9. Why Do People Not Believe that Evolution Happened? ==>
   9.3. Specious Arguments Against Evolution ==>
     9.3.2. Nature of specious arguments ==> Arguments of Last Resort ==> Speed of Light changed ==> Speed of Light is Constant


Young Earth Creationists claim that the stars are less than 6000 light years away. They "appear" to be older because the speed of light is much faster than the 186,000 miles/second in outer space.This article explains how it is impossible for the speed of light to have been anything other than what we observe today


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Distance to Supernova SN1987A and the Speed of Light<br>


by Dave Matson&nbsp;</https:></http:><br>


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When supernova SN1987A exploded, its light soon struck a ring of gas some

distance from the star and illuminated it. As viewed from Earth, the ring

appeared around the supernova about a year after it exploded. Its angular

size combined with the time it took for the ring to be illuminated after

SN1987A was first observed allows a direct, trigonometric calculation of

the distance to that supernova with an error of less than 5%. <br>


Oddly enough, if we use the older Newtonian physics (which most creationists

love because it allows them to play around with the speed of light) we find

that a change in the speed of light does not affect our calculations of the

distance to SN1987A! Gordon Davisson pointed out that interesting tidbit.



The distance is based on triangulation. The line from Earth to the supernova

is one side of the triangle and the line from Earth to the edge of the ring

is another leg. The third leg of this right triangle is the relatively short

distance from the supernova to the edge of its ring. Since the ring lit up

about a year after the supernova exploded, that means that a beam of light

coming directly from the supernova reached us a year before the beam of light

which was detoured via the ring. Let us assume that the distance of the ring

from the supernova is really 1 unit and that light presently travels 1 unit

per year. <br>


If there had been no change in the speed of light since the supernova exploded,

then the third leg of the triangle would be 1 unit in length, thus allowing

the calculation of the distance by elementary trigonometry (three angles

and one side are known). On the other hand, if the two light beams were originally

traveling, say three units per year, the second beam would initially lag

1/3 of a year behind the first as that's how long it would take to do the

ring detour. However, the <i>distance</i>that the second beam lags behind

the first beam is the same as before. As both beams were traveling the same

speed, the second beam fell behind the first by the length of the detour.

Thus, by measuring the <i>distance</i>that the second beam lags behind the

first, a distance which will <i>not</i>change when both light beams slow

down together, we get the true distance from the supernova to its ring. The

lag distance between the two beams, of course, is just their present velocity

multiplied by the difference in their arrival times. With the true distance

of the third leg of our triangle in hand, trigonometry gives us the correct

distance from Earth to the supernova. <br>


Consequently, supernova SN1987A is about 170,000 light-years from us (i.e.

