Where is the center of the universe?

Ich

Which kind of journal, if I may ask? And which kind of practice?
Yeah, great. Maybe sometimes you'll find the scale of these false color pictures. Try this one for a start..

Greylorn

Awesome link! Thank you! There is obviously more I can learn there before coming back on this issue. So, I will be getting back to studying.

Back in '75 when we were developing the imaging technology, we called it pseudo-color. "False color" is upfront and honest.

It never occurred to me to check the scale, which was stupid. (Of me, not the scale.) A difference of 0.018% seems downright negligible.

One curiosity, which I did not find answered on the page--- Is the low effect of galactic emission the result of a limited instrumentation bandwidth?

I appreciate your assistance and sense of humor, equally welcome.

Greylorn

Actually, I had thought that BB theory was derived from observational evidence, more a half vast body, but good evidence nonetheless.

I find the theoretical basis for the BB an issue. I do not believe in physical singularities or omnipotent gods. What caused the "singularity" to become a universe? Did it suddenly "decide" to become unstable?

Physics works as an effective combination of observation and theory. In the instance of the origin of the universe, I find good reasons to seek a theory which does not include a mystery hypothesis. Religion does that quite well already.

Ich

Yes, they're measuring in the microwave region only. You get a relatively undisturbed signal there.
Thanks, my humor is normally lost in translation, so I'm happy I could get through with it for once.
You know, BB theory works backwards. We see the evidence now, obviously, and trace back the history. And there was definitely something hot and dense. This knowledge is independent of musings about the origin.
You could also start from the beginning with the exact moment we know nothing about. But that's not science, that's philosophy or religion.

Greylorn

Me too! I suspect that your style of humor will generally be lost on those who take themselves seriously.

I find the method by which we've derived BB theory fully plausible. But, where it gets us does not feel right. I don't mean feeling in the emotional sense, but in the logical sense.
It seems to me that if we got there from here, we should be able to get here from there. That does not appear to be the case. This makes BB theory logically asymmetrical.

Then there is the persistent observation that we live in a cause-effect universe; where then is the Big Bang's cause?

50 years ago I gave up my belief in God for several reasons, one in particular being the absurd motivations attributed to this entity for the creation of mankind. BB theory seems to me to suffer from the equivalent failing--- lack of plausible cause.

Wherever we start can be fairly regarded as an hypothesis. Whether an hypothesis becomes the core of effective physical understanding, or the basic dogma of another religion, depends upon what we do with it.

If we can derive it mathematically from a bit of observational evidence, and test it empirically, then it's usually science. If it predicts something we'd otherwise not have known, then it is almost certainly science.

But if we insist that an hypothesis came inscribed on golden tablets, since removed to heaven, and cannot possibly test it, then it's religion.

If we wake up some morning suddenly knowing the secrets pf the universe, and wrap a bunch of coherent polysyllabic words around our notions but never bother to test any assumptions or trouble ourselves with predictions, we've got another philosophy.

IMO BB theory is in the neverland of what I'd call, physical theology. While derived by scientists, it lacks some properties which we normally associate with sound science. Moreover, the Big Bang's mysterious precursor shares more characteristics with the God of Christianity than with any known physical phenomenon. (Mysterious or non-existent origin, containing/creating all matter and energy, yet doing so without credible cause or purpose.)

Something's not right with BB theory.

Chronos

The singularity part is still conjecture. A number of prominent physicists currently suggest alternatives. Given that [according to most physicists] time [in this universe] originated with the BB, your causal complaint is irrelevant.Feel free to submit your alternative explanation that fits the body of evidence.

Fredrik

The original big bang theory is just the claim that the large-scale behavior of the universe is described by a member of a particular class of solutions to Einstein's equation. The theory that's built up around that equation (general relativity) describes an enormous range of phenomena including but not limited to: objects falling to the ground, the orbits of planets, the decay rates of fast-moving elementary particles, the fact that two clocks on different floors of the same building are ticking at different rates, redshift of distant galaxies (given that matter is distributed homogeneously and isotropically across the universe), the rate by which the frequency of a pulsar is changing (due to emission of gravitational waves). It makes predictions about all those things, predictions that are almost absurdly accurate. And you think the theoretical basis isn't sound!? That's very naive. This is the best theory in all of science, except possibly for quantum mechanics.

It's not a hypothesis. It's what the theory (general relativity) says must be the case if matter is distributed homogeneously and isotropically. (And according to the singularity theorems, if matter is distributed in any way that resembles what we see through a telescope). The comment about religion is just silly. You should probably refrain from making condescending remarks until you have some idea what the various big bang theories are saying.

That's clearly an emotional argument, not a logical one.

Even if all events have a cause, that principle doesn't apply to the big bang (in the original big bang theory) since the big bang isn't an event. There's no first event in the big bang theory.

