Big bang only makes sense to a particular energy/time/space limit. All the energy that came to be all the universe already existed. What happened 'before that' doesn't even make sense. I was told that 'creation' type language is a misunderstanding of the big bang.
Is that not still the way it works?
We have wiggle room for planck epoch because that time was after singularity, meaning that we have information from that time (however little of it is left).
Closest we got to science here is by extending the time and space axis across the diagrams point of origin. This is where idea of singularity being in heart of higher level universe black hole (or past universe’s collapse) comes from. Its inpossible to verify black hole idea due to deletion of information, but collapse/crunch should be observable in distant future of the universe. Perhaps dark energy still has some tricks up its sleeve?
https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology#Emp...
The fact that Penrose’s work is possible and ongoing is proof enough that scientific discourse on the matter is open and possible.
Science never has final say on what’s impossible. Until (if ever) we have a grand unified theory that perfectly coheres all we find and ever find, you cannot claim to know of an impossibility.
For example, an easy proof you’re wrong would be simulation theories. In that case, the Big Bang is just a sub-simulation inside a bigger universe. Can you prove we aren’t in a simulation? If not, then you cannot make any claim about how it’s not scientific to talk about before the Big Bang. We just don’t know, so taking the positive is an error.
In context of scientific debate, no Simulation theory exists. Only hipothesis, and a very weak one, considered it’s not falsifiable. Hence its treatment as curiosity and thought experiment by scientific community.
Your hypothesis needs to meet some requirements in order to be scientifically viable to research. You cannot throw out scientific method out of window because it appears „close-minded” to you.
Until proof appears that singularity is not errasing information, scientific approach is to find a proof that there’s no singularity as threshold between old and new universe within a cycle. And argument for that is currently based on interpretation of some features pf cosmic background, which is scientifically debated.
The quantity of nodes in a branching tree of causal events can grow larger without time or space if there is no reccurance for any given state to be compared to another.
From the "gods eye view" the tree "grows" even if there's no internal information which can be used to recover any space/time prior to reccurance.
It's only an issue if you think about space and time as separate things. I find it makes (a little) more sense when you understand that time is a function of spacetime. Therefore if you're happy with space not existing prior to the big bang (which people do seem to be OK with) then automatically time didn't exist either, and hence 'before the big bang' ceases to be a problem.
Think of time as "it prevents everything happening at once". Before there was time, nothing prevented everything happening at once, without space nothing prevented everything happening in the same place, so everything happened at once and in the same place. That everything happening made so much noise that it created space and time in a very big bang.
I suppose the question comes to, what is time? I imagine "time" to be a degree of freedom through which something can change. I understand some see time to be related to entropy, and that it's an emergent property of this thermodynamic property but this seems too limiting. It would seem entropy is more-so an explanation for the arrow of time, but not time itself.
If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?
Not "something". Everything. Like "What is possible to happen? Everything is possible". If you can't divide that possibility by time period, everything possible will happen with probability of 1. How improbable is that universe will happen during 1 trillion years? Very improbable. But if you can't tell in how many years universe will happen, it just will exist.
> but what does that mean for this to "happen all at once"
If you don't have time to make difference between two things happening one after another, they will happen both at the same exact "time".
> If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?
The problem is, time depends on local state of space. More energy/matter in a chunk of space means time is slower relative to other chunks of space. So when you try to go into past with mass in chunk of space increasing into infinity, that time notion breaks.
The same is true of "space" for the same reason. A causal network without reccurence (a tree) has no way to compare objects since there are no horizontal relations and it cannot "look" at backwards relations.
A non-reccurent causal tree has multiple instances of "here" and "now." But without anything to compare a given here/now to the concepts are internally meaningless.
There is no timeline by which to order cause and effect.
I would argue that the second sentence implies the first isn't true. You can't imagine that there is no time if you're saying things can't happen without time. What I said doesn't mean things can't happen, it just means they happen in a way that doesn't require time to exist (which could be everything happening in the same irreducible instant, or in any order, etc.)
