How we know the Universe has not existed forever

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The question -- "How do we know the Universe hasn't existed forever?" has come up on a number of threads. The fact is we know quite a bit about the beginning of the Univserse.

First, a brief note on what it means to "know" a scientific fact. Of course we can never prove anything, but there are ways that we can be "darn sure". Certain scientific "fact" are widely accepted since based on evidence it is very improbable that they are incorrect.

Scientific facts have the following qualities (this is not a complete list):

- They are not contradicted by any experiment.

- They are testable and tested. Someone can make a prediction -- "if this is true than this will happen" -- then make a measurement that matches the predicted results.

- There is no other rational way to explained what is observed.

- They are peer reviewed. Scientific facts are discussed and questioned by the scientific community before they are accepted.

It also helps if they are explained by more than one area of science. If people working on cosmology get the same results as those working on thermodynamics, it is even more likely that they are correct.

The fact that the Universe has not been around forever is very certain and it accepted by the scientific community as fact. This fact has passed all of the criteria above.

HUBBLE AND THE BIG BANG
Edwin Hubble brought the "Big Bang" into public consciousness. He was studying the speed of galaxies and noticed something which at the time seemed strange. The further a galaxy was from us, the faster it was moving. Think about this for a moment. If the galaxies where all moving around randomly, this would not happen.

The only way to explain this is that the galaxies are moving away from a single place. If you think about what happened in the past, the galaxies must have been in the same place at one time.

This became known at the time as the "Big Bang" theory, and at the time it was just a theory. However what we have done since makes it much more than a theory.

THE PHYSICS OF THE BIG BANG
Scientists took this idea and used mathematics and physics to understand how the Big Bang could have happened. Especially interesting are Einsteins General Relativity and Chemistry.

The model (set of equations) that physicists used to describe the Big Bang say definitively that time started when the Big Bang happened. Of course this mathematical model was only a theory until it was tested by the criteria above. (I can explain more if you would like, but at this point it gets very technical and mathematical).

"But how do we test this?", you ask. Good question.

LOOKING BACK TOWARD THE BEGINNING
With the advent of very powerful telescopes we can look back in time. This is because light tkes time to travel. If we look at a star that is 1 light year the light we are seeing now left the star 1 year ago. We are not seeing the star as it is now, we are seeing it as it was in the past. We are looking back in time.

Of course with the Hubble telescope (the name is not a coincidence) we can see billions of light years away. We see the galaxies that are 10 billion light years away as they were 10 billion year ago. This lets us see how galaxies, and the universe, evolve over time. The very fact that no matter what direction we look the galaxies that are 10 billion years away are all at the same level of development is itself a pretty powerful confirmation of Hubble's "theory".

Looking back also gives us many more clues to the physics. We test the physics by saying, "If this theory is true, we should expect these frequecies of light from galaxies at this distance". Measurements taken by modern telescopes have proven these predictions correct.

BLACK HOLES - A TRIUMPH OF MODERN PHYSICS
One of the major victories for these theories was the prediction of black holes. Physicists predicted them and described them long before they were detected. Incidently our scientific understanding of time, including the fact it is finite, is crucial to understanding black holes. I highly recommend "A Brief History of Time" - by Stephen Hawkings, if you would like a good laymans understanding of this.

HEARING THE BIG BANG
Another powerful confirmation of the Big Bang theory is Cosmic Background Radiation. In the late 1940's physicists predicted that if our understanding of the Big Bang were correct, there should be leftover radiation from this event.

Twenty years later, two engineers discovered and measured this radiation by accident. We now have a satellite (COBE) that was built to study this radiation for even more clues to the Big Bang. A good link for this (and other topics ) is
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest3.html

THERMODYNAMICS - AN INDEPENDENT CONFIRMATION
The field of thermodynamics also agrees with the fact the Universe can not exist forever. The laws of thermodynamics (which have their own set of very convincing confirmations) say that there is a finite amount of things that can happen in our Universe (the actual law is mathematical and too technical for the scope of this discussion).

But, it should be reassuring that we get the same answer from a completely different approach to the problem.

