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The Big Bang theory has formed the basis of our understanding of the universe's origins since it was first proposed in 1927 by Georges Lemaitre. And for good reason: the theory is supported by scientists' latest observations and experiments, and is based on Einstein's widely accepted theory of general relativity. But scientists are always on the lookout for any evidence that might suggest an alternative to the Big Bang. The latest in this area of research comes from astrophysicists Maximo Banados and Pedro Ferreira, who have resurrected a theory of gravity from the early 20th century and discovered that a modified version of the theory may hold some surprises.

In a recent study published in Physical Review Letters, Banados and Ferreira have reconsidered the theory of gravity proposed by Arthur Eddington, a contemporary of Einstein. Eddington is perhaps best known for his trip to the Island of Principe on the west coast of Africa in 1919, where during a solar eclipse he observed that the Sun's gravity does indeed bend starlight, providing one of the earliest confirmations of general relativity.
Although Eddington played a significant role in developing general relativity, during the following decades he became more interested in finding a theory to unify gravity and quantum mechanics - a task that is still being studied today. In 1924, Eddington proposed a new “gravitational action” as an alternative to the Einstein-Hilbert action, which could serve as an alternative starting point to general relativity. In astrophysics, a gravitational action is the mechanism that describes how gravity can emerge from space-time being curved by matter and energy. However, Eddington’s theory of gravity only worked for empty space and didn’t include any source of energy such as matter, making it an incomplete theory.
Since Eddington’s proposal, scientists have attempted various ways of including matter into the theory, although they have run into problems. In this study, Banados and Ferreira have tried a new way to extend the theory to include matter by using a gravitational action called the Born-Infeld action.
In their analysis, the scientists found that a key characteristic of Eddington’s revised theory of gravity is that it reproduces Einstein gravity precisely in the vacuum conditions (with no matter), but it produces new effects when matter is added. Due to this characteristic, the revised theory has implications especially for high-density regions, such as in the very early Universe or within a black hole. For instance, the theory predicts a maximum density of homogeneous and isotropic space-time, which could have implications for black hole formation.
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More intriguingly, the theory could lead to an entirely new view of the Universe that doesn't include a Big Bang. In Big Bang theory, the state of the Universe is a singularity in early times, meaning that the Universe was once infinitely small. However, Eddington’s revised theory requires a minimum length of space-time at early times, which means that the Universe could not have been a singularity. The theory predicts that, depending on the Universe’s initial density, it may have loitered for a long time at a relatively small size before growing large enough to be controlled by standard cosmological evolution. Another possibility, depending on the initial conditions, is that the Universe could have undergone a bounce, resulting from the collapse of a previous Universe. Any kind of singularity-free Universe would solve the singularity problem that has bothered scientists about general relativity, since a singularity cannot be mathematically defined.
“Taking as a starting point what is a very old idea, we have ended up with a theory that has this very interesting property of not having singularities,” Ferreira, a professor of astrophysics at the University of Oxford, told PhysOrg.com. “It was unexpected and definitely not what we were looking for.”
In the future, Banados and Ferreira hope to perform a more detailed analysis of the gravitational Born-Infeld action. While the current study only looks at the classical behavior of the theory, there could also be quantum behavior, such as with the bounce concept. In addition, the scientists plan to look at the possible effects of a cosmological constant, which they did not investigate here. However, they note that the theory is still in the early conceptual stages, and has a long way to go before they know how accurate it is.
“The alternatives to Einstein's theory are all hypothetical possibilities,” Ferreira said. “The goal is to try and find some key observational test that may distinguish between Einstein's theory and the one we have stumbled upon.”


[Source]: Revised theory of gravity doesn't predict a Big Bang
 

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This is really interesting! The fact that this "revised theory of gravity" doesn't need a singularity could make way for "brane theory." During an episode of Horizon, a new theory of how the universe might have formed was disscussed. It states that these two branes ( 2D sheets made out of strings) collided and that's how all matter and energy came into being. I should really read up on it more as this could be evidence! Thanks!:laughing:
 

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"No, the universe was not infinitesimal for an indeterminate amount of time before anything we can see happened, it was almost infinitesimal for an indeterminate amount of time before anything we can see happened."
 

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Quite frankly, I don't see this as anything but another hypothetical alternative. There are many attempts to explain gravity.

