the universe and infinity...

[Slartibartfast]

I don't believe in the big bang. for one, it defies conservation of energy, but you could just argue that the laws of physics were different back then.

But still, if the universe isn't infinite in time both ways, what was here before the big bang?

the one theory is that the universe has existed infinitely in time, but every thousand trillion years or so, all the matter in the universe contracts to a single point, then explodes, thus causing another "big bang" and the rebeginning of the universe. the theory states that this has been going on forever and will be going on forever. this is the most plausible, in my opinion, theory of the origion of the universe.

[Natsilicious]

Well dear,the LITTLE I do know about science is that it is not so objective as you claim it to be.
You are using other people's views to create your own and even now, knowing that you know a more about astronomy and physics have not given a figure to how many stars are in the sky. How do you know that the sources that you use are accurate in estimating the number of galaxies and star systems? (a 'hypallage' or something...using the term loosely)
you even said it yourself...(Very often what we think we're seeing is not necessarily true. )

Certain things have to be directly observed in order to obtain a near accurate estimation. I'm sure there is not a pattern to how many stars are in one place... and discovery of black holes is a totally different argument... and since u mentioned that , just a correction. you cannot discover something that you are already directly observing.



[/quote]

[ssivakami]

I don't believe in the big bang. for one, it defies conservation of energy, but you could just argue that the laws of physics were different back then.

It is not a question of belief, it is a question of evidence [:)]
And important as your beliefs may be to you, they are no indication of the validity of a theory.

But still, if the universe isn't infinite in time both ways, what was here before the big bang?

No space or time. The BB resulted due to random fluctuations of zero mass-energy into positive and negative mass-energy. So the total mass-energy in the universe is zero.
That you cannot imagine it doesn't really matter. Our brains evolved to survive and reproduce in the African plains and rainforests. It is not surprising that they are ill-equipped to deal with things like the origin of the universe. So we cannot rely on imagination and instinct for this one .. we have to rely only on evidence

- Sivakami.

[ssivakami]

Well dear,the LITTLE I do know about science is that it is not so objective as you claim it to be.
You are using other people's views to create your own and even now, knowing that you know a more about astronomy and physics have not given a figure to how many stars are in the sky. How do you know that the sources that you use are accurate in estimating the number of galaxies and star systems? (a 'hypallage' or something...using the term loosely) you even said it yourself...(Very often what we think we're seeing is not necessarily true. )

Because I know that it is based on objective evidence. And has been independently verified before and can be again. You and I could, with a little scientific knowledge verify/disprove these theories. It doesn't require any faith or belief

Certain things have to be directly observed in order to obtain a near accurate estimation. I'm sure there is not a pattern to how many stars are in one place... and discovery of black holes is a totally different argument... and since u mentioned that , just a correction. you cannot discover something that you are already directly observing.

Nope, direct observation is not always necessary and not always possible either. Science works like this ...
You have a hypothesis H. If H were true, using logic, scientists deduce that they should be able to observe a,b and c. Then they go out and observe. If they observe a, b and c (many times, independently) then the hypothesis is valid. But if they dont observe even one of those, it is invalid. Tomorrow if some other scientist comes along and fails to observe c under a certain circumstance or finda nother phenomenon d that should be observed if H were true, but isn't, then again H is disproved.

- Sivakami.

[Natsilicious]

no sivakami, science still isn't very objective. Scientist use paradigms to achieve answers...this is in no way an objective pursuit of knowledge so therefore it doesn't aim to falsify but confirm theories etc...

For example, u just said :"You have a hypothesis H. If H were true, using logic, scientists deduce that they should be able to observe a,b and c. ....." you see, there is a standard procedure for retrieving information in your view; it guides how that evidence it collected and how it should be analyzed and explained.

Can it then be seen as objective??..

Natty

[ssivakami]

no sivakami, science still isn't very objective. Scientist use paradigms to achieve answers...this is in no way an objective pursuit of knowledge so therefore it doesn't aim to falsify but confirm theories etc...