THE PROVEN FACT
Scientifically the fact that the Universe has not existed forever has been proven as much as anything can be proven. People have the right to doubt anything -- some people still insist that the Earth is flat -- but there is overwhelming evidence to say that we have it right.

- There is no other reasonable alternative that does not break fundamental scientific laws.

- This implications of the fact has been tested and has passed every test.

- This fact has been studied and tested by scientiests for some 50 years. It has be debated and written about extensively. After this has been accepted as fact by the scientific community.

DEBATABLE AREAS
It is clear that the Universe has not existed forever. There are auxilliary questions that are still being debated.

Questions about other Universes, or what happened "Before" the Big Bang are wide open. However they are impossible to study with science and therefore are currently more philosophical questions than scientific.

If there is an infinite creator, it is clear that She lives outside the Universe(or she would not be infinite). There is no way for science to prove or disprove the existance of such a creator.

There are some interesting scientific questions about the nature of the Universe that have to do with how it started and how it will end. Questions about whether we are in an "Inflationary" universe, its exact age, and its future are still open scientific questions. It may be that we prove scientific facts about these issues in the future.

Eric Brown-Munoz

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eBrown
eBrown, WOW! An elegant explanation for us non-science people. Thank you.

As a non-believer, I'm fascinated that humanity had to invent the concept of an infinite creator (God) thousands of years ago because they lacked the knowledge or tools to understand the scientific model. What gives me pause is why we continue to cling to the God model so long after we attained scientific sophistication.

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eBrown

Thanks for the essat -- and for the huge amount of work that obviously went into it.

HOWEVER -- a major problem arises almost immediately which tends to negate almost every specific mentioned in it.

If we are defining the Universe to be only the stuff that resulted from the Big Bang -- everything mentioned might indeed be correct -- and still we could have the universe be infinite -- not finite.

The reality, could, for instance, be that everything in the universe including space, time, and Spacetime -- has existed forever (infinitely) and that it periodically coalesces to a super dense state and Big Bangs over and over.

This is recognzed almost incidentally in the comment "Questions about other Universes, or what happened "Before" the Big Bang are wide open. However they are impossible to study with science and therefore are currently more philosophical questions than scientific. "

But that is absurd.

To suggest that it is almost certain the universe is finite without knowing any of that is cheating.

And, it is also possible that what we call the universe (the stuff of the Big Bang) is nothing but an insignificant speck in a UNIVERSE so large we cannot even comprehend it at our present stage of development.

Eric, your pronouncement "It is clear that the Universe has not existed forever" is presumptuous, gratuitous, and unsupported by the "fact" you yourself are offering.

BOTTOM LINE: We do not know if the universe is finite or infinite -- and although recent science has given great impetus to a notion that the stuff we call the universe is a product of a Big Bang -- it knows absolutely nothing about what came before the Big Bang -- or whether or not the stuff of the Big Bang is all there is or merely part of some greater whole.

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Frank, there is no problem.

It is clear that the Universe has not existed forever. Forever means that there has not been an infinite amount of time. This has been proven scientifically in more than one way.

What we measure as "time" (admittedly there are different ways of measuring this, but this is true for all of them) is finite. Any other hypothetical Universe would have to have its own time.

If you are going to speak of what happened before the Big Bang, *you* have the problem. Before refers to an earlier time. Science contends that time started with the Big Bang. You will need to tell me what definition of time you are using.

Science has the ability to prove facts. It does this by making theories based on observation, considering and disproving all althernative explanations, testing implications and enduring debate.

Some 500 years ago Scientists used the same reasoning to prove that the Earth rotated around the Sun. They proved this long before we knew anything about the scope or nature of the galaxy.

We used this process to prove the Earth revolves around the Sun, and we used the same process to prove that the Universe (and time) had a beginning.

You do accept that the Earth revolves around the Sun? Don't you?

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Eric

I assert that we do not know if the Universe is finite or infinite.

Of course, if you want to define "the Universe" as being "that which resulted from the Big Bang" -- you are correct, because "that which resulted from the Big Bang" seems almost certain to be finite.