In inflationary cosmology, the singularity wasn't infinitesimally small, but rather reached a certain critical density. In loop quantum gravity, gravity emerges from loops of space itself. String theory posits a graviton as the transmitter particle for gravitational fields. Still more recently, I read Verlinde's proposal, wherein he describes gravity as an emergent, entropic force and derived Newton's universal law using first principles of thermodynamics.

The fact that this "revised theory of gravity" doesn't need a singularity could make way for "brane theory." During an episode of Horizon, a new theory of how the universe might have formed was disscussed. It states that these two branes ( 2D sheets made out of strings) collided and that's how all matter and energy came into being. I should really read up on it more as this could be evidence! Thanks
I believe it's a collision between two 3-branes (it theorizes that our universe is just a large 3-brane). You're thinking of Tolman's cyclic model for the braneworld scenario, and that's just another theory -- yet to be empirically verified.
 

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I don't study this kind of thing. Why is gravity so hard to explain?
 

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Big Bang isn't based on gravity. It's based on "if I look at where that galaxy is moving and where this other galaxy is moving and then extrapolate earlier positions they end up on top of each other, along with all of the galaxies."

Inertia's only connection to gravity is that both involve mass but gravity pulls mass together- how would that have ever been the origin of all this matter heading away from all that other matter?

You might wanna cut the google add out when you copy and paste articles from writers that don't seem to understand that Big Bang has nothing to do with explosive force though.
 

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Time and time again scientists discover amazing new perspectives when they were looking for something completely different.
 

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I sure love these.

They are always fixing their shit XD

They got this new one as of yesterday that is pretty badass I'll post a thread of.

I'd post it here--but it DOES predict a big bang so it'd be a bit off topic :O

(Even though it does it in a bit different sense)

EDIT: Here is a linky-- http://personalitycafe.com/science-...e-black-hole-another-universe.html#post569955
When someone bothers to explain how the gravity, stretched thin covering the vast reach of our universe, suddenly rebounds to such a magnitude that it can distort time and space to the point of creating an event horizon I'll give that a second look.

Until then stuff like how homogeneous the CMBR is is reason enough for me to think we don't have any kind of edge in our universe, such as what you'd have to have if we werea black hole.
 

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I have herd that the light cone of the universe prevents us from knowing how big it is. As for the big bang I'm not entirely convinced by its line of reasoning. Where did this singularity come from exactly? Why did it have the finite amount of mass it did? What if another one happens near my apartment and ruins my plans for this evening? :laughing:
 

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A: If not saying anything about "where did it come from" is suitable grounds for rejecting things you should be questioning gravity and that sort of thing too- last I checked scientific theories pick a starting point after their thing is already there and then tell you how it acts. If you want to know what starts a big bang you'll have to look for some theory talking about stuff from before it.

B: Actually all signs point to infinite matter. When you zoom way out and look at the observable universe the whole things looks the same everywhere*. With a half a universe of matter having all that gravity tug you one way and another half tugging in the opposite direction stuff would be pretty much how we see it but what do you think would happen near an edge? You'd have a whole universe of gravity pulling toward the middle and nothing pulling the other way. Then stuff a little ways away from the edge would still have to be different and stuff closer in would still at least be uneven- yet we don't see anything like that.
*further away it takes light longer to reach us so we don't see exactly the same thing very far away but it all looks like what the closer stuff should have looked like back then.

Add on how all of our measurements have been as close to showing flat geometry for the universe (meaning it doesn't loop around) as we can even measure and there's a pretty simple conclusion- infinite matter spread out roughly evenly over infinite space. So we've got this pretty constant density of matter but if it's spread out evenly any amount would work like that, yet there's more. Because the universe is expanding, because the space itself is getting bigger, we're spreading the matter thinner as time goes on. There are probably some technical issues with this but it seems like we could start with any high density and eventually reach a lower density just like what we've got now.
 

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Big Bang has more things going for it. For instance, it neatly resolves Olber's Paradox, the current types of stars there are,3 K-radiation, and probably many more things.
 

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I think and have thought for a while that The Big Bang theory is kind of stupid. Primarily because it assumes that there was a point where the universe didn't exist and that there is a different point now where it does. It would be simpler for one state to exist continuously. Occam's Razor should apply, no?
 