997,800,000,000,000,000 miles) <i>whether or not</i> the speed of light has

slowed down. <br>


Still, the creationist has one ace of a sort remaining. Had the speed of light

slowed down, as often imagined by creationists who have not advanced beyond

Newtonian physics, the distance of SN1987A would still be 170,000 light-years

as indicated above. However, the /time/ that it would take for the light

to reach us need not be anywhere near 170,000 years. We might counter by

arguing that if the speed of light had changed then so would the decay rates

of cobalt-56 and cobalt-57, and since their decay rates have been observed

in SN1987A (and appear normal) that should settle it. After all, in observing

SN1987A we are seeing it as it was in the past. The decay rates of cobalt-56

and cobalt-57 haven't changed, so light hasn't slowed down. (The speed of

light is related to energy by E = mc<sup>2</sup>. Thus, if the speed of light

could somehow change, then energy would be affected. The end result would

also be a change in the radiometric decay rates.) <br>


Unfortunately, this argument is based on the assumption that we <i>are</i>

observing the correct decay rates of the cobalt on SN1987A. In fact, if the

speed of light had slowed down according to some reasonable curve, we would

be seeing a slow motion replay of reality. The farther away objects are the

greater the slow motion effect. The <i>actual</i> decay rates of the cobalt

in SN1987A would have been much faster than what we observe today by looking

at SN1987A even though we are, in effect, seeing into the past. That is,

we would be seeing a slow motion replay of the decay rates of the two cobalt

isotopes, and those observed rates might just <i>happen</i> to match the

actual decay rates we observe today on earth. It would merely <i>appear</i>

to us that no change had occurred. Does this sound confusing? If it doesn't

then you are ahead of me! I'm still trying to put the pieces together! <br>


To this one might say, "Get an education!" Relativity is central to modern

science and the speed of light is a fundamental constant. Light can't go

faster than about 186,282 miles a second and that's that. One could then

recite volumes of laboratory studies, experiments, and observations to impress

the reader with the power and reliability of special relativity. However,

that approach might seem rather dogmatic to someone lacking a good education

in the sciences. Thus, I will pretend that light once traveled much faster

than today (as might be imagined in Newtonian physics) and show that it still

won't help the young-earth creationist. <br>


Our first argument is based on a straightforward observation of pulsars. Pulsars

put out flashes at such precise intervals and clarity that only the rotation

of a small body can account for it (Chaisson and McMillan, 1993, p.498).

Indeed, the more precise pulsars keep much better time than even the atomic

clocks on Earth! In the mid-1980s a new class of pulsars, called millisecond

pulsars, were discovered which were rotating hundreds of times each second!

When a pulsar, which is a neutron star smaller than Manhattan Island with

a weight problem (about as heavy as our sun), spins that fast it is pretty

close to flying apart. Thus, in observing these millisecond pulsars, we are

not seeing a slow motion replay as that would imply an actual spin rate which

would have destroyed those pulsars. We couldn't observe them spinning that

fast if light was slowing down. Consequently, we can dispense with the claim

that the light coming from SN1987A might have slowed down. Therefore, the

decay rates observed for cobalt-56 and cobalt-57 were the actual decay rates.



A more quantitative argument can also be advanced for those who need the details.

Suppose that light is slowing down according to some exponential decay curve.

An exponential decay curve is one of Mother Nature's favorites. It describes

radioactive decay and a host of other observations. If the speed of light

were really slowing down, then an exponential decay curve would be a reasonable

curve to start our investigation with. Later, we will be able to draw some

general conclusions which apply to almost any curve, including those favored

by creationist Barry Setterfield. <br>


We want the light in our model to start fast enough so that the most distant

objects in the universe, say 10 billion light-years away, will be visible

today. That is, the light must travel 10 billion light-years in the 6000

years which creationists allow for the Earth's age. (A light-year is the

distance a beam of light, traveling at 186,282 miles per second, covers in

one year.) Furthermore, the speed of light must decay at a rate which will

reduce it to its present value after 6000 years. Upon applying these constraints

to all possible exponential decay curves, and after doing a little calculus,

we wind up with two nonlinear equations in two variables. After solving those

equations by computer, we get the following functions for velocity and distance.

The first function gives the velocity of light (light-years per year) <i>t</i>

years after creation (<i>t</i>=0). The second function gives the distance

(light-years) that the first beams of light have traveled since creation (since

t=0). <br>



1. V(t) = V<sub>0</sub> e<sup>-Kt</sup> , and<br>

2. &nbsp;S(t) = 10<sup>10</sup>*(1 - e<sup>-Kt</sup>) , with</b><br>


V<sub>0</sub> = 28,615,783 (the initial velocity for light in units of present

light years per year, equivalent to the factor by which the present speed

of light was larger at creation, t = 0) <br>

K = 0.0028615783 =&nbsp;V<sub>0</sub>/10<sup>10</sup> (the decay rate parameter,

units of inverse years) <br>


With these equations in hand, it can be shown that if light is slowing down

then equal intervals of time in distant space will be seen on Earth as unequal

intervals of time. That's our test for determining if light has slowed down.

But, where can we find a natural, reliable clock in distant space with which

to do the test? <br>


As it turns out, Mother Nature has supplied some of the best clocks around.

They are the pulsars. Pulsars keep time like the Earth does, by rotating

smoothly, only they do it much better because they are much smaller and vastly

heavier. The heavier a spinning top is the less any outside forces can affect

it. Many pulsars rotate hundreds of times per second! And they keep incredibly

precise time. Thus, we can observe how long it takes a pulsar to make 100

rotations and compare that figure to another observation five years later.

