Which is why we need to cast aside the idea of such a singularity, or at least be open to redefining the term so far as it relates to the BB, much like Roger Penrose has done in his conformal cyclic cosmology.
The Universe has boundary?
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Which is why we need to cast aside the idea of such a singularity, or at least be open to redefining the term so far as it relates to the BB, much like Roger Penrose has done in his conformal cyclic cosmology.
There is one correction, you can't have infinite energy from microscopic point-singularity, that's impossible, even the universe is not eternal, if it was it would require infinite amounts of energy. Like someone already said the strongest proofs are towards the BB theory, so it was obvious there was some big bang. Other questions are matter of opinions, since they are all unprovable like multiverses. I also have some hypothesis, but it's unprovable, this is why I consider this is not for this forum, since it is a speculation.
Everyone has rights to their own opinions, but I'm not sure if moderators allow that here on science forums.
You will find a brief outline here, as well as the name of the book Penrose has written on the subject.
Note that this is still a somewhat controversial cosmology.
I believe that one could say that the universe has a net energy of zero, whether it is infinite or not.
I generally think of it more in terms of boundless physicality.
actually you are right about this.
even if this was the case, what you are describing only happens during the distant light has already traveled. like i said, and you never addressed this, the untraveled distant expands before lights gets there. this automatically increases travel time.
i don't see any confusion/contradiction/paradox in today's general consesus whatsoever. from wiki:
http://en.wikipedia.org/wiki/Observable_universe
The age of the universe is about 13.75 billion years, but due to the expansion of space we are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distance at the present time) than a static 13.75 billion light-years distance.[2] The diameter of the observable universe is estimated to be about 28 billion parsecs (93 billion light-years),[3] putting the edge of the observable universe at about 46–47 billion light-years away.
what this means is that the light reaching us today emitted from a place that is much closer to us than 14 B light year. however, since space expanded as it traveled, it took this light 14 B years to get to us. and at the present, this place is actually 46-47 B light years away. clearly the expansion of space increases light's travel time.
and your theory on gravitational effect is intersting but very weak and is purely speculation. and i don't think any scientists would back that up.
i think it was Hawkings and anther scientists who claimed that the net energy in the universe is 0 with gravitational energy being "negative energy" and everything else being positive energy.
this is in agreement with the latest theory that states that the universe came from nothing. a very small amount of energy was needed to "jump start" the Big Bang and it happened due to quantum fluctuations.
The idea of a zero-energy universe, together with inflation, suggests that all one needs is just a tiny bit of energy to get the whole thing started (that is, a tiny volume of energy in which inflation can begin). The universe then experiences inflationary expansion, but without creating net energy.
What produced the energy before inflation? This is perhaps the ultimate question. As crazy as it might seem, the energy may have come out of nothing! The meaning of "nothing" is somewhat ambiguous here. It might be the vacuum in some pre-existing space and time, or it could be nothing at all – that is, all concepts of space and time were created with the universe itself.
Quantum theory, and specifically Heisenberg’s uncertainty principle, provide a natural explanation for how that energy may have come out of nothing. Throughout the universe, particles and antiparticles spontaneously form and quickly annihilate each other without violating the law of energy conservation. These spontaneous births and deaths of so-called "virtual particle" pairs are known as "quantum fluctuations." Indeed, laboratory experiments have proven that quantum fluctuations occur everywhere, all the time. Virtual particle pairs (such as electrons and positrons) directly affect the energy levels of atoms, and the predicted energy levels disagree with the experimentally measured levels unless quantum fluctuations are taken into account.
http://www.astrosociety.org/pubs/mercury/31_02/nothing.html
This talk will be right up your alley, if you haven't seen it already:
'A Universe From Nothing' by Lawrence Krauss
'A Universe From Nothing' by Lawrence Krauss
First the Wiki article you quote above assumes the basic and functional foundation provided by the BB theory as already proven, and then extrapolates upon the assumptions that support the BB. i.e. if the universe started with the BB and is still expanding.., the visible universe is .....
That article already assumes the facts that I thought were being discussed here. The BB has been at the foundation of cosmology for sometime now, but is beginning to be challenged by other models. Actually it has always been being challenged, it just had a majority consensus in support, in the past, where today that consensus is being challenged more effectively.
