Cosmology: A Thought Experiment

[coldcreation]

If one were to run the clocks backwards in an expanding universe, all the galaxies would find themselves in a 'free-fall' towards any observer, and all the matter in the universe would reach the same point at the same time. This is the type of linear field that permits a singularity at the outset.

 

A Thought Experiment:

 

To clearly visualize what the 'free-fall' entails (if time ran backwards) let's resort to a mind experiment. We're about to embark on a high-speed flight to oblivion. The fasten seatbelt warning is flickering for all you travelers out there. So sit up straight, buckle-up for safety, and enjoy the trek.

 

Two observers set out on a journey through the universe. Their mission: to see which model of the universe best fits with observation. Both will depart simultaneously from Cape Canaveral Air Force Station aboard modified Delta II 7920 expendable launch vehicles, traveling in opposite directions, and in strait (geodesic) lines. The astronauts, well aware they may never return to the blue planet, enter their respective capsules, and fasten themselves securely in the small quarters that will serve as home for the next few years.

 

There was a palpable air of excitement pre-launch about the notion that those chosen for the mission were at the cutting edge. This feeling evaporated inside the capsules when the scratchy voice echoed through the loudspeakers: “t minus 15.”

 

At the same time they could feel irregular harmonic oscillations as their heartbeats mix in with the rumbling sound of the cryogenic engines: “Good luck boys, and thank you both for accepting the responsibility of breaking down the barrier between fact and theory, between science and paradox.”

 

One of the astronauts became somewhat paranoid…all that was needed was a sense of direction. A thousand thoughts raced through his mind as he contemplated aborting his mission (he actually had a penchant for the steady state theory when in college and was now thinking of converting back).

 

But it was too late…the countdown had already begun, “we are go for launch:”

 

10…9…8…'spacetime must be flat' he thought out loud…

7…6…5…'the inverse Hubble constant must give Tu = 2/3Ho -1'…

4…3…'The age of the universe is Tu = 15 ± 2 Gyr based on the age of Galactic globular clusters at 14 Gyr plus 1 Gyr if Ho = 50 ± 2 as in Table 8.4 of Lecture 8 (Sandage 1993) and therefore Ho-1 = 19.5 Gyr.

 

It was comforting to know that the universe was older than the Earth…almost.

 

2…The other astronaut was quiet, concentrated, thinking only about his mission and that omega = 1. He had always been an avid supporter of big bang cosmology…but nevertheless felt a serious strain on the sphincter muscle as the engines started growling and kicked into high gear.

 

1…”We have booster ignition and liftoff of the first manned mission to increase and strengthen our cosmological awareness and to provide explicit information, facts, truths, and principles of universal nature learned through time travel to the most remote regions of our understanding.”

 

 

What happens?

 

CC

[coldcreation]

OK, Coldcreation will break the ice.

 

The question this thought experiment asks is simple, but the answer may not be.

 

What would happen, according to the standard model (the canonical hot big bang - cold dark matter universe), if two observers were to depart from earth in opposite directions faster than the speed of light? (Of course this is impossible, that's why it's a thought experiment).

 

The reason I ask is because recent developments have indicated that disagreements and inconsistencies in the numerical representation of the Hubble flow differ by a factor of two: some estimates reveal 50 km per second squared, while others are closer to 100 km. (A factor of two is like being unsure whether you are standing on one or two legs).

 

Have a pleasant trip! I hope you enjoy your flight.

 

 

CC

[arkain101]

In my thought experiment with my understanding of theory and of some of my own input a few exciting events could happen.

 

According to the theory of special relativity, with the time dialation if they exceeded the speed of light the universe would head off into the speed of infinty while they either had 0 time or even negetive time. The mission would fail because time would take a infinite course into the future around them, leaving them in the dust as it were.

 

If time dialation is affected in fact by the direction of motion through the field of space-time then along the way they would disover through data how fast our galaxy is moving in space. But however this seems false since there seems to only energy shooting about in different forms interacting with concentrated energy and there is no absolute rest but meerly comparison to surrounding objects.

 

But if time dialation didnt come into play then the ships would redshift drastically possibly turning the light coming at them into xray or gamma ray intensity energy. While the energy behind them lessened and lessened in intestity untill unvisible to thier nake eyes.

