[Goober5000]

Article or single page version

This is fascinating stuff.  In 100 billion years, it might be scientifically impossible to correctly determine the origin of the universe.

Unless a) somebody from the present left documentary evidence, b) it survived long enough to be read by future astronomers, and c) those future astronomers believed it.  That opens up a rather intriguing can of worms if one thinks about it a certain way.

[Mars]

In 100 billion years, the sun will be toast, and no one will be around to care.

Just thought I'd point that out.

[Mr. Vega]

You never know.

[blackhole]

While this applies to other civilizations, if you look at human's current exponential growth, our technology will be so stupidly advanced we won't give a **** about the origins of the universe - we'll just go make a few.

[Bobboau]

here is a fun thought, what does this say about our current understanding of the universe?

[perihelion]

That was my take on it as well.  How much information has already receded beyond our horizon?  If we can see a future where it will be impossible to tell how the universe got there, how do we know we aren't already there?

[Mefustae]

That was my take on it as well.  How much information has already receded beyond our horizon?  If we can see a future where it will be impossible to tell how the universe got there, how do we know we aren't already there?

We don't, we're just calling it like we sees it. That's what science is.

[Bobboau]

well wouldn't it be prudent to consider the possibility and try to think about ways of determining if it is the case?

here is a thought I had, not one I would expect anyone to take seriously, but I thought it was interesting. what if the nature of the universe is as some have suggested cyclic, but not in the boom and crunch cycle, but in more of an infinite recursion cycle. what happens when the event horizon gets smaller than an electron? a quark? the most basic subatomic particle that can exist that we haven't a name for yet? what if it's exsistance decomposes into a smaller scale sub particulate with time moving at a relatively slower pace, the sub elements,that in the universe just moments ago could not exist now flutter about interact and recombine in the small sphere of influence they still have, the sum total of the energy of this system would be the same as the particle which spawned it, but it fills the whole microcosm, which is still expanding, slowed locally perhaps by gravity, but still ongoing. you see where I'm going yes? the a universe spawned from an electron what seems to us to be a minuscule amount of energy could simply be scaled down, nothing in that universe would know it's energy was once a tightly packed point in a vast other universe, nothing could know.

and there is absolutely no way to test it, that is infuriating.

[WMCoolmon]

That's probably outside the scope of the article. I just read the first page and it's already using terms and concepts I'm unfamiliar with after a year-and-a-half's worth of physics classes. Granted you might talk about dark matter and stuff more in an astronomy class, but I doubt they'd go into the nitty-gritty equations and stuff.

My guess would be it'd be enormously difficult - running a simulation of galaxies to discover which galaxies are in the wrong position for the gravitational influences of other known galaxies, and then coming up with how off they are and if that could be caused by galaxies that we aren't aware of and can't be found using conventional means. Like Obi-wan Kenobi in Attack of the Clones (you know you're dumbing down science when you use Star Wars to illustrate your experimental process. But it works so well!)

But I think blackhole's comment raises an interesting point. By the time we as a race are 100 billion years old, and have lived to tell about it, the most efficient thing would probably be to just create our own universe, play God, and watch what happens. Why bother with trying to simulate the effects? By this point, we're already talking about quantum computers. By that point, if the rate of increase is the same, I have no clue what kind of computers we'd be playing with but they'd probably run on principles totally incomprehensible to anybody today, and require a lot finer manipulation of the universe than was ever possible before. The same principles could be applied to make a state of matter, basically a giant processor, designed to activate in a predetermined way and create a scale universe to our own. With a little time dilation, you could run tests in a matter of hours.

[General Battuta]

Yeah, the whole problem is, if we're behind such a horizon already, I really don't see any way to figure it out.

Shucks!

[Ashrak]

While this applies to other civilizations, if you look at human's current exponential growth, our technology will be so stupidly advanced we won't give a **** about the origins of the universe - we'll just go make a few.

thats like the best quoute EVER.

[Flipside]

An interesting assumption, assuming the universe behaves for the 100 Billion years exactly as it does right now, which isn't a certainty, in fact, it's becoming more and more likely that many 'constants' in the universe are more like 'temporaries', they've been different in the past, and may still change again in the future.

It also means that, if future humanity wants to develop any form of travel that is worthwhile, we need to forget about speed, speed shouldn't even come into the equation, because eventually there will be no speed fast enough, at least, if we want to travel outside the local cluster.

