# The Grand Speculation?

1. Mar 15, 2011

### ajazz

Assalamualykum

I’m a non-math person, but that doesn’t deter me from being logical and rational who churns out ideas, some of which are stupid, as you don’t have to be stupid to be stupid, I mean you could be as intelligent as Stephen Hawking and still be stupid.

Mr. Hawking acknowledges in his book the grand design that our universe is so finely tuned that it is impossible to have been created accidently but it seems he doesn’t want to believe his own conclusion so he came up with alternate solution.
To eliminate this finely tuned universe conclusion, which imply it has a purpose, he takes help of
M-theory, which predicts about 10^500 universes existing along with ours.by using M-theory
Mr. Hawking has reduced finely tuned universe impossibility to a probability of about 1 in 10^500.

Any gambler out there who wanna bet on this odd?

The problem is M-theory has no scientific evidence to support it, and so to give it legitimacy Mr. Hawking
Uses Feynman multiple histories which states that a particle traveling from point A to point B takes all the possible paths and hence has infinite number of histories.
Since creation of our universe was a quantum event it has multiple histories about 10^500 and we happen to in one whose laws allow us to exist, this is what Mr. Hawking says.

How scientific, logical and rational is this?

Suppose we as observer who is outside the universe and have a button, when we press this button
Our universe freezes i.e. it stops expanding.
Now we fire a particle and when it reaches point B we press our pause button. According to Feynman our particle has taken all the available paths. Now the smallest meaningful length is a Planck-length
Let’s assume that each path that our particle has taken is one Planck-length in width and the next path will be another path one Planck-length wide. We count all the paths and assign it letter Z.
Now Z is the total number of paths that our particle has taken.
In his book Mr. Hawking says that we must take top down approach i.e. from present time we must go back in time towards the creation of our universe. We will do the same we go back in time and conduct our experiment again and pause our universe and count the number of paths our particle has taken and assign it letter Y.

We will find that Y is smaller than Z because as we go back in time our universe is becoming smaller and smaller.as we continue to go back in time we reach a point where our universe is only one Planck-length in size.

Now if we conduct our experiment we find that there is only ONE path that our particle can take and therefore our universe has single history, if we use the same logic as Mr. hawking’s

At this point Feynman multiple histories break down and so does Mr. Hawking’s idea that our universe has multiple histories.
does it?

In his book Mr. Hawking says:
“In the early universe—when the universe was small enough to be governed by both general relativity and quantum theory—there were effectively four dimensions of space and none of time.”

Now as we know that general relativity breaks down at quantum level, right?

And creation of our universe is a quantum event as told to us by Mr. hawking.

This means that our universe was in a state previous to the state that Mr. hawking described as small enough with four dimension of space and none of time, this means our universe existed in whatever form previous to the state when it was big enough to be governed by both general relativity and quantum theory but no time.

This in turn means there was a history or past to our universe when it was big enough with four dimension of space and none of time.

But please can someone explain to me how can we have history or past without time?

2. Mar 15, 2011

### Forestman

I can see why you would be skeptical of other universes and things of that nature. You are right though, there is no evidence supporting these things. Personally I do believe in other universes and M theory, but that is just me. It might turn out that you are right, and I am wrong. I am sure that many others here would not like your point of view since it goes against the current line of thinking about the universe, but I think that it is always good to have another point of view. Whatever is true is true, and what we say won't change that. Anyway, you expressed yourself very well with what you wrote.

One thing that might change your mind about Feymans sum over histories is the double slit experiment. I am sure that others are tired of me posting this video, but I think that it might change your mind on some things. Anyway, give it a watch.

Last edited by a moderator: Sep 25, 2014
3. Mar 16, 2011

### Chalnoth

While it is reasonable to be skeptical about any specific multiverse proposal, the idea of a multiverse in general is extremely robust, and you arrive at the result of some form of multiverse from a great number of directions. For example:

1. There is a limit to how far we can see. It is completely unreasonable to claim that the universe just ends right at the limit of what we can see: the natural expectation is that it extends for some significant distance beyond our vision.
2. If we believe that there was some sort of physical process that got our visible universe started, then it is completely unreasonable to claim that that had to be a one-off event. The natural expectation for physical processes is that they occur over and over again, given the right conditions.
3. Within high-energy physics, there are certain quantities that, according to our best experimentally-tested models, take the values they do by an accident of past history. So if the universe is big or there were many events that started other regions of space-time off elsewhere, then we expect these parameters to take on different values, leading to different low-energy physics.
4. Within physics, there are a number of quantities for which we do not have a good model for how they came about, but the values they do take are very strange on the surface. Many of these make perfect sense, however, if the universe is very large and these parameters are allowed to take values as a result of accidents of past history.

So to me, a multiverse is basically inescapable, and it would really require strong evidence that it wasn't the case not to believe it is the most likely.

