Something beyond visible universe detected?

[Moontanman]

Something beyond visible universe detected?

[sanctus]

Wow, that is really interesting!!

[RCP/CRT/RRT]

Hmm... Interesting indeed. How is it possible however? Since gravity & light are speculated to be the same speed...(?) I wonder about some of these "Breaking News" stories...

[RCP/CRT/RRT]

Going through some of my saved science bookmarks, I viewed this article again, and began to think.

 

Since gravity had separated from the theorized unified field before the last scattering, would that make it possible? The gravitational influence may have begun before then?

 

Kinna need someones expert analysis to determine if that's relevant....

[modest]

Hmm... Interesting indeed. How is it possible however? Since gravity & light are speculated to be the same speed...(?)

 

Great point.

 

Since gravity had separated from the theorized unified field before the last scattering, would that make it possible? The gravitational influence may have begun before then?

 

Certainly the thing affecting this cluster could be outside the visible universe, but inside the observable universe. This way it would not be visible being outside the surface of last scattering, but it would be inside our past light cone while the universe was less than 380,000 years old.

 

 

Sanctus, is it possible for something outside our past lightcone to affect a recession speed that we are seeing now? Since gravity propagates at c, wouldn't it make sense that if it can affect something gravitationally that we are currently observing then it would need to have been inside our past lightcone at some point, and thus 'visible'?

 

~modest

[coldcreation]

But a theory called inflation offers a solution, the physicists said. Inflation is a brief hyper-expansion that would have occurred right after the Big Bang. The result would be that we can see only a little of the cos*mos, because of how far and fast different parts of the universe burst away from each other early on.

 

I like (not) the way inflation offers solutions every time a discrepant observation comes to light.

 

Cool article though.

 

I don't see why something outside our light cone would not affect something in it, provided that something resides in the light cone of the cluster in question.

 

 

CC

[sanctus]

Ok a link to their paper is: this.

 

Modest, I think that they have once to have been in the past light cone, hence observable universe (not forcefully visible, as pointed out in the page you linked to). If you draw many future light cones for different points in the x years in the past and the big cone causally connected to us (which is of the form [math]\stackrel{\bullet}{\bigvee}[/math] where we are the dot) you can see that we can actually see effects of things never in causal contact with us (no contradiction, we see something which is far from us and hence has in its "causal horizon" stuff which is not causally connecte to us; but I guess modest you know all this better than me)...just as CC said.

 

But (there is one ;-))it they talk about an influence of another type of inflation and/or pre-inflation-remnant outside our present-day horizon.

 

Actually there is also a second but, I have to ponder it a bit more to be sure that it is not bs what I say.

[modest]

I'm getting myself confused. I always seem to confuse myself on this subject.

 

I don't see why something outside our light cone would not affect something in it, provided that something resides in the light cone of the cluster in question.

 

Yes. Clearly something outside our past lightcone can affect something inside it. But, if you add one more constraint: that we observe the effect today, then I'm less sure.

 

Modest, I think that they have once to have been in the past light cone, hence observable universe (not forcefully visible, as pointed out in the page you linked to).

 

Yes. That's what I was thinking

 

If you draw many future light cones for different points in the x years in the past and the big cone causally connected to us (which is of the form [math]\stackrel{\bullet}{\bigvee}[/math] where we are the dot) you can see that we can actually see effects of things never in causal contact with us (no contradiction, we see something which is far from us and hence has in its "causal horizon" stuff which is not causally connecte to us; but I guess modest you know all this better than me)...just as CC said.

 

:confused:

 

I'm not sure what you mean by causal horizon. It sounds like you're describing what I would call the particle horizon, the blue dotted line at r₀ = 46 here. It makes sense to me that anything inside that horizon would have once been in our current past lightcone and is therefore observable (either through gravitational effects or some other unblocked method that propagates at c). We, of course, wouldn't be able to see what that mass looks like today, but we would be causally connected to it as it existed in the early universe.

 

But, anything outside our current particle horizon, I'm unsure how we could currently observe its gravitational effects. I really don't understand inflation theory though. I guess it might make sense that inflation would quickly pull matter out of our horizon, yet the space left in its wake would (or could) indicate the density of that mass. As the paper says:

 

Such a motion is difficult to account for by gravitational instability within the framework of the standard concordance CDM cosmology but could be explained by the gravitational pull of pre-inflationary remnants located well outside the present-day horizon.