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Second I am not sure where you get the idea that I presented "my" gravity model anywhere. All I was doing in introducing the globalization of gravity into the discussion was pointing out that GR describes gravity such that it curves space near a large mass and theoretically outward from that mass to infinity. This is not my theory. It is GR and the Newtonian view for that matter. It is just that we are only able to detect that curvature close to a large mass where the curvature is large enough to be greater than experimental error with our current technology.
I did speculate on the interaction of space and mass/matter as being fundamentally an inertial relationship. I have not seen anyone else speak to this directly. However it is a direct result of the Lense-Thirring effect which was first published.., I think in 1917 and earlier in correspondence with Einstein beginning, shortly after his publication of GR in 1915. It is an aspect and direct result of the curvature of space. When the Lense-Thirring effect and Newton's 3rd Law of Motion are considered together, it suggests an inertial like relationship between matter and space.
The GP-B experiment, not the only test, just the most recent and accurate test, of the geodetic and frame dragging (or the curvatures of space from gravitational effects and the Lense-Thirring effect or linear velocity of an object in space), demonstrated that the frame dragging effect does occur. The motion of the earth in this case in space does drag space along with it, in a weakly defined manner. This is published and pier reviewed and easily available from a Google search on Gravity Probe B.
The point that I was making is that since we can say with some certainty that the motion of matter in space does twist and drag space with it, even if only weakly, requires that space exert an equal and opposite force on the motion of that mass or matter in space, i.e. Newton's 3rd Law of Motion. This suggests an inertial like relationship between mass/matter and space. It is not in conflict with GR, as GR requires that space be thought of as dynamic, in its relationship with mass/matter and even the surrounding space. and since light moves through space any inertial character associated with space must be considered when discussing the propagation of light through space. This does not mean that light and space have an inertial relationship. It only suggests that we must consider the apparent inertial character of space as we examine the propagation of light over great distances. Still it must be kept in mind that the curvatures of space as described within GR are a manifestation of this inertial like relationship.
Very often space is thought of as empty space and that is then interpreted to mean that it is nothing "empty". This is not consistent with GR, experience or what we observe of the universe. Space must be thought of as having some intrinsic "substance" independent of the mass/matter within it. We just cannot attribute a particle structure to that "substance".., yet. Several approaches to quantum gravity have been trying. None have yet proven to be entirely successful.
This is all really straying quite a long way from the original thread, though as a foundation from which the original question(s) are examined it is still relevant.
I am not really sure any of what I have just presented speaks to your last statement about "my theory on gravitational effect", if it hasn't be more specific as to what you mean. From my perspective the only thing that may be "my" theory or interpretation, is the association of Newton's 3rd Law of Motion and the Lense-Thirring effect, as representing an interial like relationship between matter and space. Even that is nothing I could claims as revolutionary or unique.
How this all relates to the original question involving a finite or infinite universe with or without a boundary, involves how we treat or interpret the visible horizon of what we can observe of the universe. That in some respects is another philosophical discussion, which is influenced by the theoretical model one begins with, whether that is the BB or a cyclical Big Bounce and whether a singularity is a mathematically defined dimensionless point or simply a state in which the energy/mass/matter has no differentiation.
A singularity in practice could have volume and no differential structure. Kind of like a supper saturated solution, in which the big bang event is the disturbance that initiates differentiation. From that perspective the singularity before the big bang could have had any volume, including an infinite volume. In that case it would not be the universe that expands, it would only be the initial "crystallization" of matter and its expanding distribution in the universe that is being observed, as an expansion following the BB.
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The following is to correct an issue I have with my own following posts, [post="2839090"]Post 151[/Post] & [post="2839238"]Post 155[/Post]
Since both posts have been up for a while I chose to post what I hope is a clarification and correction here.
I really thought someone would have called me out on this earlier. Since no one has I will call myself out... In earlier post(s) while discussing/describing the relationship between the propagation of light and the Doppler effect I made an error of omission that leads to a false description of the Doppler shift and expanding universe model and argument.
Where I presented an argument that light could not be affected in its time of travel, only in its wavelength by an expansion of space, I presented an inaccurate description of that relationship and interaction.