 

Possibly one could not exceed the speed of light because the light they travel towards would begin having wave lengths so short that it literally collapsed the energy into minimum wavelength, creating an equal and opposite reaction on any force that pushes the ship along forward. Now if they could deflect any electromagnetic energy from interacting with the matter that makes up their ship, maybe it would be possible for them to avoid the super redshift of the energy infront of them that could cause them major problem.. then allowing them to soar off faster than light.

 

I just thought of something that you dont really go anywhere in space but you meerly affect the light that interacts around you. The speed of light remains constant but the 'time' of the light must change in order to remain its constant towards you. The flex in time warps the intesiy of the wave length and energy, or possibly just the velocity.

For example once you reach the speed of light we can throw away the idea that you are actually moving anywhere. Now we can invision the energy coming towards the ship as the maximum shift as more energy, and the energy coming to the rear of the ship as the minimum redshift in energy. Meanwhile the fastest thing to push this ship would be light itself. So theoretically you would need an equal frequency of light pushing the ship forward as you would that is hitting the ship from its direction of travel, assuming in the same quantity, to sustain constant velocity, and you would need to exceed the frequency of energy coming at you to accelerate in that direction. Once the frequency or red shift had hit its maximum so would requirement of the pushing force of the frequency of the pushing lazer. So in effect if you reached .999C you would need gamma radiation pushing against the gamma radiatoin to maintain such and such .999C. But once the wave length is 0, the energy to acellerate it (aka feel a increase in speed) would require the same and actually stronger force than 0 wave length.

 

yah.. thats totally what happens. :)

[coldcreation]

yah.. thats totally what happens. :)

 

Yes arkian101, you are right, but if we keep going further, eventually we will get somewhere. True, what happens on the journey is important. The way I see it is like this:

 

All of a sudden a violent tremor is felt through both capsules. One of the astronauts radios back to home base: 'What the hell was that?' Houston has no idea what's going on but tries to reassure him nevertheless. It was to late. His sphincter, held tight up until then, had unwound…a momentary lapse of concentration, but there were more important things to worry about. The ships both vibrating radically were about to experience an ultra-luminescent-boom that would rock the vessels as they broke the light barrier. [Of course this is impossible, that's why it's a thought experiment].

 

Live communication with Houston was from then on impossible. The astronauts were on their own, invisible, locked behind a barrier, out of sight. Houston would only learn what was happening after the fact, with a time delay that would increase proportionally with distance. Ultimately, only the younger generation working at the Houston command and control center would learn about the fate of the expedition, about the very early universe.

 

Five minutes later they are moving much faster than the speed of light, going back in time, flying freely through a spars interstellar and intergalactic medium, and through an occasional cloud of photoionized hydrogen. They saw constellations they had never seen before, but otherwise everything seemed normal. The universe was indeed homogenous and isotropic in all directions: at least out to the distances that were visible.

 

What happens next?

 

CC

[coldcreation]

Still traveling in opposite directions from Earth, our astronauts are now crossing the expanse of virtually empty space between the Local Supercluster (home of the Milky Way) and its closest companion clusters.

 

The light from metal enriched galaxies appears blushifted as they burn by with mind-boggling velocities. Sporadically, upon looking through the window, they see old spiral galaxies with their wispy tendrils and compact entrails from up close on occasional fly-bys designed to pick up more speed, but for the most part the sky is black with puffs of smoke-like swirls. The photoelectric scanner measurements can hardly disentangle the contributing stellar types. The universe appears as they had seen it on the Hubble Space Telescope deep field plates. It is f__ cold (2.726 Kelvins) and dark.

 

Eventually their journey takes them through cosmic regions unattainable with our humble space telescopes, where the post-main sequence first-generation stellar SN explosion products were embellishing the environment with light elements - helium, lithium and beryllium - known as the recycling era.

 

A little further they traverse an epoch where the brief interlude of protogalaxy formation was underway: the so-called primeval galaxy phase-the pinnacle of cosmic evolution. In this outlying époque, stars and galaxies were forming out of initial density fluctuations.

