adequetly explained.
We know the force it exerts. We can determine the force at any distance you care to mention as long as you have measured the force at any radius that you wish to use. (this also gets a little hairy quickly)
We know it bends light rays. A least according to our perceptions.

Einstein postulated that mass curves space and (poetically speaking now) orbits can be described as straight lines (inertial motion) in a curved space-time.

These are some of the reasons behind my earlier observation that the very nature of reality soon bumps into relativity.

When we go to bed why don't we just bounce up

As a matter of FACT, damned if I KNOW. Apparently nobody else does either. .


Another small thought, "Knowing that we do not know may be the beginnings of wisdom"

There is an effect of gravity that has amazed me ever since I realized it exists -- and I'd like at least to mention it for its interest value to the group.

If two galaxies crash into each other -- two interesting things happen.

One -- there is almost no collision of matter. The suns of each galaxy have so much space between them, it appears as though there relatively infrequent occurances of two suns colliding at the galaxies pass through each other.

Two -- the gravity of each galaxy remains relatively intact. Even though the interaction may extend over millions of years, the stars of one galaxy pretty much pass through the stars of the other -- and the passing galaxy emerges the other side pretty much intact.

Both these items have lots of exceptions -- and obviously, the data upon which these conclusions are based is relatively scarce. Most of the science and observations which go into these phenomenae are less than 70 years old. The science is brand new. And, the agnostic in me demands that I at least acknowledge that no scientist can say with certainty what happens when galaxies collide.

But perhaps Mech will commnet on this issue.

Yes Frank, I love that one,
I helped my now 37 year old daughter set up a demo on densities of the Universe for her Jr. High Science Fair.
It works out to less than three marbles scattered over the world. Stand on Mars and throw three more marbles at Earth (thats the bluish planet that you see on Mars as a morning or evening star. The chances of your thrown marble hitting one of those resting on Earth is similar to the odds of a star collision.
Then if you realize that the Universe may be truly infinite that implies that all mass is gravitationally bound and that all probable collisions have already happened the odds get even longer.

(IF anybody wants to call me on that last sentence I realize that already is a meaningless term in infinity. This analogy is a bit poetic as opposed to being mathematically precise.)


A disclaimer-- We had worked this out before Steven Hawkings and the Chandra telescope array had theorized and observed "Black Holes" We may have been a marble or two off one way or the other.
Best all, M.

ebrown, Olbers's paradox has been resolved: actually there IS something everywhere you look in the night sky: the cosmic microwave background radiation which is a relic of the big bang. We don’t see it because it is red-shifted out of the visual spectrum.

Kepler calculated that the night sky would be bright if stars were evenly distributed for a distance of 10^^24 light years, but we cannot and never will see any of the stars beyond the CMBR horizon, ~13 billion light-years (not counting expansion effects). Stars beyond that point are simply not old enough for their light to have been traveling long enough to get here.

Same thing applies to gravity. Since the speed of gravity is thought to equal the speed of light, gravitational forces of stars and galaxies beyond our event horizon would not be felt.

Can you give us an idea of why those brilliant minds think that the universe is finite? Last I heard, the issue was not yet resolved and they needed to postulate a LOT of mysterious and undetectable dark energy and dark matter just to keep it together.

And our observable universe may be only one of an infinite number of universes in an infinite multiverse.

Mech, the math has been done. Not only is the universe expanding, but the rate of expansion is increasing. The CMBR, relative abundances of elements, and other data point to its birth in a big bang type event about 13 billion years ago.

The Hubble Constant HAS been determined within 10%, in several different studies. I gave you links on Abuzz.

The big bang was not the basic premise of Hawking or anyone else. Inflationary big bang theory replaced the steady state universe theory simply because it best explains observed data. It will stand until someone comes up with a better theory - and can do the math to validate it.