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I think and have thought for a while that The Big Bang theory is kind of stupid. Primarily because it assumes that there was a point where the universe didn't exist and that there is a different point now where it does. It would be simpler for one state to exist continuously. Occam's Razor should apply, no?
Well you sure dug up an old thread to say...

Ok so actually the big bang doesn't say that. I swear every ignorant grade school teacher says that big bang says that but it should be no surprise that most of them are not all that great at science. So here's the starting idea for the theory: "Hey, all the galaxies and things are moving and there's this really blatant pattern to it: They are moving away from every other thing, and moreso for things that are further from them." At first the thought is just "It's all moving away from us" but when you look a little closer you get that it's all moving away from everything. Gravity is strong enough to override this for some really close stuff but it wasn't moving away very fast anyway.

Ok so stuff's getting further away and stuff tends to keep going in the same direction if it doesn't have any friction or other forces messing that up. So there's no real way that endless ocean of space could have just bounced these things off of each other for the pattern like that- the simplest way to explain it is that everything has been traveling in those directions for as long as there was travelling to be done.

That is where people get that stupid notion in there head that there was nothing prior to the big bang. Instead what science actually does for that is crunch the numbers going back through time and things get closer and closer and closer until everything is packed into such a hot dense glob that physics doesn't even make sense anymore- so we stop. Maybe there's something before that but space and time as we know them don't mean anything past that.


Continuous existence is certainly not incompatible with the glob that makes numbers hurt but the most popular idea among scientists today is that string theory thing (hardly a theory at all but we've just GOT to be inconsistent with word meanings to make things harder on everyone.) You've probably heard about how it says that the smallest building blocks of existence are little wavy strings but for asking about the origins of things there is the more important issue of all those dimensions.

No, not portals into other words. Dimensions like on graph paper. Up/Down Left/Right In/Out- well with string theory there are 11 total (if you use Occam's Razor a bit,) and we're in a sort of bubble that's mostly just taking up space in four of them (time) while it's damn near flat in the other seven. The whole thing says the big bang began when two membranes collided (something about ripples causing the little dense spots that became galaxies I think,) and that this happens all the time.

There's not a lot of support for it but that's kind of the big thing about science: people are predicting what we will find. Eventually one of those massive supercollider machines we build or some other kind of apparatus will give us some actual evidence for or against superstring theory and then everyone will get all flustered and get to work on exactly what it means and the implications of it but for now that's about as far as we go.

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As for your use of Occam's Razor- it's simpler for there to not be anything at all. With Occam's Razor you're not just looking for the simplest thing but rather the simplest explanation of what you see. Because all those galaxies are moving like they are you'd have to add in all kinds of fictitious forces to somehow make the universe constantly exist in a way remotely like it is right now.

Props if you were able to muster the willpower to read all of that. If you've got any questions or objects I would be happy to elaborate. You wouldn't believe the stuff I left out to keep this under one page long (on my monitor.)
 

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Wow, I feel like a dumbass for not checking my facts. Haha, but thank you.

I've always been told that it's an explanation for the "creation" of the universe. Hmm. Is there any place in particular I can read about string theory and its dimensions?
 

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No problem, it's really common misinformation and generally we expect teachers and such to not be making shit up when they talk about science.

-The wikipedia pages for string theory and related topics have a few easily read paragraphs but a lot of the time they delve into a bunch of particle physics talk that I have a hard time making any sense of and they seem to leave a lot of questions unanswered. The discovery channel has had a lot of "Universe" themed programs with a fair amount of input from practicing physicists (sometimes big names even,) and that's all the easier to follow because they have big animations to put behind the talk of what's going on. They still do backwards shit like calling the big bang and explosion in almost every one (instead of expansion, it's a pretty fundamental difference,) but those kinds of programs are pretty much the best resource. Going beyond them- well, there doesn't seem to be very much material for people past layman introductions but before physics degree education. The field is still comparably young and malleable so it's going to be a few years before people make a lot of material in that range.
 

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None can define gravity..all conjecture that follows is known as the bollicks theorem
How you like em apples Einstein..or newton should you favour him.
 

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None can define gravity..all conjecture that follows is known as the bollicks theorem
How you like em apples Einstein..or newton should you favour him.
Gravity is the force, whatever that may be, that pulls all objects with mass toward each other. Very easy to measure as scale larger than the quantum universe too~
 
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