Universe or Multiverse?

[zaangalewa]

What's your consensus?

Does Gravity interact with matter, regardless of it's dimensional origin? If so, is Gravity the answer to Dark Matter...?

Will we ever even be able to peer deep enough into the world of the Very Small to test these things (perhaps via String Theory)?

I'd love to hear everyone's theories on the matter.

No Politics Please.

How anyone can say anything other than unsure is beyond me. We just don't know.

But we know nothing on different levels of competence. Scientists should know how to build a cathedral of knowledge. If we don't know: On what reasons do we not know? Are there ways? Are there no ways?

Scientists are looking for information and ploughing forwards with their ideas. However, on the multiple universe thing, I'd say we so far away from knowing that it's ridiculous to even bother.

A second ago a universe was where you was. What is now there?

Still here. Nothing has changed much from a second ago.

Astonishing idea.

 

[Vikrant]

I just wanted to expand on potential a bit as it relates to a topic in string theory called landscape and possibly multiverse as well. As you pointed out, every object has potential. This potential can be plotted on a multi-dimensional graph. The object's initial state or position on the graph is called minima. The object needs additional energy to move to the next state. If it does not find that additional energy then it can get stuck in a given minima and fail to move to the next state. Similarly our universe too can get stuck at a given minima. The different versions of string theory simply describe different sates of the universe. We simply have not yet theorized a version of string theory which describes the current state of our universe. These different states of the universe have very different properties. For example in one state, the space can be three dimensional and in another state, space can be of more dimensions (up to 10 dimensions). This is where string theory start to converge with the idea of multiverses each with their own unique properties.

I haven't heard of the local minimum aspect in multiverses. I have read that shortly after the big bang there were possibilities of different phases, similar to the solid state phases of carbon (graphite, diamond, etc). After a point when the temperature of the universe dropped to a certain point, the laws of physics were frozen into it's current form (or phase). That is the same concept as annealing some types of metals: a hot metal is cooled in a way to lock in a particular phase. It now makes sense, the local minima mathematically represent the different phases our universe can (could) be in. As you say, since the universe is much cooler now, we are stuck in our current local minimum.

As far as the dimensionality of space-time, if there were more or less than 3 space-like dimensions, the inverse square law would no longer be valid in gravity or EM theory.

One interesting thing about string theory is that all 10 dimensions are closed – circular. Space and time are huge circles encompassing the closed universe. The remaining dimensions are tiny circles;10^20 times smaller than the diameter of a proton. It would be interesting to see what a universe would be like where some of the large dimension circles are interchanged with smaller dimensional circles. I assume that what you meant by different states of the universe.

By state, I simply mean different phases of the universe as described by different versions of the string theory. Multiverse is an independent idea that was conceived way before string theory. The fact that string theory describes possibilities of different phases of universe with their own unique properties serves as a basis to extend this idea to imagine multiple universes each with their own distinct characteristics. That is what I was alluding to. Besides that, there are indeed versions of string theory that call for fascinating ideas like parallel universe, etc.

At the moment, I do not think there is a version of string theory that has less than 10 dimensions. So there is no need to worry about contradicting Inverse Square Law which makes sense to us from 3D space and 1D time.

 

[MaryL]

Theoretical physics says that time is artificial and everything happens at once. And matter is made out of convoluted nothing. Like a Buddhist dream. Perception is everything. And nothing.

 

[Vikrant]

I want to expand on the state (phase) of the universe a bit further as it is a fundamental challenge in constructing a string theory that describes our universe as we know it. However, in order to do that, we have to understand the concept of minima within the context of string theory. The discovery that our universe is expanding rapidly has changed the way we traditionally thought about our universe. Further you look in the universe, faster the expansion is. Then the question arises, what is holding us intact? The best explanation for this to date is Einstein's cosmological constant. According to our modern experiments and calculations, cosmological constant denoted by Einstein in his equation accounts for more than 70% of the energy in the universe. Rest is made up of ordinary matter and dark energy. This cosmological constant is the local minimum of the current state of our universe. Obviously, different versions of string theories have different values for local minimum, maxima and saddle points. There are versions of string theory where minimum is negative and zero; this has dire consequence as you will see later in the post. As of today, we have not come up with a version of string theory where minimum's value is cosmological constant. In quantum theory, a field moves away from the local minimum if energy fluctuates. Let us do a thought experiment and imagine that this field is encapsulated inside a bubble. Occasionally, a given field in the bubble will fluctuate to another minimum of the potential. If the new minimum has lower potential energy than the original minimum then the bubble will have lower potential energy. In order to maintain the surface tension of the bubble, certain amount of energy is needed.

