Article - Why Remote Galaxies are Lost to Red Shift.

On the journey to explain Notches statement about red shift, let's start with Pink Floyd. Specifically, the Dark Side of the Moon album cover.


Figure 1. Pink Floyd's Darkside of the Moon Cover/Demonstration of splitting sunlight into it's spectrum using a glass prism. 

Direct the suns rays at a prism and look very closely at the spectrum produced. Do you see a continuous, uninterupted rainbow of colours? Nope! Just as William Wollaston noticed in 1802, you'll notice some rather obvious black lines at specific frequencies.


Figure 2. Solar spectrum showing black lines, reflecting missing wavelengths.

Now, so you don't fall asleep we need to skip past a large chunk of the history of science and simply state that each black "absoption" line in the sun's spectrum relates to a specific electron energy level transition in a specific chemical element. 

To simplify this, look at the absorption spectrum for just one element: simplest chemical element: hydrogen (which also happens to make up 70% of the mass of the sun)


Figure 3. Hydrogen absorption spectrum

To help later on, look to the right hand side of Fig.3, the presence of an absoption line at 656 nanometres indicates that Hydrogen is present (its named H-Alpha).

So far so good. Now move your focus from our Sun to distant galaxies. 8 or 9 of them are visible with the naked eye, go out and have a look! Or, checkout images like the Hubble Deep Field image below, to help realize that there are an awful lot of galaxies out there. In fact, more than anyone imagined until recently.


Figure 4. Typical image from Hubble Deep Field indicating just how many bloomin' galaxies are out there.

Now then, as galaxy is a collection of billions of stars that are mainly made of hydrogen, you should expect to see the same absorption lines for hydrogen in a spectrum from a galaxy. So what do you actually see? For instance, is the H-Alpha line there? Well, it's there... but it's not in the right place: it has been shifted to towards the red end of the spectrum. Hence the term Redshift. Indeed, all spectral lines have been redshifted. 


Figure 5. Example spectrum showing spectral lines (top), that are red shifted (bottom)

Every single galaxy you observe like this have been redshifted Very strange! The question is, why? What phenomena could possibly be moving light to the red (less energetic) end of the spectrum.

And this is where we need to speak about emergency vehicles with their sirens turned on that are speeding towards you and then speeding away from you (Nee-Naw-Nee-Naw!). As the vehicle passes you, and begins to move away from you, the pitch of it's siren gets lower. In other words, as the origin of the sound is moving away, the apparent wavelength of the sound is lengthened. With sound waves, this means a lower pitch.


Figure 6. Dopper Effect in sound waves, in action!

Switching from sound waves back to light. When a light source is moving away from you, its wavelength again is stretched. i.e. it's colour is changed. You know where this is going.... it's been redshifted.


Figure 7. Dopper Effect in electromagnetic radiation. That's light, to you and me.

Now back to the universe. If every single galaxy we look at in the sky has been redshifted, what does it mean? It means Every single galaxy is moving away from us. <gulp>

To visualize this, folks normally talk about balloons now. Imagine our normal 3 spacial dimensions are represented by the surface of a balloon. Have some fun, draw galaxies on the surface of a balloon. Start blowing the balloon up. Measure the distances between drawn galaxies as you blow the balloon up uniformly. The distances between every galaxy on the balloon surface get larger as the balloon inflates.


Figure 8. Physics teachers like to draw spiral galaxies on a balloon. (Weird people, I know.)

Back to the universe again... distances between all galaxies are increasy? This means our universe isinflating. You know this already, from talk of the big bang. And for once, I'm not referring to my favorite TV Show. However, the energy involved in the big bang is not sufficient to explain the redshifts and rate of inflation that we see from observation. And this is where things are about to get weirder...

Not only are all galaxies flying away from each other, they are accelerating away from each other. That needs repeating for dramatic emphasis: Everything is accelerating away from everything else! To explain this, clever folks had to invent dark energy, and dark energy inflation but that.... is another story. For us future 0x10C players and most importantly: even without an explanatory hypothesis, the observation stands that all galaxies are excellerating away from each other.

Now we need to get back to 0x10C... What does this mean for our game? 

Well we all know it's set in the year 281,474,976,712,644 AD. I'm gonna write that as 3x10^15 years from now on, because 281,474,976,712,644 is a slightly unwieldy number! 

The current age of the universe is 1.4x10^9 years. The game is set in a time where the universe is 3x10^15/1.4*10^9 times older than the present. Which is 2x10^6, i.e. 2,000,000. To clarify: the age of the universe in the 0x10C game is 2 million times greater than the current age of the universe!

Let's recap now on the 1.4x10^9 year history of the universe so far, with a great graphic fromDarkMatterDarkEnergy.com


Figure 9. A graphical representation of the history of the universe. Time runs from zero at the big bang on the left, to the present day on the right. The vertical width of the graphic represents the size of the universe. So after the big bang comes the early inflation, a dark period prior to star formation beginning, then a long period of gravity driving clumpy galactic cluster formation. Followed by dark energy taking hold and beginning the observed acceleration of distance between galaxies.

We're about to get to the point of the article. Breath a sign of relief, you're nearly there!

In the game, dark energy inflation has been inflating the universe for 2 million times more than it's current age! Figure 9 is now 2 million times wide! Galaxies are now an unimaginably huge distance away from each other. Hence the reason Notch said 'Remote Galaxies are forever lost to Red Shift'. There will be no travelling between galaxies.

Next Question Please! 

By deouro