Thus, we can put the above creationist model to the test. Of course, in order

to interpret the results properly, we need to have some idea of how much

change to expect according to the above creationist model. That calculation

is our next step. <br>


Let's start by considering a pulsar which is 170,000 light-years away, which

would be as far away as SN1987A. Certainly, we can see pulsars at that distance

easily enough. In our creationist model, due to the initial high velocity

of light, the light now arriving from our pulsar (light beam <i>A</i>) took

about 2149.7 years to reach Earth. At the time light beam <i>A</i> left the

pulsar it was going 487.4686 times the speed of light. The next day (24 hours

after light beam <i>A</i> left the pulsar) light beam <i>B</i> leaves; it

leaves at 487.4648 times the speed of light. As you can see, the velocity

of light has already decayed a small amount. (I shall reserve the expression

"speed of light" for the true speed of light which is about 186,282 miles

per second.) Allowing for the continuing decay in velocity, we can calculate

that light beam <i>A</i>is 1.336957 light-years ahead of light beam <i>B</i>.

That lead distance is not going to change since both light beams will slow

down together as the velocity of light decays. <br>


When light beam <i>A</i> reaches the Earth, and light is now going its normal

speed, that lead distance translates into 1.336957 years. Thus, the one-day

interval on our pulsar, the actual time between the departures of light beams

<i>A</i> and <i>B</i>, wrongly appears to us as more than a year! Upon looking

at our pulsar, which is 170,000 light-years away, we are not only seeing

2149.7 years into the past but are seeing things occur 488.3 times more slowly

than they really are! <br>


Exactly 5 years after light beam <i>A</i> left the pulsar, light beam <i>Y</i>

departs. It is traveling at 480.5436 times the speed of light. Twenty-four

hours after its departure light beam <i>Z</i> leaves the pulsar. It is traveling

at 480.5398 times the speed of light. Making due allowances for the continual

slowing down of the light, we can calculate that light beam <i>Y</i> has

a lead in distance over light beam <i>Z</i> of 1.318767 light-years. Once

again, when light beam <i>Y</i> reached Earth, when the velocity of light

had become frozen at its present value, that distance translates into years.

Thus, a day on the pulsar, the one defined by light beams <i>Y</i> and <i>Z</i>,

appears in slow motion to us. We see things happening 481.7 times slower

than the rate at which they actually occurred. <br>


Therefore, if the above creationist model is correct, we should see a difference

in time for the above two identical intervals, a difference which amounts

to about 1.3%. Of course, the above calculations could be redone with much

shorter intervals without affecting the 1.3% figure, being that the perceived

slowdown is essentially the same for the smaller intervals within one day.

As a result, an astronomer need only measure the spin of a number of pulsars

over a few years to get definitive results. Pulsars keep such accurate time

that a 1.3% difference--even after hundreds of years--would stand out like

a giant redwood in a Kansas wheat field! <br>


So, what are the results of this definitive test? Many pulsars have been observed

which show nothing remotely close to a 1% change in their rotation rates

over a five year period. Although we have technically disproved only the

above model, we have, nevertheless, thrown a monkey wrench into the machinery

for decaying lightspeed. Every such scenario must have the slow motion effect

described above. Furthermore, the slow motion effect is directly related

to how fast the light is moving. If a model requires light in the past to

move one hundred times faster than observed today, then, at least for some

interval of time measured in that part of space, we would observe things

moving one hundred times as slow. <br>


That's the fatal point which no choice of light-velocity decay curve can wholly

remedy. The creationist model, in order to be useful, must start with a high

velocity for light so that objects ten billion light-years away <i>can</i>

be seen in a universe a mere 6000 years old. Consequently, such a universe

must appear, in general, to be slowing down more and more the further we

look into the depths of space. And the further we look, in general, the more

dramatic the perceived slowdown should be. <br>


It might seem that if we started out with a fantastically high velocity for

light, which then decayed precipitously, we could reduce the problems. Certainly,