PE = - Ar^3 + Br^2

(PE = Potential Energy, A = positive constant, B = positive constant, r = radius of the bubble)

If r > B/A then this results in negative. A such bubble will start to expand. This happens because excess PE starts to transfer towards the surface of the bubble as KE. This initiates a domino effect resulting in rapid expansion of the surface of the bubble eventually reaching the speed of light. As this surface expands, it destroys everything in its way -- the ultimate doomsday. This is how our universe changes its state. The new state of the universe can and most likely will have totally different properties such as type and number of elements, etc.

If you are worried about the bubble, don't. We will be dead even before we know what hit us. However, this doomsday is inevitable as you can see there are versions of string theory that have zero or negative value for cosmological constant that substitutes for minimum.

 

[Vikrant]

Please, by all means, keep going. I'm feeling a bit like Johnny-5 this morning and I'm hungry for more input!

Documentaries often leave something to be desired. They are like books on various aspects of science. A science book can be chock full of advanced mathematics or none at all. I read that some publishers will not accept a book for general readership if it has even only one simple mathematical formula in it.

There is a lot of very interesting aspects to the various advanced topics in science that any high school grad can understand if only a little math is involved, but nobody publishes at that level.

This is something I have only seen once somewhere. It is very simple, but it gave a much deeper understanding of Relativity. Bare with me.

The Pythagorean theorem to find the distance along a diagonal is:

D = sqrt( x^2 + y ^2)

Suppose I told you the the dimensions were x =3 and y = 4. What is D. You would say 5? I fooled you because x is in inches and y is in centimeters. In order to solve it now, you need to have a conversion factor for the units of measurement. It would be

D = sqrt( (2 in)^2 + ( 3 cm * (1 in / 2.54 cm))^2 )

To simplify it lets just rename the conversion factor:

c = (1 in / 2.54 cm)

The Pyth theorem for that case is now

D^2 = sqrt( x^2 + (y*c)^2 )

That version is the distance between two points


Suppose we are told that time is a fourth dimension. The Pyth theorem for that case is

S^2 = sqrt( x^2 + y^2+ + z^2 + t^2 ), ... where t is time.

Oops I forgot we need a conversion factor. Suppose x, y, and z are in miles, the conversion factor for time must be some constant, c, in units of distance/time. Those units are a velocity which happens to be 186000 miles/hour, the speed of light.

So it turns out that when we think of the velocity of light as the maximum that any object can travel, we are missing the very important fact that it is really a conversion factor to make the Pyth theorm work. However that's not quite all of it. The conversion is also multiplied by an imaginary number i, where i^2 = -1.

That gives an unusual distinction between space and time. So the result is

S = sqrt( x^2 + y^2 + z^2 - (t*c)^2 ) ... the t term has a minus sign.

This version is the distance between two events.

The thing that struck me about that analysis is that the velocity of light is just a conversion factor. And it was shown that anything with a zero mass (photon) is obligated to travel at the speed of that conversion factor. Variable S is no longer a distance because it involves time. S is an event (a point in space and time), separated by another event.

Maybe tomorrow I will show why I think quantum entanglement isn't as bizarre as some might think.

It seems like you are defining events using Galilean Relativity and Pyth Theo. The event you are describing is called Space-Like Event and is depicted as r = SqRt(-S^2) = SqRt(x^2 - t^2).

There are two other types of events: Time-Like Event and Light-Like Event.

Time-Like event which is the most basic type of event is defined as r = SqRt(S^2) = SqRt(t^2 - x^2).

So given a frame of reference O and a Time-Like Event E1 and a Space-Like Event E3, you can form a Light-Like Event E2. See the diagram below:

This is called Light-Cone. O is the point which separates past from the future. I have written about it in more detail in one of the treads that was started a while back on the subject of Time Dilation.

