Parallel Universes by F.A. Wolf - ...questions

Palomar · 2003-12-05 19:44:09

*I'm reading a book by the above title (I posted about this book in the "Good books you've recently read" thread). It's a book about physics for the "general reader" (sometimes political correctness is okay by me!).

Of course the discussion steers into topics such as Space, Time, Matter, etc. He says: "Matter was also [post 1900 AD] thought of in a new light. It was produced by the universe itself as a knot in the fabric of spacetime. It bent space as it curved time."

Here's my question: I thought time was merely a concept. Apparently not, for how can a concept be curved?

As many of you know I'm nowhere near to giving Robert Dyck a run for his money in the Physics Department, so any responses written in a general manner would be greatly appreciated (i.e. things like "Well, Horatio's Ratio of 6^sl\555% multipled by vq5 to the zillionth power of pi..." likely ISN'T going to be understood by me, teehee [unfortunately]...just a fair warning before you expend some keystrokes on behalf of the question).

Time: A concept? No? It can be curved? How?

Any comments? It would be appreciated.

--Cindy

Byron · 2003-12-06 07:12:22

Hmmm...I've never heard of "curved time" either. Exactly when was this book published?

I understand (or at least pretend to..lol) the idea of curved space caused by the presence of matter...like those coin funnels you see at the mall, where you put a coin in along the perimeter and it rolls around to the bottom, which I think is a good analogy for gravitational wells of stars, planets, etc.

One idea I have of looking at the universe and time is to imagine a huge, long cylinder, stretching from the beginning of this present universe, and extending to the end. If you take a cross-section of that cylinder, that represents the physical dimensions of space (the physical width and breath of the Universe.) The position along the length of the cylinder represents time (the "when" of things.) The present moment (what is happening right now) is a wave that moves along the length of the cylinder, which allow things to "happen" instead of being a frozen data point somewhere in time (history or future.)

Now, if we do view time as a wave (which makes the most sense to me anyhow,) I suppose you could see time "curving" physical space as it "passes" along my make-believe cylinder...this passage allows things like atoms to move, stars to shine and us typing on computer keyboards.

I'd better stop now before I get in too deep...lol...

Any other comments / ideas about this??

B

Palomar · 2003-12-06 07:57:17

Hmmm...I've never heard of "curved time" either. Exactly when was this book published?

*The book was published in 1988.

The author is a PhD and has written other books as well.

I thought time was merely a human construct, a *measure*...like inches or centimeters. For purposes of orientation, etc. ::shrugs::

--Cindy

Shaun Barrett · 2003-12-06 08:00:25

Always a tricky topic!
A massive body is thought of as bending space and thus causing a gravity-well, which things can fall into. I find this a fairly intuitive scene, as long as you don't think too hard about it!
But space and time are intimately entwined, according to Relativity. When you bend space, you must curve time also. This has been found to be true in, fact, and time in a gravity-well passes more slowly than time outside it. (Not that there really is an 'outside' of a gravity-well, of course, because any gravitational field theoretically extends to infinity. But let's ignore that detail for the sake of argument.)
If you had two clocks, one on the ground and another hovering, say, 1000 kms above the first, the one on the ground would lose time compared to the one at altitude.

In Relativity and reality it seems time is rather more than a concept.

[P.S. My favourite description of it is: 'Time is just nature's way of keeping everything from happening at once'.]

Byron · 2003-12-06 10:10:03

[P.S. My favourite description of it is: 'Time is just nature's way of keeping everything from happening at once'.]

Indeed!

B

Palomar · 2003-12-06 10:18:10

Shaun: "This has been found to be true in, fact, and time in a gravity-well passes more slowly than time outside it. (Not that there really is an 'outside' of a gravity-well, of course, because any gravitational field theoretically extends to infinity. But let's ignore that detail for the sake of argument.)"

*Hmmmmmm. Technically speaking there's no "outside" of the gravity well because it's simply a deep depression -but- is continuous of the gravity field. ?

Shaun: "If you had two clocks, one on the ground and another hovering, say, 1000 kms above the first, the one on the ground would lose time compared to the one at altitude."

*You know, I think you mentioned this analogy a long time ago. Someone did; I recalled this the moment I read it. So the clock 1000 km up is running faster than the one on the ground? Which implies that the stronger the gravity/gravitational pull, the more time slows down? That seems to be what you've said with the gravity well analogy.

Shaun: "[P.S. My favourite description of it is: 'Time is just nature's way of keeping everything from happening at once'.]"

*Mr. Wolf does discuss the concept of time not being the same everywhere. If I hadn't read his comments on that last evening, your statement would have totally thrown me.