But to suppose that "that which resulted from the Big Bang" is all that there is...

...is not especially scientific or logical.

In fact, it resembles the kind of thing that went into earlier assumptions that the Earth was a pancake flat object situated smack dab in the center of the Universe.

There are posters in A2K who were alive when Hubbel discovered that what we thought was the universe (the Milky Way Galaxy) -- was not the Universe at all -- but just a rather insignificant part of it.

Now you want to assume that present day science is the last word about what the Universe actually is -- what constitutes the Universe.

As I said in my earlier post...

...your assumptions are presumptuous, gratuitous, and unsupported by the "facts" you yourself are offering.

But if you want to "believe" the Universe is finite -- go with it.

I will stick with "I don't know -- and it appears neither does anyone else now alive."

I like my position much, much better than yours.

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OK Frank,Let's not fight.

I accept your definition of the Universe as "That which resulted from the Big Bang". I agree with you that that nothing has been proven about any other Universe - or anything in a Universe defined in any other way.

I will disagree with you on one small point.

This definition of the Universe is most definitely scientific and logical. Science (and for that matter logic) are based on making conclusions based on what we can observe and test. Statements that can not be tested are not part of science.

The Universe that started with the Big Bang is the only thing that offers itself to scientific study.

But as long as we are studying things in the scientifically defined Universe, science has a lot to say.

The question "Has the Universe been around forever?" is a scientific question. It deals with the Universe that we can observe and test.

Of course if you make up your own non-testable definitions of time and space, science is of no use to you, and this question enters the realm of philosophy.

You are questioning the value of science. This is, of course, a philosophical question that I will not argue here.

I am saying that inside of a scientific context - using the scientific definitions of space and time- it is clear that the Universe does not contain an infinite space, nor has it existed forever.

Whether science is presumptuous or gratuituous is subjective. It is certainly not unsupported by the facts.

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Okay, Eric.

I disagree and disagree strongly.

But I do agree that we should not fight.

So I will leave things where they are.

And if we are ever in a discussion or debate where the question of whether or not the UNIVERSE is finite or infinite becomes essential -- we will hash things out further at that time.

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ebrown, You make valid points about our universe that is understandable for us non-scientific types. Greatly appreciate the time and effort you have put into explaining the scientific theory of our existence. c.i.

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Frank Apisa wrote:

If we are defining the Universe to be only the stuff that resulted from the Big Bang -- everything mentioned might indeed be correct -- and still we could have the universe be infinite -- not finite.

The reality, could, for instance, be that everything in the universe including space, time, and Spacetime -- has existed forever (infinitely) and that it periodically coalesces to a super dense state and Big Bangs over and over.

I'm behind Frank on this. Could the entire universe simply come into existence for no actual reason at all? Avoid it by calling it beyond the realm of science or define it away, but if nothing happens without a cause then what happened beforehand to trigger the big bang? But then there's the question of what that something was caused by, and so on. And if god created the universe, who created god? This line of thinking gets uncomfortably difficult very quickly.

But at any rate, saying the universe has always existed doesn't explain its existence. For example, take the idea Frank mentioned where the universe big bangs over and over...what then caused the original Super big bang? Maybe the origin of the universe wasn't the instant appearance of matter in an eternally existing void, but the coming into being of time. But then why would time suddenly switch on?

Still, something that just happens doesn't need to actually violate the laws of physics, but that's delving into quantum physics, and the rule of law is replaced with a form of anarchy or chaos--in which case it's not provable.

Maybe we're all looking at the problem the wrong way.

Here's an article I recently found on google news...It provides conflicting evidence, for both sides of the question.
http://www.newscientist.com/news/news.jsp?id=ns99994250

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I also believe Frank's idea has merit. I doubt we'll ever learn the whole truth, and many scientific theories will be forthcoming.

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I think e brown and Frank are approaching the issue from different points of departure.

e brown is arguing from an empirical perspective, about facts that can be tested, and about the mesurable physical universe. Frank is arguing from an agnostic prespective about what isn't mesurable, or what we haven't been able to mesure, yet. He is arguing about the possibilities beyond what we know.