Every scientific theory has an explicit falsifiable clause. Else it isn't a valid theory at all . Its religion that states unfalsifiable theories - convenient for belief without evidence

For example, u just said :"You have a hypothesis H. If H were true, using logic, scientists deduce that they should be able to observe a,b and c. ....." you see, there is a standard procedure for retrieving information in your view; it guides how that evidence it collected and how it should be analyzed and explained.
Can it then be seen as objective??..

What standard procedure ? The only procedures science follows is logic, objective evidence and skeptical scrutiny. Its only in science that scientists actively try and disprove their own theories and invite other scientists to disprove theirs. Only after theories have been subjected to intense peer review are they accepted. Even then anyone who reveals evidence to the contrary can disprove it anytime.

- Sivakami.

[Natsilicious]

Come on sivakami, we both know that science doesn't only follow 'logic' and further more logic means conformity to laws. Subjectivity.

And scientists aren't all that eager to falsify claims because they might ruin their reputation/credibility because of fear of being wrong. I'm sure not every scientist is as passionate as you are. Some are just in it for the money. and you know that's the truth.

[ssivakami]

Come on sivakami, we both know that science doesn't only follow 'logic' and further more logic means conformity to laws. Subjectivity.

No, I dont know that science doesn't follow logic. It also uses some basic assumotions and continuously validates hypothesis with evidence, yes. But it certainly uses logic. Without logic we could not form hypotheses.
Conformity to laws is subjectivity ? How ?
Of course the proof of the pudding is in the eating. And we've all eaten and enjoyed the pudding as far as science is concerned. We do it everyday, almost continuously.

And scientists aren't all that eager to falsify claims because they might ruin their reputation/credibility because of fear of being wrong. I'm sure not every scientist is as passionate as you are. Some are just in it for the money. and you know that's the truth.

Scientists are but human, but the very process of science ensures that subjective biases dont hold for long. Their very jealousy ensures that each new hypothesis is out under the most intense skeptical scrutiny and comes out only after it has passed it. Sure, scientists are human. But they accept their wrongs and correct themselves far more easily than those of any other discipline. Science thrives on skeptical scrutiny and self correction. The method has the process built-in.

- Sivakami.

[Magius]

I have loved astronomy since I was a kid and have had the pleasure of learning much about it in University despite my major being Philosophy.

So, I think I can help with some actual evidence. What has so far been proved is the following: we understand how the universe formed from 10 (power= -4) second. Which means we know what happened 10000th of a second after the big bang explosion. This time period is described as the Planck era.

Slartibartfast stated:
"I don't believe in the big bang. for one, it defies conservation of energy, but you could just argue that the laws of physics were different back then.

But still, if the universe isn't infinite in time both ways, what was here before the big bang?

the one theory is that the universe has existed infinitely in time, but every thousand trillion years or so, all the matter in the universe contracts to a single point, then explodes, thus causing another "big bang" and the rebeginning of the universe. the theory states that this has been going on forever and will be going on forever. this is the most plausible, in my opinion, theory of the origion of the universe."

But you contradict yourself, you say at the end that this is the most plausible theory, but at the beginning you state you don't believe in the big bang. Exactly how does the big bang defy conservation of energy? By the way, we can't know if the universe is infinite, we use to think the stars we saw in the sky were infinite. But now we know that even a planet or a star has an age, or I should say a birth and a death.

There are hundreds of billions of stars in our galaxy. The exact number cannot be known since, the amount of work needed to find, classify, and name billions of stars takes a few millenia. Moreover, there are some stars that we can't even see from earth because they are being blocked, by either other stars or interstellar gas clouds. The center of our galaxy is near the constellation Sagittarius and is about 8 kpc away from our sun.