--Cindy

Shaun Barrett · 2003-12-21 06:39:16

So sorry, Cindy!
I don't know how I missed your comments and queries here - must have been distracted by something at the time.

I'm not exactly sure what you mean with your question about the infinite nature of a gravitational field or well. I'll just describe it as I understand it and hope it provides an answer.
If we indulge in a thought experiment, it might help to clarify the point: Just suppose that our universe were suddenly emptied of all matter except two objects. They could be anything ... two marbles, two neutron stars, or even two medical transcriptionists!
Each of these two objects exerts a gravitational pull on the other one, so that if you placed them 10 metres apart, with no initial momentum in any direction, they would gradually accelerate towards each other. Even if you placed them 5 billion light years apart, they would still, ever-so-gradually and imperceptibly, begin to move towards each other!
In other words, each object's gravity well extends infinitely in all directions and every particle in our universe is influenced, however weakly, by the gravitational field of every other particle.
This wasn't really part of my reply to your 'time' question. It just kind of snuk in there by accident ... sorry!

As for the main question: "Which implies that the stronger the gravity/gravitational pull, the more time slows down?", the answer is yes!
This verified fact was predicted by Einstein's second relativistic tour-de-force, General Relativity. As I've confessed elsewhere, I have only a very rudimentary grasp of Special Relativity (which is 'easier'! ) and essentially no grasp of General Relativity at all!
So don't be tempted to ask me anything very much more complicated than the above or you're liable to be disappointed! (I suspect Pat Galea might be your best bet for really penetrating questions about Relativity.)

Palomar · 2003-12-22 12:01:25

So sorry, Cindy!
I don't know how I missed your comments and queries here - must have been distracted by something at the time.
I'm not exactly sure what you mean with your question about the infinite nature of a gravitational field or well. I'll just describe it as I understand it and hope it provides an answer.
If we indulge in a thought experiment, it might help to clarify the point: Just suppose that our universe were suddenly emptied of all matter except two objects. They could be anything ... two marbles, two neutron stars, or even two medical transcriptionists!
Each of these two objects exerts a gravitational pull on the other one, so that if you placed them 10 metres apart, with no initial momentum in any direction, they would gradually accelerate towards each other. Even if you placed them 5 billion light years apart, they would still, ever-so-gradually and imperceptibly, begin to move towards each other!
In other words, each object's gravity well extends infinitely in all directions and every particle in our universe is influenced, however weakly, by the gravitational field of every other particle.

*Hi Shaun. Okay, I get it now.

I initially misunderstood you. I thought you meant a gravity well was *synonymous with* a black hole.

My mind related the image of "gravity well" to the sinking-down (of gravity, i.e. depressing the space-time fabric) to the Singularity Point inside a black hole (which can be thought of, I suppose, as being like "a well"...the graphs in books kind of looks like a well).

Thanks for the answers -- I appreciate it.

--Cindy

Palomar · 2004-04-14 10:26:49

*Shaun wrote in a different thread a few months ago:

"Is the alternate universe into which all left socks and ball-point pens eventually disappear the same universe from which all the wire coat hangers originate?"

:laugh:

I couldn't help recalling that when I read the following, which is from Chapter 3 of the book, "Riding the Wave Through Parallel Worlds." The author has just discussed experiments through single and double slats with subatomic particles aka "waves." He says the theory of parallel universes came to be considered *seriously* because of the odd results from the slats experiments.

He says, "The only thing weird about it is the space and time that it moves through. When the wave encounters a situation that is logically impossible in a single world (a single spacetime region) the wave does something analogous to the way an ocean wave behaves when it encounters 2 or more spaces between piers jutting out into the ocean space. The wave splits apart." That's enough direct quotation from the book (don't want to get in trouble). :-\ Anyway, he goes on to say (my "paraphrasing") that one part runs off into one possibility, and the other into other possibilities. Also, that each possibility is a reality in a different world.

Okay, so he gives the example of a coin. You flip it; it lands heads in this universe and in the parallel universe (you guessed it of course)...tails. But then he goes on to say there are even MORE possibilities for the coin. :-\ ["The wave that represents the coin contains both possibilities. It contains even more possibilities for the coin."] It could land on its side; could suddenly absorb a great amount of energy and boil off into separate atoms;...and here's the funky possibility: It could disappear before your eyes only to reappear on the other side of the room. He says -anything- can happen, even if it's an "extremely remote" possibility, within the wave.

So...THAT'S what happens to left socks and ballpoint pens. :laugh:

Can't wait to get to the part about "zero-time ghosts." It's a really intriguing book; I should be further along with it by now, but I've always got my head in the 18th century otherwise...

