Lawson's Learning Object

1. Lawson Cofield
Redshift & its Implications
As one of your less technically inclined classmates, I hopeI can hold your
attention for a few moments withoutflashy images or elaborate diagrams. If you
stick with me for a few minutes, we’ll delve into Earth’s place in the cosmos, the
ultimate fate of the universe, and hopefully some physics. Today I wantto share
with you one of the more interesting applications of our understanding of light
waves. This application is the observation and study of cosmologicalredshift. As
you probably already know fromthe prereading, the red part of the visible light
spectrumhas a longer wavelength than any other. As you may also know, objects
moving away fromyou havetheir wavelengths stretched out, and elongated
relative to the viewer (or listener). In astronomy, theimplications of this are that
objects moving away from earth havetheir light spectrumwavelengths stretched
out and elongated, making them appear red from the perspective of an observer
on earth. This shift towards thered end of the spectrumis called Redshift.
So what can we do withthis knowledge? Using our knowledgeof how
wavelengths and the direction of velocity interact (relative to the observer), we
can determine whether objects are moving towards, or away fromearth. Objects
moving away fromearth are shifted towards the red end of the spectrum, while
objects moving towards earth are shifted towards the blue end of the spectrum.
This gives us a much richer understanding of our place in the cosmos, as wecan
determine with a much greater degree of accuracy which direction we are
travelling in and which direction things around us our travelling in.
So what did we discover whenwe started observing the directional velocity of
cosmological objects aroundus? What we discovered was entirely unexpected.
As we began observing Redshift between ourselves and thousands of
cosmologicalobjects, one thing quickly became apparent; velocity away from us
increases withdistance. Thatis, the further an object is fromearth, the faster
away fromearth it is moving. This discovery had profound implications. The firstis

2. that space is undeniably expanding, and the second is the expansion of space
appears to be accelerating.
But what could be causing the expansionof space toaccelerate? This is a
question that currentastronomy cannotanswer, and as a result wecall this
strangeand unknown force: Dark Energy.
If space is expanding at an accelerating rate, does that meanit will expand
forever? Thecommonly accepted theory in astronomy rightnow, is that yes, the
universewill continue to expand forever. This theory is called the Big Rip or the
Big Freeze theory. Theidea being that eventually, the universewill expand until
no 2 subatomic particles can interact with each other. This means there will be no
life, no stars, no light sources, no heat, and pretty much nothing but matter
scattered millions of light years apart. This is, however, a widely debated topic in
astronomy and could change as our knowledge of physics grows stronger!
How did we extrapolate all of that from a simple wave phenomenon? Using our
knowledgeof redshiftcombined with our knowledge of star light emission, which
allows us to differentiate naturally red stars fromstars travelling away fromearth;
we were able to develop a formula for the correlation between distance and
expansion velocity. This formula is one of the fundamental formulae behind the
science of predicting the future of our cosmos. Likemost things in physics, our
formulae lead us to a greater understanding than empirical observation could
ever serveto give us.
Since you made it this far, here’s aneat picture of the expanding universe. Now
you can look at this and contemplate the inevitable freeze-deathof our sunny
universe. Physics is really great 