One thing I would like to mention is that there is something in space, the theoretical vaccum. The reason I say this is because traditionally astro-physicists and astronomy students in general have been taught that there is a void in space, there is simply 'nothing'. This is not so, and it has been proven. There is what is called the <b>Cosmic Microwave Background for which Penzias and Wilson won the Nobel Prize in 1978. It is this very thing that proved to the world that the big bang really did occur. Reason being that theoreticians made theories as to the temperature of space at the beginning and if the big bang really did happen exactly how the temperature and energy would be distributed around the universe. These theories gave some theoretical temperature which the Cosmic Microwave Bachground confirmed.

Some things I do disagree with, for instance is the cosmological principle. Which states that the universe is perfectly homogeneous (same size everywhere - perfect circle?) and that it is isotropic (universe is and looks the same everywhere). I personally don't believe either statement, and have not seen proper evidence to believe either one. On the contrary, astronomers are quite honest at letting everyone know the there is no real basis for belief only inferences to their best ability.

What's your take?

[Natsilicious]

My take is that I was half right , If what you're saying is factual.

[Magius]

I apologize for forgetting to close my bold after Cosmic Microwave Background.

[JAZPgh]

The universe is infinite, the amount of matter is not.

That is, the universe extends infinitely far in every direction (theoretically obviously) but matter simply occupies an ever-increasing "sphere" of existence within the universe. Matter (and time) was created, for all intents and purposes, in the big bang, and has been expanding - from a singularity - ever since.

Therefore, the logical problems you present with regards to infinity, assuming I have it right, need no longer apply.

But haven't recent studies indicated that the universe may be contracting, not expanding, as previously assumed?

[JP]

But haven't recent studies indicated that the universe may be contracting, not expanding, as previously assumed?

Don't think so, though I could well be wrong.

Is there some web-page you can point me to (i.e. on the NASA website or summat) that says this?

[ssivakami]

But haven't recent studies indicated that the universe may be contracting, not expanding, as previously assumed?

No. The universe is expanding.
Whether or not this expansion will stop depends on the amount of mass-energy in the universe, and we've still not found enough to check the expansion and begin the contraction. Physicists recently discovered dark matter, but even that doesn;t seem enough. We're still looking for more, as yet undiscovered, bits of matter.
As of now, it seems as though the universe will expans to a cold death (it will take billions and billions of years, of course!).
However, we never know ehen new evidence may turn up.

- Sivakami

[Magius]

Quite true Sivakami,
the theories I have read about match what you have said, but also go a little bit further. The new theories propose that the bits of matter that are missing from theoreticians calculations could be neutrinoes that we have been trying to detect since the late 1950's, but till this day we can only detect about one neutrino a day with the best technology tens of metres underground where the absorbtion rate is suppose to be the highest. The problem with detecting neutrinos is ofcourse the simple fact that they are made up of almost no matter.

What's your take?

[Matthew]

I sat a cosmology A-level module today, and in the syllabus it states

"recall that it is currently believed that the mean density of matter in the Universe is close to, and possibly exactly equal to, the critical density needed for a ‘flat’ cosmology." (OCR)


Flat cosmology - for those who don't know - means the universe will continue to expand, but will tend to a finite size, i.e. the rate of expansion will decrease. In terms of mass-energy and density, this corresponds to the density of the universe equalling the 'critical density' - which in itself isn't a definite value because of the uncertainty in Hubble's constant.

However, surely this occurence would contradict Hubble's Law which states that the velocity of a body is proportional to the distance it has travelled - the constant of proportionality being the Hubble Constant. This is saying that the rate of expansion is increasing.

So surely there can be no such thing as a 'flat' cosmology?

(I don't mean to provoke an infinite number of posts about the competency of the exam boards - I'm sure that mundane babble has something on that.)

[Magius]

Matthew stated:

However, surely this occurence would contradict Hubble's Law which states that the velocity of a body is proportional to the distance it has travelled - the constant of proportionality being the Hubble Constant. This is saying that the rate of expansion is increasing.