That's absolutely false. No one who understands the big bang theories or knows what science is would make a claim like that.

Nickelodeon

If it isn't an event could you tell us what it is?

Greylorn

You may well be correct, but would you kindly explain why the non-existence of time eliminates the need for a cause--- specifically some force which rendered the micropea or singularity unstable?

Good plan. I came up with a few strange ideas a few days ago while being kicked around by Darwinists on a statistical thread, and they seem promising. (The ideas, not the Darwinists.) It will take a few months to work them out and put them on paper, and getting them published if they do work out seems an uphill struggle, but I will definitely follow your suggestion. Thank you!

blank.black

but the History Channel said there is a center point from where the Big Bang occurred and they had various scientists on there as well...is the History Channel wrong? are the scientists on there wrong? must i not watch History Channel? :(

Greylorn

I'm here to learn, and appreciate your sharing your understanding with me. I'll do my best to honor that with honest questions, which by my standard, are those which I think are important, and to which I do not have the answers. It has been a long time since I learned what I could about general relativity, and my math skills were not up to the job of understanding either its full derivation or its implications. I am aware of most of the effects you mention, and like you, I've marveled at their powerful predictive value. (That's real science!) But isn't time dilation, the most notably accurate of Einsteinian predictions, described by special rather than general relativity?

I'd not known about the pulsar frequency changes. Nor was I aware that gravitational waves have been experimentally detected. I imagine that this would not be essential to pulsar theory, but have noted that all too often, things which cannot be detected turn out not to exist.

Perhaps more relevant, I thought that general relativity can be interpreted as leading to the possibility of a Big Bang, not that it necessarily does so. Moreover, it cannot solve the initial condition problems. Envisioning a collapse of the universe if we run time backwards, it seems clear that time is greatly affected by the concentration of mass-energy in a tiny space. I'd expect the general relativity equations to collapse well before the universe became (running time backwards) the size of a golf ball, and to become absurd afterward.

Also, the concentration of all mass-energy in a tiny space will produce the great grandmother of all black holes, a black hole without an event horizon, and the absence of time would preclude quantum effects at the event horizon from evaporating the hole.

Do you know if these issues have been dealt with theoretically, and where I might locate the papers?

Clearly, the cosmological view of homogeneity differs from mine. I look into the universe and see subdivisions of lumps. If I poured out a bottle of homogenized milk with as many lumps as our solar system, or galaxy, I'd toss it as being spoiled.

Perhaps I should clarify it. If we can determine theoretically that there must have been a Big Bang (getting there from here), then we should also be able to determine, theoretically, why the Big Bang occurred. (Getting here from there.) I honestly do not understand what is emotional, or non-logical about that proposal. Clarify, please.

The "no event" notion smacks of religious beliefs in an omnipotent God who always existed without origin or cause, always knowing everything.

Nickelodion has replied to this more cogently, and I hope that you will answer him.

There, you are nearly correct. I will put my understanding of what science is, at both the ideal and practical levels, up against yours or anyone's. But I've been out of practice for a few decades, so lay no claim to actually being any kind of scientist, despite having done a fair amount of it.

You are correct in that I do not understand Big Bang theory. This could be because I am stupid, or could also be because Big Bang theory is not correct. I'm asking questions in hopes of correcting one or both of these issues.

Greylorn

IMO the History Channel does a lot of what I'd call, "speculative science." They are more imaginative than NitGeo, and I appreciate their willingness to explore ideas openly.

I also think that there are many fields of inquiry which mankind has pursued since our beginning, which are now dominated by scientists instead of theologians and philosophers. This is a potentially good thing, but I am noticing that many science followers take the same dogmatic attitude to the currently approved theories that religionists apply to their own beliefs. This is not a good thing, because dogmatism always stifles creative thought.

So, if you truly believe that science has correctly answered all important questions about the beginning of the universe and the origin of life, Thou Shalt Not Watch the History Channel. Else, perhaps Thou Must Watch It.

blank.black

but science has not answered all important questions about universe and life...just theories and possible explanations for mostly everything...that keep changing everyday due to new discoveries...hence making us buy new textbooks every semester

Quantum-lept

I did not take the time to read all posts, so someone may have pointed this out: If there is an edge to the universe, then there is a center. If there is no edge to the universe, then it is infinite, and there is no center.

But, would not expansion imply that there is an area outside of the universe to expand into? Or, if it is infinite, expansion is within and along the line of infinity?

I need to nap now, i overtaxed myself.

Having a center does not mean that it is a fixed point, as expansion may be uneven.

Fredrik

It can be finite without having an edge. Think of the surface of a sphere for example.

No. Think e.g. of an infinite line with distance markings on it, and imagine the distance between the markings growing with time. The scale is changing, but the total size isn't.

