Posted on 12/06/2003 9:14:26 AM PST by John W
Edited on 04/29/2004 2:03:32 AM PDT by Jim Robinson. [history]
CAPE CANAVERAL, Florida (AP) -- NASA is relying on Russian-made thrusters to steer the international space station following a new malfunction with the U.S. motion-control system, officials said Friday.
Flight controllers detected spikes in current and vibration in one of the station's three operating gyroscopes on November 8. Last week, when the gyroscopes were used again to shift the position of the orbiting outpost, all three worked.
(Excerpt) Read more at cnn.com ...
In this lecture, I would like to discuss whether time itself has a beginning, and whether it will have an end. All the evidence seems to indicate, that the universe has not existed forever, but that it had a beginning, about 15 billion years ago. This is probably the most remarkable discovery of modern cosmology. Yet it is now taken for granted. We are not yet certain whether the universe will have an end...
The time scale of the universe is very long compared to that for human life. It was therefore not surprising that until recently, the universe was thought to be essentially static, and unchanging in time...
Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them. This kind of beginning to the universe, and of time itself, is very different to the beginnings that had been considered earlier. These had to be imposed on the universe by some external agency. There is no dynamical reason why the motion of bodies in the solar system can not be extrapolated back in time, far beyond four thousand and four BC, the date for the creation of the universe, according to the book of Genesis. Thus it would require the direct intervention of God, if the universe began at that date. By contrast, the Big Bang is a beginning that is required by the dynamical laws that govern the universe. It is therefore intrinsic to the universe, and is not imposed on it from outside.
Although the laws of science seemed to predict the universe had a beginning, they also seemed to predict that they could not determine how the universe would have begun. This was obviously very unsatisfactory. So there were a number of attempts to get round the conclusion, that there was a singularity of infinite density in the past. ....
If space and imaginary time are indeed like the surface of the Earth, there wouldn't be any singularities in the imaginary time direction, at which the laws of physics would break down. And there wouldn't be any boundaries, to the imaginary time space-time, just as there aren't any boundaries to the surface of the Earth. This absence of boundaries means that the laws of physics would determine the state of the universe uniquely, in imaginary time. But if one knows the state of the universe in imaginary time, one can calculate the state of the universe in real time. One would still expect some sort of Big Bang singularity in real time. So real time would still have a beginning. But one wouldn't have to appeal to something outside the universe, to determine how the universe began. Instead, the way the universe started out at the Big Bang would be determined by the state of the universe in imaginary time. Thus, the universe would be a completely self-contained system. It would not be determined by anything outside the physical universe, that we observe.
Well good grief, Alamo-Girl -- somebody please tell me about the derivation of these "dynamical laws that govern the universe," that are "not imposed on it from the outside."
Don't we need to first ask how does a law get to be a LAW in the first place?
How can it be said that something that is posited as spontaneously sui generis within the framework of space and time gets the "credentials" to govern space and time? Is the Universe a "democracy?"
If it is -- a democracy constituted by what?
The resort to "imaginary time" seems tantamount to making the case for the "imaginary thinker."
Why does the denial or evasion of the Divine aspect of life in the Universe seem ever to require such circuitous routes?
Exactly, A-G! We humans should definitely stick with "what works." But on the other hand, it seems to me that we also ought to inquire into what doesn't work, from time to time. And try to reimagine our problems in new, potentially fruitful ways.
You:
... or until the subject being researched requires new methods, procedures and assumptions. I think that is a point being raised by Penrose, Wolfram and others.
Yes. As I said: "... as long as something else isn't working better."
In other words, we must always remain open-minded to better ways of acquiring knowledge. (You know what I mean: information that is observable, verifiable, testable ...) The flip-side is that we must also be open-minded to the possibility that some attempts to find a better path to knowledge may not be successful. One must be open-minded to the truth, either way.