Taking these differences into account, e brown is right. The physical universe, as it is mesurable, is un-uniform, inconsistent and finite.

I also agree with what Frank says, "But to suppose that "that which resulted from the Big Bang" is all that there is...

...is not especially scientific or logical."

There are theories of the universe that are completely mathematical and/or philosophical that try to account for the discrepancies and problems of the Big Bang theory. As such, they are purly theoretical, but the ideas are there.

Here are some of those theories:

The Bouncing Universe

In the 1960's, a physicist named John Wheeler developed the bouncing universe theory. The theory's premise involved having a universe come into being with a bug bang, expand for a while, and then implode at a certain point in time. Upon reaching reaching a certain small size (maybe even a singularity), that universe may "bounce" and re-explode in a new big bang. As a result, the universe follows a cyclical pattern of expansions and contractions.

The Protouniverse

This theory involves the formation of matter from nothingness before the explosion of the big bang. It is related to the white hole theory. A white hole is a theoretical opposite of a black hole, wherein matter would continuously appear at the speed of light, as if from nowhere. Although there is believed to be no observational evidence of white holes, the protouniverse theory was created in an attempt to explain the non-uniformity and the varying density of the universe.

The Inflationary Theory

In 1981, a particle physicist named Alan Guth created a new theory. Guth knew about the matter in physics that explained how elementary particles got their mass. This matter is called scalar field matter. Combining the mathematical equations for scalar field with Einstein's equations describing the expansion of the universe, Guth developed a theory in which large amounts of matter and energy were created from nothing! After matter and energy were created, the universe experienced an accelerated expansion, becoming exponentially large prior to continuing its evolution according to the big bang model. This theory has been worked on and modified by many cosmologists since its introduction.

The Bubble Universe / Andre Linde's Self Creating Universe

The bubble universe concept involves creation of universes from the quantum foam of a "parent universe." On very small scales, the foam is frothing due to energy fluctuations. These fluctuations may create tiny bubbles and wormholes. If the energy fluctuation is not very large, a tiny bubble universe may form, experience some expansion like an inflating balloon, and then contract and disappear from existence. However, if the energy fluctuation is greater than a particular critical value, a tiny bubble universe forms from the parent universe, experiences long-term expansion, and allows matter and large-scale galactic structures to form.

The "self-creating" in Andre Linde's self-creating universe theory stems from the concept that each bubble or inflationary universe will sprout other bubble universes, which in turn, sprout more bubble universes. The universe we live in has a set of physical constants that seem tailor-made for the evolution of living things. (emphasis mine)

from http://web.uvic.ca/~jtwong/newtheories.htm

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What is "the universe"?

Is it everything within the range of our perceptions? Is it everything we are capable of measuring? Is there only one of these items?

Is it possible that some of the surmised-to-be-known aspects of the universe that we currently admit to lacking information about (such as dark matter/energy, such as the nature of the mathematical curleques that allow for the decadimensional models of thread theory) will, upon further revelation, open up a greater awareness that will make our current state of knowledge seem primitive?

I believe so. I cannot believe that in just the last three or four hundred years we have plumbed the mysteries of the vastness around us. I feel humble in the face of it all, and have to wonder at those who give credence to our mastery of all this knowledge.

I'm not a luddite, or scientifically illiterate... quite the opposite: I follow science and particularly cosmology with great interest. I just think the human mind contains within it an impressive and all encompassing vanity, that blinds us and convinces us that we are always in the anteroom of awareness when, in fact we are still just knocking on the door.

:wink:

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Maybe, we still haven't reached the door. Wink

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InfraBlue (as our discussion has properly moved to a more relevent thread),

Three of your theories deal with what happened "Before" the Universe started. They are interesting, but the are not currently testable and therefore are philosophical theories, not scientific ones. Incidently since time started when the Universe started the word "Before" has problems.