[Ghostavo]

My guess would be it'd be enormously difficult - running a simulation of galaxies to discover which galaxies are in the wrong position for the gravitational influences of other known galaxies, and then coming up with how off they are and if that could be caused by galaxies that we aren't aware of and can't be found using conventional means.

Not to mention borderline impossible. We are far far away from solving the three-body problem despite it being worked for almost three centuries that solving the n-body problem in our life-times could be considered nothing short of a miracle. And if we're hypothetically speaking about a civilization that advanced, we're not even sure the three body problem can be solved for a pratical solution, much less the n-body problem so the point at which their knowledge is might be moot.

[BengalTiger]

Another thing: And how do we know we aren't in a "created universe", made by someone 100 billion years from now, who wants to simulate how it looked like long ago to figure out it's origins?
Whoever read "The Science of Discworld" by Terry Pratchett will know more/less what I'm talking about.

[General Battuta]

Another thing: And how do we know we aren't in a "created universe", made by someone 100 billion years from now, who wants to simulate how it looked like long ago to figure out it's origins?
Whoever read "The Science of Discworld" by Terry Pratchett will know more/less what I'm talking about.

Yes.

And if the creation of such universes is possible, the probability that we are living in such a universe is just about one.

[CP5670]

Very interesting article.

As blackhole said though, if humans still exist that far into the future, they probably won't have anything in common with present day ones and wouldn't necessarily care about this anymore.

Not to mention borderline impossible. We are far far away from solving the three-body problem despite it being worked for almost three centuries that solving the n-body problem in our life-times could be considered nothing short of a miracle. And if we're hypothetically speaking about a civilization that advanced, we're not even sure the three body problem can be solved for a pratical solution, much less the n-body problem so the point at which their knowledge is might be moot.

It depends on what you mean by solving it. The 3 body problem is actually pretty well understood by now, and numerical solutions of the general case can be done as well.

Simulating the movements of galaxies in terms of their stars would of course be hopelessly complicated, but that might not be needed to get a reasonably accurate estimate.

[Flipside]

Simulating the movements of galaxies in terms of their stars would of course be hopelessly complicated, but that might not be needed to get a reasonably accurate estimate.

Kind of like Fluid Dynamics or Boyles' law, you don't have to understand the motion of every particle to understand the motion of the whole?

[perihelion]

That's a pretty good approximation, yes.  It is also similar to statistical mechanics.  In this discipline, you are essentially reducing thermodynamics to basic quantum mechanical principles applied in aggregate.  You may not know specific information about molecule XYZ, but you can make a pretty good prediction about what states exist in a cloud of gas and how many molecules fall into each state.  You don't even have to use a computer to make those kinds of calculations, it just makes it a lot easier.  In pretty much any physics problem, if you are standing far enough away to disregard some of the internal variation of a system, semi-analytical methods will work just fine to give you the "state" of the system as a whole.  It is when you want to know specifics about internal components of the system (in this case, stars and galaxies) XYZ that you start having to fall back on iterative approximations.

[CP5670]

Simulating the movements of galaxies in terms of their stars would of course be hopelessly complicated, but that might not be needed to get a reasonably accurate estimate.

Kind of like Fluid Dynamics or Boyles' law, you don't have to understand the motion of every particle to understand the motion of the whole?

Yeah, exactly. Many types of physical problems can be examined at a micro level (a big system of ODEs with each one describing the behavior of one particle) or a macro scale (typically a PDE that describes some sort of density of the whole system), and the latter is often easier to work with in these cases.

[Janos]

Simulating the movements of galaxies in terms of their stars would of course be hopelessly complicated, but that might not be needed to get a reasonably accurate estimate.

Kind of like Fluid Dynamics or Boyles' law, you don't have to understand the motion of every particle to understand the motion of the whole?

Yeah, exactly. Many types of physical problems can be examined at a micro level (a big system of ODEs with each one describing the behavior of one particle) or a macro scale (typically a PDE that describes some sort of density of the whole system), and the latter is often easier to work with in these cases.

.. and to dumb it down even further, we can still observe mass, velocity and acceleration; we know that we weigh something, we know what happens when objects that have mass interact. But whyyyyy hoooow