 

Curiously enough, this epoch was not visible through our largest telescopes, though it should have been, according to predictions. As the voyage continues, the surrounding cosmic microwave background (CMB) becomes warmer and warmer. This looks like proof that the universe used to be a hot place. It is difficult to think of a more gloriously redundant, cosmologically correct bit of info: no matter how wrong it really is.

 

Something has changed...

 

CC

[CraigD]

Your [coldcreation’s] humble reader has been following the story, and now wants to make a naive guess at what comes next.

 

Since shortly after his bowl-quaking passage through the light-speed barrier, our astronaut has been venturing where truly no one has gone before – outside of the light-cone of human history. In short order – the ship’s propulsion showing no signs of slackening its counter-relativistic acceleration – he will be outside of the light-cone of the history of the universe according to the Big Bang theory – a point in space-time presumably about 13 billions years in the past.

 

Will he see photons from events predating that era? Will there be any such photons to see. Will he see (or be in!) a weird universe subject to different fundamental physical law than the one he left? Will he see incredible x-ray emissions of an impending Big Crunch? Will he see a steady universe, different perhaps in frequency of elements as detected by his spectroscope, but otherwise not that different than the one he left?

 

Being as this is coldcreation’s story, I expect he’ll see an ancient universe consistent with coldcreation’s Cold Creation theory of cosmology. Since my grasp of precisely what that would look like is, to put it kindly, shakey, I think I’ll have to wait to see.

 

(Clunky light-cone scribblings attached)

temp.bmp

[coldcreation]

Your [coldcreation’s] humble reader has been following the story, and now wants to make a naive guess at what comes next.

 

Since shortly after his bowl-quaking passage through the light-speed barrier, our astronaut has been venturing where truly no one has gone before – outside of the light-cone of human history. In short order – the ship’s propulsion showing no signs of slackening its counter-relativistic acceleration – he will be outside of the light-cone of the history of the universe according to the Big Bang theory – a point in space-time presumably about 13 billions years in the past.

 

Will he see photons from events predating that era? Will there be any such photons to see. Will he see (or be in!) a weird universe subject to different fundamental physical law than the one he left? Will he see incredible x-ray emissions of an impending Big Crunch? Will he see a steady universe, different perhaps in frequency of elements as detected by his spectroscope, but otherwise not that different than the one he left?

 

Being as this is coldcreation’s story, I expect he’ll see an ancient universe consistent with coldcreation’s Cold Creation theory of cosmology. Since my grasp of precisely what that would look like is, to put it kindly, shakey, I think I’ll have to wait to see.

 

(Clunky light-cone scribblings attached)

 

Hi hi hi, hmmmm, not bad,

 

Actually this though experiment is in reference to the standard model, not the Coldcreation universe. Indeed, we are going back in time in an expanding universe, as you correctly point out (no pun intended), to a point in spacetime.

 

So what happens on the way?, Well, Something has changed. The main galaxy locus has dispersed. There is degradation in the sharpness of images. A surprising fraction of the total light is scattering to radii greater than 30 arcsec. There is frequency modulation of detected photons, along with image crowding: Flux levels are so faint that galaxies appear to be very close to each other with respect to their diameters. The mean separation is only 3.6 arcsec. The “sea” of galaxies forms a lumpy background. The source distribution is a priori unknown. One astronaut modifies the input parameters of his onboard computer simulation to check the robustness of the conclusions. It looks very unpromising, to say the least. The other looks back to identify where the various factors of 1 + z came from. He takes into account the k-correction to stretch the bandwidth of the chosen rest-frame spectrum. Unfortunately, this doesn't solve the problem, since the noise from the sky background is a function of redshift. Now, everything is blueshifted to a much more intense shorter wavelength than calculations permit. Clearly, more information is needed.

 

The surprising thing is that such spectral shifts correspond to a look-back time of only a few cluster crossing-times. It is hard to see why such strong evolution happened so recently to so many clusters in synchronization. Was the universe younger than the objects in it? Critical processes of cluster dynamics were expected to have reached some kind of equilibrium long ago. Butcher and Oelmer conjecture (1978) had been founded on the similarity of blue galaxy numbers in high-redshift clusters. What gave?

 

CC