 

... and now I have a headache :hihi:

 

~modest

[modest]

Modest , I've seen the thread you link; interesting , if a little confusing for me ,though.

The way I see it the Kashlinsky work is a new problem for L-CDM model, and as that is being fought by many cosmologists like ned wright and others that try to dismiss it quickly.

 

The data, if verified, wouldn't really represent a direct problem for standard cosmology. It is more an addendum to it. Standard cosmology always starts with the simplifying condition that space is isotropic and homogeneous. If the universe is not really isotropic then standard cosmology would still be (just like we know it is) a first order approximation.

 

Think of the way that a comet's orbit doesn't exactly fit a Kepler orbit. Is that a problem for Kepler's laws? No.

 

~modest

[quantumtopology]

Think of the way that a comet's orbit doesn't exactly fit a Kepler orbit. Is that a problem for Kepler's laws? No.

 

Not for Kepler's laws . but surely for cosmologists if they want to calculate this orbits with great accuracy. If they had no problem with Kepler's laws they wouldn't talk about things like dark matter to explain the orbits of the stars in the outer arms of elliptic galaxies. :shrug:

[modest]

Not for Kepler's laws . but surely for cosmologists if they want to calculate this orbits with great accuracy.

 

I think you may have missed the point. A Kepler orbit does not take into account things like solar radiation pressure, general relativity, and the gasses escaping from a comet. It is therefore known to be a first order approximation to a real orbit. So, it's not unexpected that a comet does not exactly follow a Kepler orbit. Likewise, we know the visible universe is not exactly homogeneous and isotropic, yet Friedmann cosmology assumes that it is. Therefore, it is not a surprise that inhomogeneity and anisotropy are not reflected in a Friedmann universe. A Friedmann universe is a first order approximation to the real thing. This is not a problem, but rather a known limitation of the model. Any data that reveals anisotropy (which this data may do—very exciting!) would be an addendum to the ΛCDM model.

 

If they had no problem with Kepler's laws they wouldn't talk about things like dark matter to explain the orbits of the stars in the outer arms of elliptic galaxies. :shrug:

 

Newtonian gravity is a good first order approximation for a star's orbit around a galaxy when one properly uses the correct mass distribution of the galaxy, which includes dark matter.

 

~modest

[enorbet2]

When people point out "difficulties" with Classical physical Laws I think it is good to recall for example that the "Three Body Problem", typified by the interaction of Earth, Sun and Moon, was for centuries considered essentially unsolvable and remained so until computation devices were properly employed with newly discovered data.

 

Then once Quantum Mechanics began to grow the so-called "unsolvable problem" became possible to solve with pencil and paper by understanding the probability of the system flying apart.

 

This doesn't refute Kepler or Newton, nor is it an Ad Hoc, Deus ex Machina fix, it's just another way of viewing the same thing and are for the most part entirely consistent.

[Pyrotex]

Something beyond visible universe detected?

It's the return of Cthulu.

[Little Bang]

Newtonian gravity is a good first order approximation for a star's orbit around a galaxy when one properly uses the correct mass distribution of the galaxy, which includes dark matter.

 

~modest

 

The rotation curve is problem for science, so hey, let's just invent something. Isn't that kind of like sticking our head in the sand?

[modest]

The rotation curve is problem for science, so hey, let's just invent something.

 

To be consistent with the data one can use Newtonian mechanics with dark matter or try to modify the laws of gravity such as with MOND.

 

~modest

[quantumtopology]

To be consistent with the data one can use Newtonian mechanics with dark matter or try to modify the laws of gravity such as with MOND.

 

~modest

Have you heard of MOG, Moffat's theory of gravity? I have only read what it says in the wikipedia but it seems interesting;I think it's worth to take a look;

Most people I know that have heard of MOND, don't know about MOG;

Of course if somebody decides beforehand that Dark Matter is the only explanation, noone is gonna be able to show them that there are alternatives to a fudge factor that is just so easy to accomodate to anything.

 

Regards

[modest]

I haven't heard of it. I'll take a look.

 

~modest