“it just did” has never been a satisfactory answer inside of churches or seminaries. That is why almost all the metaphysical discussion in these areas of human thought are around why we exist (in human terms).
“it just did” has been a satisfactory answer outside of churches or seminaries. This is why almost all discussion of why there is something rather than nothing in secular academia is ‘meh, impossible to know, don’t worry about it’
Intrinsically information about prior contingencies are unrecoverable "before" recurrence. But unrecoverable is not "non-existent."
How does this notion of time become decoupled from space?
One way I imagine it is that "time" as a concept encapsulates at least two properties:
1) The degree of freedom (i.e., dimension) through which things can change; and 2) The unidirectional flow of causal events
Relativity seems more concerned with defining time in terms of casual events (e.g., event horizons) than its dimensionality. If we define "fundamental time" as a dimension that allows for change can it then be decoupled from space?
ds^2 = dx^2 + dy^2 + dz^2 - dt^2
Thinking in terms of 3 dimensional euclidean space, this makes sense. If you fix your 3 dimensional coordinate system and pick 2 points in space, you can have:
ds^2 = dx^2 + dy^2 + dz^2
Simmilarly, in the 4 dimensional spacetime defined by the metric:
ds^2 = dx^2 + dy^2 + dz^2 - dt^2
The only complication here is that rotating your axis under the Lorentzian metric require the Lorentz transform; whereas rotating them under the Euclidean metric requires the Galilean transform.
The coupling described here involves no notion of causality. Nothing in the metric prevents a path from traveling in both directions along the time axis.
Further, if two events have are separated by a negative ds^2, then all observers will agree on the order in which they happened, though they will not agree on the length of time that passed between them, or the relative positions.
Note that I'm using your version of the equation for the definition of ds^2 > or <0, though in general I've seen it expressed the other way around, ds^2 = dt^2 - (dx^2+dy^2+dz^2).
We can distances with ds^2 < 0 timelike, and ds^2 > 0 spacelike. We say that events with a spacelike cannot influence each other; but there is nothing in relativity that requires that (unless you introduce causality as an additional assumption, which we generally do).
This gets more messy in general relativity when you allow for large masses (read. Black holes).
In the case of a non spining black hole, we spacetime is described by the Schwarzschild metric. Expressing this metric in spherical cordinates, you find that when you pass the event horizon the sign of dt^2 and dr^2 flip, where r is distance from the singularity. This means a "timelike" seperation means that events are closer to each other in the time dimension; and events with a "spacelike" seperation are farther from each other in time. That is to say, "time" behaves in the way we think of as "space", and "space" behaves the way we think of as "time".
Actually, time does not exist. It's simply the rate of change of matter.
The force from the big bang was imparted in an instant yet gravity is a constant force. IANAP but surely at some point the accumulative force of billions/trillions/... of years of gravity overcomes the force imparted by the big bang and the universe compresses into a singularity again?
I'd really appreciate someone explaining why this isn't obviously the case.
Space is expanding.
Objects far apart are traveling away from each faster than the speed of light. Or more that the space between them is expanding faster then the speed of light. So those objects will never have any sort of interaction.
Only ways around this if space itself start contracting. (No known way for this to happen).
Or somehow the universe is a big circle, and going far enough brings you back to the starting point. Negative curvature.
We don’t have any good theories on this. Some highly interesting ones that move the problem up a level.
For Example one theory is our entire universe is inside a black hole created from the remains of a four dimensional hyper star.
The math seems to work. Soo cool. But then where does the hyper star come from?
It’s “turtles all the way down”, is the thought to lot of the best theories.
Or everything is a simulation, again math kind of works. No direct evidence, but neat idea. But who’s hosting the sever that’s running the universe.
Something from nothing problem is a real trouble maker.
Its programmers all the way up!