that would produce a light-velocity decay curve with near normal velocities

for most of the years between t=0 and t=6000. However, the effect would be

to move the departure time of light beam <i>A</i> (in the above model) closer

to the creation time and to jack up its speed. Thus, the slow motion factor

would be even worse than the model we just examined! On the other extreme,

by abandoning an exponential decay curve, one can get the initial velocity

down to about 1.6 million light-years per year. But alas! The velocity of

light beam <i>A</i> is now 1.6 million light-years per year! We've gone from

the frying pan into the fire. <br>


The problem, from a graphical point of view, is that we have a certain amount

of obligatory area under the velocitytime curve which must be distributed

in some way. That area represents the 10 billion light-years of space which

our initial light beams must cross in 6000 years. No matter where you put

that area, no matter how you poke or shape it, you have a problem. <br>


The big question, then, is whether our general observations of the universe

fit such models. Do we, for example, observe pulsars spinning slower and

slower the further away they are? Do the rotation of galaxies, as determined

from the Doppler effect, grind to a near halt in the more remote regions

of space? Do dust clouds seem to collapse more slowly the farther away they

are? Do the closer novas and supernovas explode, on the whole, more quickly

than the more remote ones? Do galaxies appear to be traveling any slower

the farther away they are? The answer is no. <br>


The alternative, if these light-velocity decay models are to be salvaged,

is that the more distant the object the faster it is moving. Thus, we would

have the illusion of seeing normal rates prevail everywhere, the slow motion

factor being cancelled by objects which are moving, in truth, faster and

faster the further we look into the depths of space. However, there is a

limit to how fast some things can go. Millisecond pulsars are already close

to flying apart. Their spin rates are no illusion! The distant galaxies,

if they were really rotating millions of times faster a few thousand years

ago, would have flown apart. We are led into absurdity. There is no reason,

for example, for believing that the distance of a gas cloud from us dictates

how fast it will collapse! We have no reason to believe that distant galaxies

once traveled millions of times faster than their observed rates. Had they

done so, they would surely have broken out of the great clusters of galaxies

which are bound by gravity. Their distribution today would have been more

or less random. <br>


Light, itself, would have behaved differently at different speeds. The higher

the speed the more blueshifted, the more energetic it would be. Certain wavelengths

of light, for example, have the power to penetrate the galactic dust, thus

allowing us to see events going on in the core of our galaxy. If the wavelength

of such light was merely an illusion produced by the slow motion effect,

if those light waves actually existed at shorter frequencies back then, they

would have been absorbed or scattered differently by the galactic dust. That

is to say, astronomers would not see a logical correspondence between the

wavelengths they observe and their known properties. In the above example,

we might not see the galactic core at all by using the preferred wavelength

for dust penetration! Needless to say, astronomers don't have that problem.



Our conclusion, then, is that any model which would drive us to such views

is bankrupt. We can forget about those claims that light traveled much faster

in the past. <br>


Once it's clear that the light-velocity decay models are bankrupt, not only

with respect to modern science but even within Newtonian physics, then there

is only one reasonable conclusion. The light coming from distant stars and

galaxies have not only traveled immense distances but have spanned ages as

well. In particular, the fact that supernova SN1987A is around 170,000 light-years

distant means that we are seeing an event which is around 170,000 years old.



A few creationists have argued that the universe really isn't that big. In

particular, Slusher, working for the Institute for Creation Research, argued

in 1980 that the universe is based on a Riemannian space which allowed no

point to be more than 15.71 light-years away. The great distances observed

would be an illusion based on mistaking the Riemannian space for Euclidean

space. <br>


This model, however, requires that the distance to supernova SN1987A be measured

at less than 15.71 light-years in contradiction to the 170,000 light-years

actually measured. Unexploded versions of SN1987A would be seen at the same

time, one of them being at a perceived distance of 170,000 light-years! A

few decades later, the light from the explosion would circle around again,

thus causing us to see SN1987A explode all over again! This is madness, not

science! See Strahler (1987, pp.114-116) for a thorough debunking of this

Riemannian space nonsense. (George Friedrich Bernhard Riemann, 1826-1866,

was a German mathematician whose work on curved space proved helpful to Einstein,

but not with the absurd radius of curvature assigned by Slusher!) <br>


Yet another idea, advanced by Henry Morris and others, is that star light

was created /in situ/ during the Genesis creation week. However, we have

now left the realm of science for theology. There is no scientific way to

separate star light from its origin in a star. Not only is it theology, but

it's bad theology. God creates a universe which forces him to be a deceiver!

It goes beyond the need for any reasonable appearance of age as a result

of functionality. There is no need, for example, to see supernovae explode

before their time. An observer would ultimately see the supernova leap back

together and explode all over again when the light from the real explosion

finally arrived! It makes God out to be an idiot. <br>


When the smoke blown about finally drifts away and the debate hall falls silent,

the young-earth creationist finds himself back on square one. He is looking

at stars many millions of light-years away, stars putting out light which

takes <i>many millions</i> of years to reach us! Attempts to speed up the

velocity of light or to shrink down the universe have come to naught. What

does remain is the old age of our universe. <br>

<hr width="100%" size="2"><small><i>Last updated: Friday, 13-Sep-2002 10:47:58


Copyright &copy; 1995 Dave E. Matson.<br>

Originally appeared <a