The "Inlationary Universe" theory is a scientific theory since it deals with facts that can be tested. This theory assumes that there was a beginning with the Big Bang. The question that this theory addresses has to do with the End more than the Beginning.

This theory is being tested as we speak is still be discussed. It has not been conclusively proven or disproven.

Furthermore,

It is possible mathematically and scientifically to prove things based on facts you you know, even when there are things you don't know.

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Also ... It is certainly possible that God created the world yesterday.

The theory would go: We were created with all of our memories intact -- and the world was fabricated with its historiecal record. The light from distant stars was created in its proper place to appear to have left billions of years ago etc. etc. etc.

There is absolutely no way for science to disprove this theory. This is not a scientific theory.

Science states emphatically (for the reasons that I stated above) that the Universe has not existed forever. I say this because if you follow the scientific method based on measurable facts you will come to this conclusion.

You can question the value of science -- and perhaps you are. But, this type of scientific reasoning has been crucial for us to split the atom, land on the moon and even build the computer you are reading right now.

Science can not answer all of the questions we have. However for questions regarding the nature of the Universe, science offers a powerful tool.

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We have the universe model right before our eyes
I am not a scholar. Perhaps A2K scholars can explain to non-scholars the following question.

It seems to me that we have an acceptable model right before our eyes.
The model is constantly repeated throughout our galaxy and what we can see and know of our universe. The spiral model is evident throughout our visible universe. Is it reasonable to think that our universe might be based on that model? Spirals form naturally in our universe and on earth. Why should our universe be different than one of the most successful models already known?

That model also lends itself to another model we see. That of multiple spirals throughout the universe. Does this mean that our universe is only one of many. Are their multiple universes? And, if there are multiple universes, each with its own black hole, just like spiral galaxies? Why isn't it possible that these universes repeatedly explode and implode.

I realize my non-scholar observations and questions are simplistic, naive and unsophisticated. But I'm puzzled why scientists keep looking for more complicated answers than might be understood by simplifying rather than complicating their quest.

BumbleBeeBoogie

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Thank you for that explanation, it was helpful especially because physics is not my area, and you were gentle. I am actually reading "A Brief History of Time," although slowly and at my leisure. There are only two problems I can see in your assertion. One is that you assume it is right because all of the other theories are wrong. This would make it the most rational current choice, but maybe the correct theory has not yet been invented. Also, you are limited to the scope of what the hubble can observe - light waves traveling through space. This can only go so far, and the universe (meaning - everything) may go farther than is able to be observed, or be limitless. Because you cannot observe it does not mean it does not exist.

Are there other points of evidence? Like with sound or some other observational/testing method?

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Portal, please read my post again. I did not "assume it is right because all ofther theories are wrong." It is true that all other theories are wrong, but this is combined with quite a bit more evidence that the theory we have now is correct.

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At the risk of appearing to pose a sophomoric point here I would like to bring up something that most blossoming intellectuals come upon in their probing of all this cosmology stuff. It is the question or perception of vastness as outward as opposed to inward looking. The farthest quarters of the universe, the ancient stars of long ago and far away, are one boundary. The other, less obvious boundary, is the limit of
microcosmic infinitude. We currently divvy the particles down to quark soup, but among the quarks there are flavors, suggesting substructure. Substructure suggests subsubstructure. If we are limited in our ability to plumb the smallest, we are rexflexively limited in the outward direction.

I will hold hard to my position in this debate. I think we have not got sufficient information to make any proper judgement in these areas. Not saying we may never grasp the 'bigger/smaller picture, just suggesting the needed clues are still far from accumulated.

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You are quite right, Beed, there is not nearly sufficient information available to us to make the kind of statement Eric is intent on making.

Eric seems to be a very, very bright individual, but he certainly seems to have a blind spot on this issue.

You may be interested to know that I have used the micro aspect of possible infinity for years now. To me, it seems reasonable to suppose that if infinity exists -- it has to have more than an outward component. Scientists keep supposing that they have found the final indivisible components of matter -- only to find something else later.

I am agnostic on religion.

I am every bit as agnostic on science.

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How we know the Universe has not existed forever

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