4. Mar 16, 2011

### Chronos

I am skeptical of M-theory because no compelling evidence of other universes has been produced. Asserting our universe is the way it is because there are a gazillion other unseen universes is not a satisfying explanation, IMO. Most of our universe is explicable. Godel's incompleteness theorem suggests there will always be certain aspects of our universe that resist explanation.

5. Mar 17, 2011

### ajazz

Assalamualykum

Can you be more specific when you say “I can see why you would be skeptical of other universes and things of that nature"

As far as big bang, inflation, multi-dimensions, and yes universe created out of nothing, goes
I do not disagree with because they do not go against my belief system.

But yes, multiple histories (especially when it is we who decide which history) and naturally occurring physical laws creating our universe out of nothing, I do not agree with.

When Mr. hawking says” when the universe was small enough to be governed by both general relativity and quantum theory—there were effectively four dimensions of space and none of time”

My question is can any law or physical process, operate without time?

If the answer is no then, general relativity and quantum theory which operate without time are really supernatural and therefore creation of our universe was a supernatural event.

.

Last edited: Mar 17, 2011
6. Mar 17, 2011

### Chalnoth

You're twisting the word supernatural to mean something that basically nobody considers it to mean.

7. Mar 17, 2011

### Staff: Mentor

Am I correct in my understanding that the Big Bang doesn't mean that there was "nothing" before that and our universe came from that?

8. Mar 18, 2011

### Chalnoth

Yes. The big bang theory only describes how the universe behaved after a certain point. Before that point, the predictions become nonsensical and nobody takes the theory seriously.

9. Mar 18, 2011

### skydivephil

One thing I think we can state is that multiple universes do not depend on M theory. There are many ideas which imply a multiverse, not just from M theory.
Eternal inflation also implies a multiverse
You may want to read this:
http://arxiv.org/abs/hep-th/0702178

10. Mar 18, 2011

### skydivephil

I hope you will contunue to investiage not just scientific findings but scientific methdology. A statement such as :
"I do not disagree with because they do not go against my belief system." doesnt really have a place. You might argue there is no evidence or the evidence that does exist is questionable or there is lack of mathematical coinsistency, but your prior beliefs are not relevant. If scientists simply employed their prior beliefs i doubt we would make a lot of progress.

11. Mar 19, 2011

### Chronos

What role does belief play in the fact there is no credible evidence of other 'universes'? My belief system is simple, empirical evidence - which currently suggests we reside in a finite universe of finite age.

12. Mar 19, 2011

### ajazz

Assalamualykum

I have some issues with Mr. Feynman’s sum over histories, hope you are able to clear it for me but before that let me quote how Mr. Hawking introduces him in his book:

“Richard (Dick) Feynman, a colorful character who worked at the California Institute of Technology and played the bongo drums at a strip joint down the road.”

So let’s go bongo.

We will test the histories at present.

When a particle travels from point A to B it takes all the available paths simultaneously.
For simplicity let’s choose only four paths A, B, C, D,
A which is 186000 miles and B is around sun and back
C goes around Sirius and comes back while D the longest touches the edge of our universe.

Actually I have not made this up Mr. Hawking himself says this in his book:

“In the double-slit experiment Feynman’s ideas mean the particles take paths that go through only
one slit or only the other; paths that thread through the first slit, back out through the second slit,
and then through the first again; paths that visit the restaurant that serves that great curried shrimp,
and then circle Jupiter a few times before heading home; even paths that go across the universe
and back.”

Our particle travels at the speed of light.

Particle-multiple-me takes 1 sec to reach its destination taking path A, but for particle-multiple-me taking path B it must go faster than the speed of light to catch up with path A, because they must arrive at the destination same time and for path C it must increase further.
And poor particle-multiple-me taking path D must travel at about 180 billion times the speed of light!

You say no-no the particle travel at the same speed.

If so then particle at A which is about to hit the destination stops and wait because path B is longer than
Path A, particle at B is about to hit the destination but both have to wait till particle at C arrives.

Situation is worst for poor particle at path D no matter how hard it tries, the edge of our universe is playing hardball with him (her?) and saying catch me if you can , you guessed it right our universe is expanding at a tremendous speed and the three idiots do not realize their wait may be eternal!

My guess is the idea of multiple histories was conceived during uncontrolled aggressive banging of the bongos caused due to over stimulation of visual cortex.

Had this idea been conceived by uneducated-me who hangs by thin cord of his belief system
It would have been understandable.

May be its time you change your mind about Feynman's sum over histories.

.

Last edited by a moderator: Sep 25, 2014
13. Mar 19, 2011

### Chalnoth

The sum over histories has been proven to be mathematically identical to other approaches to quantum mechanics.

14. Mar 19, 2011

### SW VandeCarr

From the QM view, the particle is already "everywhere" with some non zero probability, but is in a small volume with a high probability. The mean apparent path to a detector is the shortest one (on a geodesic). This is the only path that is observed (or at least observed with very high probability) . All other paths "vanish". Also the if the particle has rest mass, it doesn't travel at the speed of light. I think Feynman's examples concerned electrons.