So surely there can be no such thing as a 'flat' cosmology?

(I don't mean to provoke an infinite number of posts about the competency of the exam boards - I'm sure that mundane babble has something on that.)

Just because we have flat cosmology that doesn't mean the galaxy is not increasing, whether flat or not the galaxy can grow. Hubble contributed greatly to the cause of Astronomy among other things. Ie. He classified the galaxies and provided many convincing theories on the structure and life steps of galaxies. But it should be noted that it is not conclusively proven that our universe is expanding. As with everything in the universe there is as much of an outer movement as there is an inward one. Specifically in relation to galaxies. <i>Hubbles Classification Scheme</i> has not been able to classify and capture the nature of all types of galaxies, the list and individual characteristics of the galaxies we find the further we look has proven to be of exhaustive effort and patients, but we are nowhere near classifying all of them. Galaxies such as elliptical and spiral, O type or B type, there are so many that fit in variation with a few together, and some that hold completely new characteristics astronomers still don't know what to think of.
There are problems with Hubbles definitions and findings, such as the <i>cosmological redshift</i> which causes stars at extreme distances appear to have a Doppler Redshift regardless of whether they are moving toward us or away from us.
Furthermore, there is a problem with one of Hubble's foundational beliefs, that being the <i>Cosmological Principle</i> which states that the universe is isotropic and homogeneous. Mix this principle with Hubbles finding that no matter which galaxy you are in, it will appear as though every galaxy is moving away from you. This causes a contradiction in principle.
There is also the Olber's paradox.
And there is the problem of the <b>Cosmic Microwave Background</b> supposedly proving the Big Bang theory, which clearly states that the universe started everywhere at once. Yet, the temperature is spread out evenly throughout space, while at the same time never reaching 0K. It is measured to be at an average of 3 Kelvin right now. But it is also assumed that this temperature was much greater in the beginning, and is only declining with respect to the universes growth. Some believe that when the universe hits 0 Kelvin or close too, it will be time for the universe to collapse back on itself to reheat things and start the expansion all over again.

What's your take?

[Guest]

sorry to bring up such an old topic and im not sure whether the stuff im gunna say has already been said but here it is anyway.

about the universal expansion theory.. the thing is .. the galaxies themselves aren’t moving at all... its the "space" between them that’s getting bigger.. for some reason space is expanding, galaxies are being pushed farther and farther apart by the space between them.. so it would appear that a "property" of space is to expand. which is really weird no?...

see from what i understand there two major forces acting on the universe.. gravity and some kind of cosmological constant or expansion rate... both fighting each other .. one trying to get everything together and the other pushing everything apart.. and for 1 millionth of a second the expansion force won and we got the big bang.. then gravity over powered the expansion and slower it down .. but now because the universe is expanding at an accelerating rate the expansion force is beginning to win again....

so i guess, one day, the universe will be thing cold dark place... everything will be so far apart, stars will burn out because of thermal equilibrium ...UNLESS.. gravity some how overpowers ………....and this could go on for a while...

anyhow.. u said something about the universe collapsing in on itself.. there was a theory, Big Collapse theory, that said that eventually the universe will collapse in one itself.. and that because on this time out go backwards.. so u would live again in billions of years and do everything ur doing now, only backwards.. that’s so messed.. but im petty sure that it was disproved awhile ago….. but it was an interesting idea...

anyone here thinking of going into cosmology or astronomy? Or already is ?

[silver]

oops, that one's mine

forgot to login

[Magius]

I don't know how I have missed this post before...

silver stated:

about the universal expansion theory.. the thing is .. the galaxies themselves aren’t moving at all... its the "space" between them that’s getting bigger.. for some reason space is expanding, galaxies are being pushed farther and farther apart by the space between them.. so it would appear that a "property" of space is to expand. which is really weird no?...