BoGoWo, yes, the gravitational effects of planets and even distant stars can be "felt" on earth. But their effects are dwarfed by variations in gravitation force due to local terrain (gravity diminishes at higher elevations and rocks are denser than water) and the movement of the moon and sun.

The effects of seasonal changes in diet, activities and weather probably have far more effect on the developing personality of an infant than the miniscule effects of distant stars.

Frank, it is mind-boggling how vast and empty the universe is. And to think that God would have created zillions of planets in billions of galaxies, and his major concern is the sexual proclivities of people on this one! :wink:

Terry, Good point. It's not only 'sexual proclivities.' I bet someone with knowledge of the bible can come up with many more. c.i.

Great responses from Mech and Terry (and ci). I thank you all.

Can anyone comment on the fact that individual galaxies that take millions of years to pass through other galaxies -- manage to retain most of their original form. The tremendous gravity of the other galaxie -- while admittedly there is some distortion -- doesn't seem to distort as much as one would expect.

Anything?

TRUTH
Good discussion, folks. I have nothing to contribute, never reading about astronomy or astrophysics. But let me drop this: The finite-infinite contrast has never made sense to me. First of all, infinity is well beyond my imaginative capacity (it's no more than the opposite of finitude), and since that is so, the "finitude" of objects cannot follow sensibly because that meaning rests on its complementary contrast, infinity.

Terry, re your post of Jul 21 9:34AM
I hate to waste your time since I have so much more of it than you do.
You and I have been on opposite sides of a great divide for some time now. This, believe it or not, has been very helpful to me. I am still wading through your links. Thank you for them. I am also finding a few more of my own thanks in part to a local "adult education course" about using the "net".

1. The math has not been done satisfactorily. At least it has not been done the way a mechanic or engineer would do it. If somebody has done it without postulating an inexplicable occurrence then it must have happened since 1996. (Publication date of "Cosmology and Controversy"
(the historical development of two theories of the universe) Princeton Univ Press.
2. The Cosmic Microwave Background Radiation (CMBR) is ambiguous.
It apparently is predicted by both major theories. The Einstein-DeSiter Universe is one model that predicts it in an infinite Universe. That was about 1929. (this is the basis for my comment some time ago) "It's not to hard to predict something if you already know the answer" referring to the "discovery" of the CMBR.Quantum Mechanics satisfactorily explains (IMO) the temperature (amplitude).
3. I will look up newer news. The last time I looked the Hubble Constant was ranging from 30% to 90% of what relativity would predict for objects that we have other checks on.
4. My impressions of Hawkings premises are different than yours.
5. My quest is to find someone who can understand both the mechanics and the math involved. So far I feel like Sir Lancelot, and perhaps I am destined to an equally fruitful quest, but I don't intend to quit until I am able to understand the math in four dimensions.
6.Math which requires unknowable dimensions to describe the four that we are stuck with is in error before it starts. IMO natch.


Wether the error is in the theory, the perception, the math, or in the conclusion I certainly don't KNOW. Currently I'm betting on Albert and Issac. They've done awfully well so far.

Sometime I expect to be able to describe a "mechanical" Universe that will agree with more of our perceptions than the current model does.
Its taking longer than I thought, but at least I have plenty of time
There are already several Universes out there being kicked around, Most of them by Phd's. Whats one more? Best, M

Re: the universe and space....?


This is a question for theoretical physics, not philosophy. Sufficive to say, that space and time are a property of the universe. They have no meaning outside our own universe. Your question is based on the one whopping assumption that the laws and properties that we observe to be true withen the boundaries of our universe also apply outside of our universe. Also, the universe is not infinite, but it has no boundary - get your head around that.

Hello ILZ,
The quest for a beginning has occupied mankinds spare time for several millennia. I think it fair enough to quest in philosophy.

I for one would like you to model a finite-boundryless Universe. You may need to work on some definitions also. Even coming up with a definition of infinite has been the subject of a few threads.

I am wishing for your success, I am reasonably certain that everybody here does also.