--Cindy

SBird · 2004-04-14 11:32:17

OK, quantum wierdness time©!

First, I just wanted to add that time dialation by gravity is very well measured. In fact, GPS has to take the faster rate of the atomics clocks on the GPS satellites up in orbit for the system to work properly!

Anyway, the doubleslit experiment you mention is one of the two BIG QUESTIONS of science. The other is how to get relativity and quantum physics to talk to each other properly.

So, I realize that your book has covered this but I'll go over the experiment quickly for the benefit of others:

If you have a light source and a screen, light from the source will light up the screen - no suprise. Now, if you place another screen in between with a square hole in it, the light reaching the final screen is shapes like a big square - again pretty obvious. Right now, the observed phenomenon indicate that light can be either a wave or a particle, both are consistent with the observed results.

NOW, use a middle screen with a very skinny slit in it. You'd expect that if light were composed of photons, the ones that go through the slit should project a larger version of that narrow slit on the screen. This is not what happens. Instead, you get a fuzzy rectangle of light that fades off towards the edges. This can only be explained if light is a wave - waves diffract at apertures that are around the same size as their wavelength and basically reform into a new wave that heads out in all directions from the slit.

Now, use a middle screen with two such slits fairly close to each other and parallel. What you get is a series of light and dark stripes. This is further proof of the wave nature of the light since the two sets of waves coming from each slit are interfering with each other. It's hard to describe this with text but imaging two sets of ripples coming from a pair of rocks dropped in a pond. At some points, two wave crests or troughs will be at the same place and the water will go twice as high or deep. At others, a trough and crest cancel each other out and the water sits at the normal waterline. The light and dark stripes on the final screen are the same thing. At some points, the waves cancel out, at others, they reinforce each other and make a bright stripe.

HOWEVER, if one turns the light source WAAAY down and then uses a sensitive camera to detect light, it becomes apparent that light is hitting the final screen in discrete places. You see tiny flashes of light which proves that light is also a particle (photons). Therefore, light acts as both a wave and a particle.

The really wierd parts comes to where you turn the light source almost off. At this point, single photons are leaving the source and going theough the aparatus. Since each photon is travelling on its own and has nothing to interfere with, you'd expect that you'd get two thin stripes of impacts representing the photons that managed to go through the two slits.

Wrong! What happens is that if you tally up the impact points over time, you start building up an interference pattern! The only possible explanation is that each photon interferes with itself!

Furthermore, if you monitor a slit to see if a photon goes through a particular slit, the pattern vanishes! This self-interference effect is killed by observation!

How all this occurs is not known. There are a thousand theories out there but I'll describe a few of the mroe plausible ones.

First, the party line is the Copenhagen interpretation drawn up by Niels Bohr and others when quantum physics was being developed in the 20's and 30's. It basically assuems that there are particles that turn into probability waves that go through the slits and make an interference pattern on the final screen. The photon then automagically remanifests itself when the probablility wave collapses. The particle location is purely a probability event - where the probability waves were 'thicker', you havea greater chance of the particle reappearing. This interpretation also says that if you observe a system, the probability waves collapse. The big problem that people ave with this interpretation is that it has this 'observer' involved. What's an observer? If a cat looks at the experiment, does it collapse? What about before the existence of life? Does this theory require the exitence of a God that collapsese the universe's waveforms? Because of the poorly explained observer portion, lots of people are dissatisfied with the Copenhagen interpretation. However, until it is disproven, it is the default explanation because it has so far stood up to all scrutiny.

There's a scad of alternate explanations involving virtual particles, radio waves travelling backwards through time and other weirdness. However, they all share the Copenhagen interpretations weakness - they all add something to the underlying quantum mechanical equations. Those equations never say anything about any sort of waveform collapse so any explanantion that tries to explainit ends up looking like a house with an ugly addition.

Enter the Everett multi-world hypothesis. Everett, back in the 70's, decided to try and look at the the pure equations involved in quantum physics and see what they said, ignoring common sense requirements for waveform collapse. He found that there is actually no reason for the waveforms to collapse. Basically, the photon has two choices - to go through one slit or the other. It doesn't choose - it goes through both and interferes with itself. It hits all points of the final screen. Basically, it's now probabilistically spread out over the entire screen in the pattern of an interference pattern. Now an observer looks at it. Our experience is that we see a flash of light at a point which means that the photon must have collapsed into a single point and all of the other theories assume this as well. What Everett realized is that the human brain is just another quantum mechanical construct like anything else. Basically, as soon as you see that photon spread across the final screen, YOU split into a basically infinite number of different quantum states. Each quantum state sees the photon at a different location but in actuality, the photon is still everywhere.