The theological significance of there being a beginning (whether universe or multiverse, young or old) is evidently understood by some scientists who, not willing to humble themselves before the obvious, torture their own theories for the purpose of denying God as Creator:
In my {always humble) opinion, you may have put an unintended spin on Hawking when you quoted him saying this:
Although the laws of science seemed to predict the universe had a beginning, they also seemed to predict that they could not determine how the universe would have begun. This was obviously very unsatisfactory. So there were a number of attempts to get round the conclusion, that there was a singularity of infinite density in the past...I take that to mean that it's "unsatisfactory" to have a problem with no solution. So they strive for further understanding. That's how science reacts to any problem. It's not necessary to assume a theological -- or rather, anti-theological -- intent on such curiosity.
Didn't the Communist Manifesto kinda cover that?
LOL, Patrick, you so funny! "Strive for further understanding," indeed!!! Sometimes I think it's more the reverse idea: Strive to run away from the seemingly obvious because it's "unacceptable." :^)
It seems like Hawking is trying to avoid all the "easy" answers to how the Universe got a beginning, and is torturing himself with the "hard" answers -- such that it came into existence in imaginary time, in some way we do not understand. Indeed; how could we understand it, if all this occurs in imaginary time?
How is an imaginary time to be understood?
Just ask yourself this: Where do the laws of the Universe come from? How do you explain that?
And who wrote the law that says that knowledge gained by one discipline cannot inform us when we seek to understand knowledge gained by another discipline?
Whoever that is, I'd hate to see his or her driving record.
Back to work, Merry Christmastime.
Oh that's right -- they don't let Hawking drive, do they?
Are you incapable of accepting a mystery that has no current explanation? Thousands of scientists worked, lived and died prior to the discovery of radiation. Discoveries will continue being made after we are all dead.
Amen to that.
Actually, I think he's analogizing from an area of calculus called complex variable theory. You get the same sorts of problems in complex variable theory - singularities in only one component of the function. 'Imaginary' refers to numbers which are multiples of i, the square root of minus 1. So, if you have the very simple function 1/x + i, as x goes to zero, the real part goes to infinity (a singularity) while the imaginary part remains as i.
Quantitles like time and position are usually considered to be purely real. However, a lot of other physical quantities are complex - that is, they have real and imaginary components. Most quantum mechanical wavefunctions are complex; the current in an electronic circuit is complex. I should mention the 'imaginary' part is no less important than the real part; it just so happens these quantities have the same mathematical properties as a number with a real and an imaginary component.
It's certialy worth exploring what the consequences would be of a complex time.
Is 'by accident' an acceptable reply?
I don't know. No one does. I can conjure up an explanation; anyone can. Virtually everyone has. It seems to be a univerally popular human pastime.
My provisional (and very Aristotelian) assumption is that the laws of the universe are inherent in the nature of matter and energy, and don't need to come from anywhere else -- if indeed there actually is somewhere else. But I can't prove any of this; nor can anyone demonstrate that the laws of nature have some other source. It's all speculation. The best we can do -- so far -- is to discover what the laws of the universe are; and it may be that we'll never find out their origin.
How did matter and energy acquire their nature or properties?
No, not really RWP (no surprises there I'm sure!!!). You would need to demonstrate how an accident can be the source of persistent, universal order in the face of astronomical odds against such a possibility. And then you would have to show how an accident can produce something that is immune to any further accident. I.e., if an accident is responsible for universal laws, then why could not another accident come along and wipe out the product of the first accident, and set up new laws?
That's really an interesting analogy, RWP. But I don't see the practical application to our present inquiry. (Maybe you could help me with that.)
I had thought that imaginary numbers are "abstractions" mainly used for practical reasons, as a (very ingenious) way to allow square roots of negative numbers to figure in various types of mathematical equations, which facilitates a wide range of scientific applications; e.g., plotting positions in modeled spaces, etc.
In other words, It seems imaginary numbers facilitate what we already know we want to get done -- they are means to an end. But what is the end, or goal, or purpose? The need to posit imaginary numbers seems to suggest that we already know what that end or goal or purpose is before we begin. So, by analogy, is there a "cosmic knower" who would use imaginary numbers in this manner, and thus produce a singularity? (Is Hawking the "cosmic knower" in this sense?)
Do imaginary numbers really figure in nature -- that is, are they discoveries by man of what is already "there"? Or are they inventions or artifacts of man, useful tools or "machines?"
More questions than answers, as usual, RWP! Thanks so much for writing.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.