Given that in the expanding universe model space expands uniformly everywhere, the small expansion experienced in a continous manner by a photon would slowly and over time shift its wavelength in a redshifted manner. In my previous post(s) on this issue I discounted the fact that space was expanding continously and the distance between a photon's instantaneous location and its eventual point of observation is also increasing constantly. My previous posts had presented the expansion of space as an instantaneous event rather than a continous process. Given a constantly expanding universe or space and a uniform velocity of light a photon's wavelength would both be increasing, proportionally to the instantaneous expansion local to the photon and its total time of travel would also be increasing proportionally to the global expansion of the universe and space.
Essentially a photon can both become redshifted by the local instantaneous expansion of space and its time of travel increasing by the global expansion of space. This would result in an expanding observable boundary or horizon. It would also suggest that at some time or point the redshift in the EM spectrum could be sufficient that events beyond the horizon could never be observed. Not just due to an overall rate of expansion greater than c, but because and EM from beyond a given distance would be redshifted to the extent that it becomes obscured by the CMB.
Since both posts have been up for a while I chose to post what I hope is a clarification and correction here.
I really thought someone would have called me out on this earlier. Since no one has I will call myself out... In earlier post(s) while discussing/describing the relationship between the propagation of light and the Doppler effect I made an error of omission that leads to a false description of the Doppler shift and expanding universe model and argument.
Where I presented an argument that light could not be affected in its time of travel, only in its wavelength by an expansion of space, I presented an inaccurate description of that relationship and interaction.
Given that in the expanding universe model space expands uniformly everywhere, the small expansion experienced in a continous manner by a photon would slowly and over time shift its wavelength in a redshifted manner. In my previous post(s) on this issue I discounted the fact that space was expanding continously and the distance between a photon's instantaneous location and its eventual point of observation is also increasing constantly. My previous posts had presented the expansion of space as an instantaneous event rather than a continous process. Given a constantly expanding universe or space and a uniform velocity of light a photon's wavelength would both be increasing, proportionally to the instantaneous expansion local to the photon and its total time of travel would also be increasing proportionally to the global expansion of the universe and space.
Essentially a photon can both become redshifted by the local instantaneous expansion of space and its time of travel increasing by the global expansion of space. This would result in an expanding observable boundary or horizon. It would also suggest that at some time or point the redshift in the EM spectrum could be sufficient that events beyond the horizon could never be observed. Not just due to an overall rate of expansion greater than c, but because and EM from beyond a given distance would be redshifted to the extent that it becomes obscured by the CMB.
Big Chiller
Registered Senior Member
I would like to know does the expansion of the universe alone cause the overall rate of expansion to be greater than c beyond the particle horizon or does the proposed acceleration of the universe do that.
I am not sure that the two can be thought of as separate. The accellerating expansion model essentially replaces the previous constant expansion model. In either model the cumulative expansion of the universe and or space could result in a rate of expansion relative to distant locations that exceeds the speed of light. This should barring any unknown effects, that the expansion might have on the propagation of light, result in a cosmic horizon beyond which any EM emission would be unobservable.
Just so this point is clear, I am not convinced that the big bang model or an constant or accelerating expansion of the universe is accurate. They both fit much of what we observe of the distant universe. But while we still have much to understand of our own solar system, it is difficult to assume that what we believe about the universe on a global scale can represent the final word or truth.
These models represent our best guesses in a way. They do satisfy and explain most of what we currently observe of the universe. However, there are other models being explored and still questions unanswered by an expanding universe.
Can you list at least some of these unanwered questions?
Horizon problem?
Flatness/oldness problem
Magnetic monopoles
Baryon asymmetry
Globular cluster age
Dark matter
Dark energy
Anything else?
Other than as a part of some popularized media.., a TV program or book, I don't believe anyone could give honest answers to all of those questions. Or for that matter some of those questions.
I will give you off the cuff opinions for a few.
I don't believe there is a horizon problem. I think that whatever the functional reason turns out to be there will always be some observable horizon to the universe.
I am unsure what you mean by, "Flatness/oldness problem". So there is nothing I could say about that.