The popular misconception is that every time there is a quantum mechanical choice, the universe splits into parallel universes. This is a common but incorrect interpretation even among physicists. The universe doesn't split. Instead, all possible things occur simultaneously. According to this model, every possible consequence and outcome that could possibly occur in this universe does occur and at the same time. These alternate realities all coexist with each other in the same time and place but each particular reality can only see itself, giving the illusion that only one thing is going on. Basically, that can happen, does.

This is by far the most elegant interpretation of quantum physics. Unfortunately, by it's own rules, the Everett multiworld hypothesis can never be proven or disproven. By definition, those alternate realities can never 'see' each other so no concievable experiment can confirm or deny this theory.

Shaun Barrett · 2004-04-14 16:03:07

Thanks, SBird, for this very nicely worded account of quantum weirdness.
I do have one small complaint, though. You mentioned that the "two BIG QUESTIONS" of science are the double slit experiment and the relativity/quantum physics incompatibility.
You appear to have totally overlooked the more important and fundamental question involving socks, ballpoint pens and coat hangers!

[Sorry! Feeling a little frivolous today. ]

SBird · 2004-04-14 16:25:21

Well, that's the REALLY BIG question, duh!

Palomar · 2004-04-15 10:30:45

What Everett realized is that the human brain is just another quantum mechanical construct like anything else. Basically, as soon as you see that photon spread across the final screen, YOU split into a basically infinite number of different quantum states. Each quantum state sees the photon at a different location but in actuality, the photon is still everywhere.
The popular misconception is that every time there is a quantum mechanical choice, the universe splits into parallel universes. This is a common but incorrect interpretation even among physicists. The universe doesn't split. Instead, all possible things occur simultaneously. According to this model, every possible consequence and outcome that could possibly occur in this universe does occur and at the same time. These alternate realities all coexist with each other in the same time and place but each particular reality can only see itself, giving the illusion that only one thing is going on. Basically, that can happen, does.
This is by far the most elegant interpretation of quantum physics. Unfortunately, by it's own rules, the Everett multiworld hypothesis can never be proven or disproven. By definition, those alternate realities can never 'see' each other so no concievable experiment can confirm or deny this theory.

*Holy macaroni.

Why does Carlos Castenada come to mind right now? :laugh:

Geez. Um, well he (Mr. Wolf) does go on to say, "Each world appears and disappears -- recombining back into one world -- each time a subatomic particle interacts with something."

Stuff I've read about "psychonautics" seems to fit in here.

You know, it's too bad we can't include little music sound bytes with our posts; the theme from "The Twilight Zone" would be perfect.

--Cindy

::EDIT:: SBird also wrote: "First, I just wanted to add that time dialation by gravity is very well measured. In fact, GPS has to take the faster rate of the atomics clocks on the GPS satellites up in orbit for the system to work properly!"

*Besides the 37-ish (or so) minute time difference between an Earth day and a Marsian Sol, will the lesser gravity on Mars impact upon time keeping too?

SBird · 2004-04-16 11:41:31

Yes, there will be a measureable time dilation effect between here and Mars. However, it will probably be on the order of a few nanoseconds over a persons lifetime so feel free to ignore those "LIVE FOREVER ON MARS" spams that we'll no doubt start to receive...

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#1 2003-12-05 19:44:09

Re: Parallel Universes by F.A. Wolf - ...questions

#2 2003-12-06 07:12:22

Re: Parallel Universes by F.A. Wolf - ...questions

#3 2003-12-06 07:57:17

Re: Parallel Universes by F.A. Wolf - ...questions

#4 2003-12-06 08:00:25

Re: Parallel Universes by F.A. Wolf - ...questions

#5 2003-12-06 10:10:03

Re: Parallel Universes by F.A. Wolf - ...questions

#6 2003-12-06 10:18:10

Re: Parallel Universes by F.A. Wolf - ...questions

#7 2003-12-21 06:39:16

Re: Parallel Universes by F.A. Wolf - ...questions

#8 2003-12-22 12:01:25

Re: Parallel Universes by F.A. Wolf - ...questions

#9 2004-04-14 10:26:49

Re: Parallel Universes by F.A. Wolf - ...questions

#10 2004-04-14 11:32:17

Re: Parallel Universes by F.A. Wolf - ...questions

#11 2004-04-14 16:03:07

Re: Parallel Universes by F.A. Wolf - ...questions

#12 2004-04-14 16:25:21

Re: Parallel Universes by F.A. Wolf - ...questions

#13 2004-04-15 10:30:45

Re: Parallel Universes by F.A. Wolf - ...questions

#14 2004-04-16 11:41:31

Re: Parallel Universes by F.A. Wolf - ...questions

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