Where did you hear about that? I would love to read more on that. I proposed a similar notion to one of my professors in my first year astronomy class to explain a paradox that is still unexplained. The being the concept of the universe being homogenous and asymetric, along with Hubble's finding that when stars are too far away they begin to contain a constant Red-Shift despite whether they are moving toward us or away from us, as well as the theory he proposed that no matter which galaxy you are in, when looking out of it, it will appear that all other galaxies are moving away from you. Emphasis on the fact that "no matter what galaxy you are in all other galaxies will appear to be moving away from you". There is an inconsistency in these findings, but it is cleverly cleared up when one imagines something similar to what silver has stated above...my view is a variation of what silver proposes. I believe that the force attracting things together is matter itself, the more matter the stronger the force. But I also believe that 'space' has something unique to it, whether it be that it's a vacuum or that it has nutrinos flying through it, or something else - that causes space to continually expand. Hence, if a star is moving towards us as one part per hour, and space is expanding at 0.99 parts per hour, it may appear that a thing is moving away from us at great distances because we are capturing more light from space particles (that are expanding in the space captured by our telescope - between it and the object) than of the object itself. Since we have to capture the light bouncing off the object to perceive it, and not the object itself. So its an illusion.

silver stated:

then gravity over powered the expansion and slower it down ..

That was so cute...slower it down , silver - I'm not laughing at you, we all make spelling mistakes. I think it is good to rejoice in mistakes that are comical.

Silver stated:

so i guess, one day, the universe will be thing cold dark place... everything will be so far apart, stars will burn out because of thermal equilibrium ...UNLESS.. gravity some how overpowers ………....and this could go on for a while...

Acually, what you said is the exact theory being postulated right now and with the greatest imperical facts behind it. There is a constant temperature to the space in the universe, and it is slowely decreasing. It would be interesting to know what will happen when the first atom encounters 0 Kelvin, then again.

Silver stated:

. u said something about the universe collapsing in on itself.. there was a theory, Big Collapse theory, that said that eventually the universe will collapse in one itself.. and that because on this time out go backwards.. so u would live again in billions of years and do everything ur doing now, only backwards.. that’s so messed.. but im petty sure that it was disproved awhile ago….. but it was an interesting idea...

This post would have been much more interesting had I not lent my astronomy book to a friend of mine at university. I will get back to you about the Big Collapse Theory, I can't even remember if that's what it was called.

silver asked:

anyone here thinking of going into cosmology or astronomy? Or already is ?

I am sort of considering it. I have always thought about stars, space, physics, etc - but found it a little too complex for me to engage. I have delved into serious astronomy books, but found myself bored half way through. Too many equations. I sometimes fantasize that one day I will be able to fly out in a ship with complete freedom and go where I wish, see what I wish, in the solar system atleast. The university I go to actually specializes in shuttle technology and programming, I thought I might get into that. But as it stands I am a philosophy major in my second year, I am going to try to double major in philosophy and physics - but I still have to get through the basics of physics to see.

What's your take?

[silver]

...... 10 years later..

i heard about the space expansion theory on a TV show called Cosmic Odyssey, except I think they cancelled it now which is really unfortunate because I thought it was great! I think it was only on on Tuesdays... well anyway, I’ve been keeping an eye out for it, but to no avail. everything I said in that post was either from that show or from my heard, so I haven’t really heard anything about expanding space from any other source. Well I have hread much about the ‘expanding universe’ but not about ‘expansion as a property of space’. But maybe that’s because I haven’t really looked for it. (looks like I’ll actually have a reason to go to chapters for my next visit ) Although im sure there something somewhere on the internet, I’ve tried entering ‘expanding space’ on search engines but I basically got the same thing I posted before… no in-depth stuff…

Hubble's finding that when stars are too far away they begin to contain a constant Red-Shift despite whether they are moving toward us or away from us

hey!.. is that so?... humm.. I always thought that anything moving away from a given point would be red-shifted )if looked at from the point) because it is moving away .. you know .. the whole Doppler effect. So if something was moving closer to the given point, it would be blue shifted. I didn’t know that when starts are too far away they give off re-shifted wave spectrums regardless of whether they are moving away or not.. i wonder why that is.. Or am I interpreting that the wrong way?
I think i heard somewhere that interstellar dust clouds in space cause us to see celestial bodies as red-shifted because the distort the light we receive from them ... maybe that’s one explanation, although i doubt it..