Last edited: Mar 19, 2011
15. Mar 19, 2011

### marcus

Your greeting sounds like the Hebrew for "Peace be with you." (shalom aleichem)
But in a related language. I'm curious to know what language.

I don't think one should take Hawking's book seriously. From the excerpts I've seen, it seems to have been written to make money by exploiting a naive sector of the public.

As for the Feynman path integral I would advise you not rely on Hawking's pop-sci account of it.

AFAICS the sooner "The Grand Design" goes into everybody's recycle bin and is forgotten, the better off we'll be.

It is not standard mainstream cosmology as done by professional working cosmologists and such as we normally try to discuss here in Cosmo forum. Cosmology is an observational science (fitting data to model) not speculation or pop-philosopy.

If this thread if going to be a discussion of Hawking's book, I'd say it does not belong in cosmology but it's not up to me--- the mentors decide where threads belong. As a wild guess, maybe in General Discussion, Philosophy, Social Science, or possibly in the Book Review subforum.
https://www.physicsforums.com/forumdisplay.php?f=21
It's hard to say where.

Does anybody know of an introduction to Cosmology that Ajazz could read that would get him/her started off on the right foot? Something that presents what the field is really about and what the current developments are?

Last edited: Mar 19, 2011
16. Mar 19, 2011

### Chalnoth

It's Arabic. Means the same thing. I only know of this because of the horrifying Ahmed Sharif story.

17. Mar 20, 2011

### ajazz

Assalamualykum

yes you are right, but i am not Arab, i am Indian.

18. Mar 20, 2011

### ajazz

Assalamualykum
The sum over histories does not predict it only gives probability therefore it is bound to agree with other approaches.

The sum over histories makes many comprises therefore it does not predict but can only give probability.

For example not all the paths are included in the calculation simply because it is impossible.

Only some probable paths are taken into account (Feynman’s diagrams).
Now if Feynman diagrams are added, you get electron with infinite charge and mass.
This is nonsense, as you see sum over histories give nonsensical result.

To give some sense another compromise is made known as renormalization; these manipulations reduce the infinite mass and charge of electron to finite value.

Now please forgive me for quoting Mr. Hawking, he is my argument by authority and no, this is not a review of the grand design rather clash of ideas.

Rather than choosing your history you better choose you belief system.

So Mr. Hawking says:

“These manipulations might sound like the sort of things that get you a flunking grade on a school math exam, and renormalization is indeed, as it sounds, mathematically dubious”

In short sum over histories is dubious.

You should know that all mathematical equations do not correspond to physical reality.

General relativity and newton’s laws are derived from physical reality that is why they work.

Unlike some other theories floating around which are derived from imaginations example M-theory which is nothing but string theory with new clothes (personal belief system?).

What these theories are trying to do is convert imagination into physical reality which is bound to fail if the imagination is not logical and rational.

I have a brilliant idea, that there exists a triangle with four sides.

Now I convert this idea to mathematical equation by adding lots of variables and what not but my equation does not work as I want it to work so I add some constant and make it work.

Now even though I made my equation work you can be pretty sure it will not get translated into physical reality because it is illogical and irrational.

Therefore in my HTWO ( humble tumble whatever opinion) logic and rationality takes precedence over empirical evidence, if it is making mincemeat of logic and rationality, please do not take me wrong, I’m not talking about blind faith here.

.

19. Mar 20, 2011

### ajazz

Hawking occupies the Lucasian chair of applied mathematics and physics at Cambridge University. The chair's second occupant was Isaac Newton, "though it wasn't electronically operated in his time,"

"Stephen Hawking may not be as brilliant as Albert Einstein. But the public's imagination links the two physicists as symbolizing the mind-boggling phenomenon of scientific genius. Einstein with his nimbus of white hair who couldn't walk from his office to his home without getting lost. Hawking as the ironic tragedy."

http://goo.gl/KQXxU

.

20. Mar 20, 2011

### Chalnoth

The thing I don't think you're getting here is that the only predictions that quantum mechanics ever provides are probabilistic predictions.

That's not true. It is quite mathematically possible to include all paths, provided you make certain simplifying assumptions, such as that the only matter in the universe is the matter involved in the reaction you're investigating (usually this is a good approximation, because the reactions we consider aren't very much affected by other nearby matter, most of the time).

That's just because you get infinities assuming you can take the sums to infinite energies, which nobody believes is accurate. Instead, what is done is we cut off the sums at some finite energy, wrap the rest of the sums into a set of parameters that can be measured experimentally, and then prove that the result we get is independent of the cutoff energy we use.

Obviously, we'd ideally want to be able to have a theory which describes what goes on at these high energies. But in any event it isn't a problem of the "sum over histories", but rather of our ignorance of the behavior of matter at very high energies.