 

[Wuwei]

PE = - Ar^3 + Br^2
etc.

I have not seen that explanation before. It seems that could also be an underlying concept of the start and growth of the big bang including inflation.

 

[Wuwei]

There is an interesting concept in a book by John Gribbin, "Schrodinger's Kittens and the Search for Reality." He describes work by Cramer and Chu.

There are two solutions of the classical EM equations for emission of radiation. There is advanced and retarded radiation. The advanced radiation is moving backwards in time to the emitter and the retarded solution is the usual radiation outward and forward in time from the emitter.

Similarly there are two solutions to relativistic QM, forward and backward in time. In calculations everyone throws away the backward-time solution because it doesn't make sense. However the photon traveling at the speed of light has no sense of space and time, or future and past.

From our perspective a photon is emitted from an atom and strikes another atom later. From the photon's perspective it leaves the first atom and strikes the other atom simultaneously, ie in zero time.

This can also be seen as a limiting case of the Lorentz contraction. The faster one goes the shorter the distance from one object to another. At a the speed of light the Lorentz contraction shrinks space (and therefore time) to zero. So a photon sees the whole universe as one infinitesimally thin sheet.

For those who know QM, the probability of a particle location is given by the complex wave function multiplied by it's complex conjugate. That gives a real observable probability. The complex conjugate simply has the sign of the imaginary part negated. That negation is a backward-time solution. So the act of computing the probability of a particle location is using the backward and forward time solution whether you like it or not.

So as far as "spooky action at a distance" (A. Einstein), that is only from our perspective, not the perspective of a photon. So it makes sense that entangled photons really are locally entangled, but we people can't directly see it that way. To us they are globally entangled, which is "spooky".

 

[Unkotare]

Theoretical physics says that time is artificial and everything happens at once. And matter is made out of convoluted nothing. .....

No, it doesn't.

 

[zaangalewa]

Theoretical physics says that time is artificial and everything happens at once. ...

The chicken crosses the road because never a chicken collidates with cars of the past and future? Not really, isn't it? So theoretically past, present and future are real.

When Einstein said once "time is only an illusion" he wrote this in a letter of condelence. Indeed is everything always only a kind of artificial illusion - because we simulate always the reality all around. What we see is a bio-psychological result of electrochemical impluses on membranes of cells. Ask Immanuel Kant. This 2D-structure allows us to see a 3D-world. Pain is for example nothing else than only such a form of "artifical illusion" - but one of the most mighty realities the same time. Who feels no pain is not able to survive. Our perception tells us something about the world all around. If it is true what we think then we know.

 

[HUGGY]

What if several black holes merged and their collective nature was far more reaching than what they now present. This new super black hole may start swallowing up matter at far greater distances and even reach out to gather even more black holes until it could absorb whole galaxies.

What then? Is it possible that there is enough "negative" energy and power within it to reverse the expansion of the known universe and cause the universe to implode?

 

[Unkotare]

What if several black holes merged and their collective nature was far more reaching than what they now present. This new super black hole may start swallowing up matter at far greater distances and even reach out to gather even more black holes until it could absorb whole galaxies.

What then? Is it possible that there is enough "negative" energy and power within it to reverse the expansion of the known universe and cause the universe to implode?

No

 

[HUGGY]

What if several black holes merged and their collective nature was far more reaching than what they now present. This new super black hole may start swallowing up matter at far greater distances and even reach out to gather even more black holes until it could absorb whole galaxies.

What then? Is it possible that there is enough "negative" energy and power within it to reverse the expansion of the known universe and cause the universe to implode?

No

Whew!

 

[Vikrant]

PE = - Ar^3 + Br^2
etc.

I have not seen that explanation before. It seems that could also be an underlying concept of the start and growth of the big bang including inflation.

I often browse Cornell University's online library on my spare time looking for interesting stuff to read.
arXiv.org e-Print archive

Not too long ago I came across a paper written by Ashoke Sen called Riding Gravity Away from Doomsday. He is a well known String theorist. He was awarded Fundamental Physics Prize not too long ago. The forumula you quoted is from his paper. I think the formula itself seems to have its origin in Quantum Field Theory, more specifically Phase Transition.
https://arxiv.org/pdf/1503.08130.pdf

 

[rdean]

The problem with all of this is it's nothing but pure conjecture. I thought science was supposed to be about observation and measurement.