[silver]

A book that does kind of talks about this is: A brief History of Time
Except it goes off on a tangent with some really crazy symmetry bubble stuff that i just haven’t have that time to sit and re- read.. Slowly..! Also it’s expensive, and you have to get the illustrated version because the other one is suicide at least I though it was..
Magius,
If ud like, I’d be happy to lend it to you.. it might be of some help.. Also: The Nniverse in a Nutshell Even if they're not if any help, both are interesting books.. with some perplexing and brave pictures.. lol.. Anyhow, if you do come across them in a book store, I suggest looking them though.

[Magius]

Silver,
Well I finally got my astronomy book back from my friend, so I hope I will be able to carry on a more coherent debate.

silver stated:

I have hread much about the ‘expanding universe’ but not about ‘expansion as a property of space’. But maybe that’s because I haven’t really looked for it.

I will attempt to give you two different explanations. (1)Logical and (2)Factual+Theoretical (from my book - <b>Astronomy Today</b> By: <i>Chaisson and McMillan</i> in case you are interested - really good book). Firstly, you heard that the universe is expanding, given that it is possible to imagine that either everything in the universe is expanding together at the same time or that just space is expanding. Since it would be difficult to imagine that matter is expanding but space isn't - if this was the case than planets, stars, meteor etc would be dangerously close to each other by now, or will be in the future. Either of the two possibilities we choose contain the attribute of 'space' expanding. Out of the two possibilities, personally, I like the idea that space is expanding and matter is not. Coincidentally Hubble would agree, according to my textbook "We now recognize that Hubble's law describes the expansion of the universe itself. Although galaxies have some small-scale, individual random motions, on average they are not moving with respect to the fabric of space - any such overall motion would pick-out a "special" direction in space and violate the assumption of isotropy. On the contrary, the portion of the galaxies' motion that makes up the Hubble flow is realy an expansion of space itself. The expanding universe remains homogenous at all times...."

silver stated:

hey!.. is that so?... humm.. I always thought that anything moving away from a given point would be red-shifted )if looked at from the point) because it is moving away .. you know .. the whole Doppler effect. So if something was moving closer to the given point, it would be blue shifted. I didn’t know that when starts are too far away they give off re-shifted wave spectrums regardless of whether they are moving away or not.. i wonder why that is.. Or am I interpreting that the wrong way?

The way the book explains it is that at extreme distance relative to us the photons of radiation become stretched in wavelength causing the effect of the <i>cosmological redshift </i> as Hubble called it. Aside: did you know that Hubble was a boxer prior to classifying galaxies? I thought that was so weird, and interesting.

silver stated:

I think i heard somewhere that interstellar dust clouds in space cause us to see celestial bodies as red-shifted because the distort the light we receive from them ... maybe that’s one explanation, although i doubt it..

I heard that interstellar dust clouds are part of the reason why Olber's Paradox is a paradox no more. It blocks light rays from continuing to reach us. Which I also doubt, since dust clouds are known to move, and in moving would block other stars from our view while revealing the previous. But then again, it could just be argued that they move REALLY slowely, or are so far away that we don't notice them move and won't for another couple of thousand years.

What's your take?

[surreptitious75]

But havent recent studies indicated that the universe may be contracting not expanding as previously assumed ?

The observable Universe is definitely expanding but that however is just local cosmic expansion
So what the non observable Universe is doing cannot be known at least not at this point in time