It's a mathematical property of a class of solutions of Einstein's equation. It can be characterized in many different ways. The most interesting detail is that the distance between two objects that stay at fixed coordinates in space goes to zero as the time coordinate goes to zero.

Each solution of Einstein's equation defines a spacetime. We're talking about a class of solutions, so we're also talking about a class of spacetimes. An event is a point in spacetime. A coordinate system is a function that assigns four coordinates (t,x,y,z) to each event. There's a specific coordinate system that's very convenient to use when we're dealing with these spacetimes. When I mention coordinates, that's the coordinate system I have in mind. If I e.g. mention "the time since the big bang", what I'm talking about is the t coordinate assigned by that coordinate system. (Everyone who understands this does the same thing. That phrase is defined to mean precisely that).

It's very important to understand that there is no event in any of these spacetimes that's assigned t=0 (or t<0) by this coordinate system.

There are lots of garbage claims in documentaries about these things, but I doubt that they had astrophysicists on the show who said that. It's definitely wrong.

Special relativity is one specific solution of Einstein's equation. There's time dilation in all of them.

They haven't. GR predicts that the frequency will change because energy is lost in the form of gravitational waves, and that prediction has been verified to an absolutely ridiculous degree of accuracy, by measuring the frequency.

All homogeneous and isotropic solutions have an initial singularity. That was known in the 1920's. The singularity theorems of Penrose and Hawking showed that a much larger class of solutions have initial singularities.

You're right that GR isn't expected to be accurate for very small values of t. But that's not a reason to think that your intuition about what things are like under those conditions are any better than GR. The theory that describes time in an intuitive way is Newtonian mechanics in Galilean spacetime. That fact that its predictions about results of experiments are much worse than the predictions of GR proves that our intuition is wrong about the properties of time.

If you mean the issues at times when GR doesn't hold, then no. Those require a quantum theory of gravity. If you're saying that GR says that the early universe would have turned into a black hole, that's just wrong. The solutions that say that a large concentration of mass in a small region will form a black hole, are only telling you what would happen if the rest of the universe is empty. In the "big bang solutions", the density is the same everywhere. It's a very different scenario.

It's approximately homogeneous and isotropic on large scales, but not on small scales. (Here "small" can mean millions of light-years). That's why the universe is expanding on large scales (distances to far away galaxies are increasing), but not on small scales (e.g. in the solar system).

Do I really need to clarify why "it seems to me" isn't a logical argument?

GR describes the relationship between how matter is distributed in spacetime and how it must move. If you plug in the (approximate) current distribution of matter, the resulting description of its motion includes a big bang (which is a property of spacetime, but not an event in it). The singularity theorems prove that it's not an artifact of the approximation.

This theory is also the best theory of time that we have. Experiments have proved that our intuition about time is wrong (certainly much more wrong than how this theory describes time). So it makes absolutely no sense to argue that there must have been a time before the events that these solutions mention.

To ask "why" there was a big bang (of the sort described by this theory), is to ask why Einstein's equation is an accurate description of the relationship between the distribution and motion of matter. That's a perfectly valid question, but you have to understand that it can only be answered by another theory.

That's the kind of comment I would expect from a creationist who isn't at all interested in learning what this theory says or what a theory is. (Edit: I changed this comment a bit because it sounded too aggressive).

Those are not the only two options. And to prove a theory wrong, you have to perform experiments. Just asking questions isn't going to do it.

Nickelodeon

Thanks for your extensive replies. I have difficulty trying to picture the Big Bang as a property of a class of solutions of Einstein's equations. Sorry but my maths is not up to much - by 'class of solutions of' do you mean 'subset of formulas derived from'? If you can't assign the value t=0 to the formulas, presumably due to fear of infinities, but you can assign t=0 + a miniscule amount, then it still feels like an event to me.

Einstein is reported to have said 'Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone'. I guess this example is the exception :-(.

Fredrik

I mean a subset of the set of all solutions to Einstein's equation. Each solution describes a spacetime, so I'm talking about a subset of the set of all possible spacetimes. Specifically, the set of all 4-dimensional spacetimes that can be "sliced" into 3-dimensional "spacelike hypersurfaces" (sorry about using another technical term) that are are all homogeneous and isotropic (in a technical sense). We can think of these hypersurfaces as "space, at different times". If we label them with a parameter t>0, it's a fact that in any of these spacetimes, the distance between any two objects that are "floating freely in space" (like two galaxies) goes to zero as t goes to zero.

The value of this parameter t is assigned in a way that ensures that the word "time" is appropriate.

I suppose it does, but we're talking about the theory that tells us what time is, so we can't assume that time has different properties than what the theory is saying. If the theory doesn't even mention a t=0, how can we?

I can think of lots of examples that are much worse than this.