This is just a bunch of physicists talking out of their ass.

My theory is that tiny green monkey too small to ever observe or measure fly out of God's ass every time he farts. The tiny monkeys are the substance that holds the universe together. Prove me wrong.

Sadly, my statement is subject to just as much "science" and experimentation as the questions posed above. This is why physics has largely become irrelevant.

There was no way to prove that the Sun didn't rotate around the Earth...

....Until it was proven.

Black holes were known to exist. Until it was proven. It's called "physics".

 

[Vikrant]

There is an interesting concept in a book by John Gribbin, "Schrodinger's Kittens and the Search for Reality." He describes work by Cramer and Chu.

There are two solutions of the classical EM equations for emission of radiation. There is advanced and retarded radiation. The advanced radiation is moving backwards in time to the emitter and the retarded solution is the usual radiation outward and forward in time from the emitter.

Similarly there are two solutions to relativistic QM, forward and backward in time. In calculations everyone throws away the backward-time solution because it doesn't make sense. However the photon traveling at the speed of light has no sense of space and time, or future and past.

From our perspective a photon is emitted from an atom and strikes another atom later. From the photon's perspective it leaves the first atom and strikes the other atom simultaneously, ie in zero time.

This can also be seen as a limiting case of the Lorentz contraction. The faster one goes the shorter the distance from one object to another. At a the speed of light the Lorentz contraction shrinks space (and therefore time) to zero. So a photon sees the whole universe as one infinitesimally thin sheet.

For those who know QM, the probability of a particle location is given by the complex wave function multiplied by it's complex conjugate. That gives a real observable probability. The complex conjugate simply has the sign of the imaginary part negated. That negation is a backward-time solution. So the act of computing the probability of a particle location is using the backward and forward time solution whether you like it or not.

So as far as "spooky action at a distance" (A. Einstein), that is only from our perspective, not the perspective of a photon. So it makes sense that entangled photons really are locally entangled, but we people can't directly see it that way. To us they are globally entangled, which is "spooky".

I agree. From the perspective of a photon travelling at the speed of light, there is no future or past. It finds itself at the point where vertices of future Light-Cone and past Light-Cone meet. If you go faster than the speed of light, you will cross O and find yourself in past. See the Light-Cone diagram above.

However, as far as the entangled particles are concerned, there is no photon or any other particle that we know of acting as a carrier of information between the entangled particles. So we cannot explain this using classical mechanics used in Theory of General Relativity. Actually, this brings us to the limitation of Theory of General Relativity.

 

[MaryL]

Theoretical physics says that time is artificial and everything happens at once. And matter is made out of convoluted nothing. .....

No, it doesn't.

After close examination, science proves your head is a perfect vacuum.

 

[Wuwei]

I often browse Cornell University's online library on my spare time looking for interesting stuff to read.
arXiv.org e-Print archive

Not too long ago I came across a paper written by Ashoke Sen called Riding Gravity Away from Doomsday. He is a well known String theorist. He was awarded Fundamental Physics Prize not too long ago. The forumula you quoted is from his paper. I think the formula itself seems to have its origin in Quantum Field Theory, more specifically Phase Transition.
https://arxiv.org/pdf/1503.08130.pdf

Very interesting paper. In an earlier life I was involved in a study of bubble nucleation in super-heated liquids. Microscopic bubbles continuously spontaneously grow and collapse. The liquid can remain stable if the bubbles are small. As the liquid gets hotter the internal pressure of an incipient bubble will approach the size where it will no longer collapse, but grow violently.

When it comes to the universe it seems that gravity would be the surface tension and the cosmological constant would be the pressure. I forgot the theory but my feeling is that PE = - Ar^3 + Br^2 could have come from the theory of bubble nucleation in super-heated liquids.

 

[Unkotare]

There is an interesting concept in a book by John Gribbin, "Schrodinger's Kittens and the Search for Reality." He describes work by Cramer and Chu.

There are two solutions of the classical EM equations for emission of radiation. There is advanced and retarded radiation. The advanced radiation is moving backwards in time to the emitter and the retarded solution is the usual radiation outward and forward in time from the emitter.