But really, awhile ago I settled on the belief that its very possible we're in a natural simulation. Natural, as in, the same way that plants are simulations of L-Systems or in particular the same way my GPU once spat out cellular-automata-like behavior in a glitch.
If we are in a simulation, we've got no prior on what the world "above" us might be like. Oftentimes I see the theory shot down with "Our universe is too big and complex, theres no way any computer could be big enough to simulate it!" which is valid if assuming scale and physics anything like ours. But that's not a reasonable assumption here. It could be that the computational power of a cheap smartphone in the above world is similar to what a supercomputer the size of Jupiter or even Sun or any scale really for all we know. But that still assumes a programmer. If computing is done a lot in the above world at that sort of scale, our universe could be the result of a hardware glitch. That specific scenario may be quite unlikely, its just the extension of the GPU creating cellular automata by chance that I mentioned earlier. There's many other ways for algorithms of simulation to naturally emerge from reality just existing and things within it creating new sub-systems, which from within such a system, appear to be "something from nothing". So in a sense, it seems most likely that whatever the case is we are likely not one the "first layer" of reality, we are "simulated" within sub-layers. So then the interesting question is not how did this particular something come from nothing, but how can anything come from nothing, in the very first place, ever, at all? Once something exists, while scientifically we'd want an answer for how to get from there to here, its just a matter of what exact process that is.
I was also under the impression that an expansion of space would just reduce the gradient of the gravity along that space and not inhibit its propagation.
If like a bubble space has some form of surface tension then would there be a point that it can no longer expand? Gravity could then become dominant and force the contraction. -edit-> I guess that wouldn't contract the space though just the matter?
I promise I'm not being pedantic or contrarian for the sake of it but to further my knowledge, thanks for your input!
According to out current best cosmological model, Lambda-CDM (which, admittedly, is mostly a phenomenological model for things we only half understand, but still describes our current observations better than any competing model), gravity used to be the dominant force in the universe when it was smaller so that the masses were closer together until quite recently. But now it looks like the expansion, the "Lambda" term in "Lambda-CDM", the cosmological constant of general relativity, has become the dominant force in the universe, and the universe is slated to expand ever faster.
It could start to contract if Lambda were closer to zero, but it currently doesn't look like it might move there. But then we don't know why Lambda it there at all and what causes it not to be zero in the first place, as everyone expected it to be until about two decades ago (Einstein himself thought of the introduction of the term into his theory as a blunder, as it would obviously be zero in any sane universe.)
Maybe at the border of the universe there's a crunchy layer of mass that at some point gravity force will win over expansion.
Space is infinite and increasing.
Matter is fixed and static.
So a bigger infinity divided by a smaller infinity.
Which means density is heading towards 0. This is heat death of universe.
Now since dividing infinity by infinity is nonsense, this a sign our understanding is incomplete
To say it in another way, the energy used to expand the universe today is not only the initial force imparted by the big bang but is added to as part of quantum processes in empty space. However as the universe expands, the amount of matter (dark + luminous) does not increase so the proportion of gravity/matter to dark energy (the force that accelerates the expansion) is getting lower and we get an acceleration.
These observations exclude the possibility of a "big crunch".
Disclaimer: I am a statistician not a cosmologist but this is how I have understood it.
An interesting thing happens.
When you tear a quark away from it's antiquark, you get two quarks. The energy is equal to that required to bring another quark into existence. At this point, the rate of expansion is so vast that every quark in the universe has been forever isolated from one another, and then each bursts into a sea of high-energy quark-gluon plasma. The massive energy of expansion is rapidly consumed generating these quarks, and then the expansion slows, never stopping, but continues at a much slower rate.
Wait... we've seen this before. A quark-gluon plasma, rapidly expanding from a single point, in a universe isolated from all others.
Only expansion is required to generate new universes, forever.
Personally, I’m stumbling on understanding physical fields. This looks like another field is being added, which is nice in some sense, but why do we have the number of fields that we do and what conditions are needed to create/sustain physical fields?