Though a magnetic monopole would be a very sexy and useful thing, I personally don't think they are possible let alone exist. Magnetism itself still holds many secrets. We know a great deal of how and what things interact in a magnetic field. We know a great deal of how to create and to some extent control electromagnetism. But as with both inertia and gravity, the how and why of it at its most fundamental level is still something of mystery.
On the subject of dark matter and dark energy, I have been leaning in the last several years, toward the idea that both are functionally aspects the interaction of space and mass/matter and are more related to inertia and gravity than some new state of matter and energy. These I believe foretell the beginning of some significant change in our fundamental understanding of the relationship between GR and QM. I don't believe we will have a real answer until we also have a rigorously functional model of quantum gravity.
Baryon asymmetry is an issue for QM and though I try to follow some of what goes on there, I tend more toward GR, inertia and gravity.
Globular cluster age? I am unsure of your question here. But I suspect I would have no answer.
Anything else is a very big subject and on most of it I would either have no opinion or be unqualified to even make a guess.
Anyone with any real and diffinitive answers to questions like the ones you present, is either delusional or waiting for their nobel prize. I don't expect a knock on the door informining me that I have been nominated any time soon, and I really, really hope, that even though I spend a fair amount of time reading and thinking about these things, I am not delusional... Just opinionated.
The horizon problem is that of explaining why the universe looks smooth in all directions, if it expanded rapidly in the past.
Baryon asymmetry is the problem of explaining why the universe contains ordinary matter if an equal amount of antimatter was created. Where did it go?
Baryon asymmetry is the problem of explaining why the universe contains ordinary matter if an equal amount of antimatter was created. Where did it go?
Ah! O.K. As long as we are talking only opinions and not definitive answers....
As to the horizon problem or issue I don't really see as a problem.
If the universe began with the BB and a singularity, as long as we are sufficiently distant from the expanding boundary of the universe we should not observe any significant difference in the distribution of matter.
If as I suggested earlier that initial singularity were describe more as an undifferentiated volume of space, of any dimensions, similar in principal to a super saturated solution and the BB event was an initial disturbance resulting in differentiation, again as long as our cosmic horizon is completely contained within a differentiated volume of space or the universe, the universe should appear essentially smooth in all directions.
In either case only if our cosmic horizon included or came at least close to some boundary of expansion should we see anything other than a smooth distribution of matter and energy.
For a moment, think about space as "the universe" from a perspective consistent with GR. In some respects space itself appears to us as a nearly perfect liquid that interacts only weakly with matter. Though this could be read as leading to an ether model, that is not my intent here. However, from the perspective of GR space is dynamic and interacts with matter, so the analogy fits.
Continuing... I said nearly perfect liquid because we know that the speed of light is finite and a perfect liquid could be modeled such that kinetic motion is conducted instantly throughout. A near perfect liquid could then be modeled with a "speed limit", i.e. c.
Consider space as defined above now as devoid of any matter. As being undifferentiated. As a super saturated solution and being a perfect fluid. Any disturbance would be carried throughout instantly and could also alter the character of that initial perfect fluid, such that the resulting space would be more like a nearly perfect fluid filled with matter. This could in essence be a modified steady state model, that includes a BB like initial event. And it would also account for a smooth cosmic horizon in all directions. (A downside would be that it would also likely require a tired light model to explain the cosmological redshift and I am aware of no current tired light model that is rigorously consistent with both GR and QM.)
(This seems to be digressing into the Alternative Theories department more than math and science, but I will let others make a final decisions on that. We're just speculating here anyway.)
The Baryon asymmetry "problem" is both an issue for QM, an area I am not fully qualified for and philosophically one of our own making. It assumes that things began in a certain way. The fact that we observe what we define as antimatter both experimentally and to some extent in nature does not mean that antimatter is not an outlier phenomena, an anomaly, occurring only randomly.
But we aren't any distance from the "expanding boundary". The entire universe, including the part we're in, is expanding as it has been since the BB.OnlyMe said:
I don't follow that. Where or what is our cosmic horizon? What's a "differentiated volume" of space?
As to baryon asymmetry and antimatter: antimatter isn't an "outlier", the probability of antimatter and matter being created is equal today (as in particle physics experiments), and was equal in the beginning. The assumption, given recent data on hep experiments (as in, over the last 50-60 years), is that equal amounts existed at the beginning. So where's all the antimatter?
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