Similarly there are two solutions to relativistic QM, forward and backward in time. In calculations everyone throws away the backward-time solution because it doesn't make sense. However the photon traveling at the speed of light has no sense of space and time, or future and past.

From our perspective a photon is emitted from an atom and strikes another atom later. From the photon's perspective it leaves the first atom and strikes the other atom simultaneously, ie in zero time.

This can also be seen as a limiting case of the Lorentz contraction. The faster one goes the shorter the distance from one object to another. At a the speed of light the Lorentz contraction shrinks space (and therefore time) to zero. So a photon sees the whole universe as one infinitesimally thin sheet.

For those who know QM, the probability of a particle location is given by the complex wave function multiplied by it's complex conjugate. That gives a real observable probability. The complex conjugate simply has the sign of the imaginary part negated. That negation is a backward-time solution. So the act of computing the probability of a particle location is using the backward and forward time solution whether you like it or not.

So as far as "spooky action at a distance" (A. Einstein), that is only from our perspective, not the perspective of a photon. So it makes sense that entangled photons really are locally entangled, but we people can't directly see it that way. To us they are globally entangled, which is "spooky".

I agree. From the perspective of a photon travelling at the speed of light, there is no future or past. It finds itself at the point where vertices of future Light-Cone and past Light-Cone meet. If you go faster than the speed of light, you will cross O and find yourself in past. See the Light-Cone diagram above.

However, as far as the entangled particles are concerned, there is no photon or any other particle that we know of acting as a carrier of information between the entangled particles. So we cannot explain this using classical mechanics used in Theory of General Relativity. Actually, this brings us to the limitation of Theory of General Relativity.

Zeno's Paradox of the Arrow

 

[Vikrant]

I often browse Cornell University's online library on my spare time looking for interesting stuff to read.
arXiv.org e-Print archive

Not too long ago I came across a paper written by Ashoke Sen called Riding Gravity Away from Doomsday. He is a well known String theorist. He was awarded Fundamental Physics Prize not too long ago. The forumula you quoted is from his paper. I think the formula itself seems to have its origin in Quantum Field Theory, more specifically Phase Transition.
https://arxiv.org/pdf/1503.08130.pdf

Very interesting paper. In an earlier life I was involved in a study of bubble nucleation in super-heated liquids. Microscopic bubbles continuously spontaneously grow and collapse. The liquid can remain stable if the bubbles are small. As the liquid gets hotter the internal pressure of an incipient bubble will approach the size where it will no longer collapse, but grow violently.

When it comes to the universe it seems that gravity would be the surface tension and the cosmological constant would be the pressure. I forgot the theory but my feeling is that PE = - Ar^3 + Br^2 could have come from the theory of bubble nucleation in super-heated liquids.

It seems like bubble nucleation that transitions False Vacuum to True Vacuum became a basis for the doomsday idea.
http://www.sns.ias.edu/pitp2/2011files/PhysRevD.21.3305.pdf

Idea of Decay of False Vacuum seems to be based on First Order Phase Transition.
http://www2.chem.uic.edu/rjgordon/teaching/chem342/lect26_35.pdf

Those two links seem to contain enough information to derive:
PE = - Ar^3 + Br^2

 

[Wuwei]

It seems like bubble nucleation that transitions False Vacuum to True Vacuum became a basis for the doomsday idea.
http://www.sns.ias.edu/pitp2/2011files/PhysRevD.21.3305.pdf

Idea of Decay of False Vacuum seems to be based on First Order Phase Transition.
http://www2.chem.uic.edu/rjgordon/teaching/chem342/lect26_35.pdf

Those two links seem to contain enough information to derive:
PE = - Ar^3 + Br^2

It's amazing that you found these articles.
On the first page of the first reference the authors do refer to thermodynamic nucleation processes:

The decay of the false vacuum is very much like the nucleation processes associated with first-order phase transitions in statistical mechanics. ' The decay is initiated by the materialization of a bubble of true vacuum within the false vacuum.​

The first few pages of the second reference refers to first order phase transitions.

Of course I didn't actually read the rest of the articles. I have been away from that for too long. Each would take me over a half a year to understand.