The valid question has always been "have decay rates really been constant for millions of year?" First of all, to say yes is ONLY an assumption, it is not scientific. It can in no way be proven. |
Care to test that assertion?
Supernova SN1987A, pulsars and the Oklo natural reactors tell us about Constant Constants:
Distance to SN1987A
Reference 1: The Distance to Supernova 1987a by Don Lindsay, Last modified: 25 June 2006, accessed 24JUN07:
quote:
At an earlier stage in its life, the star which exploded gave off material which formed a ring. Light from the supernova eventually bounced off of this ring, and about a year after we saw the explosion, we suddenly saw the ring.
Now, imagine a triangle. We know one of the angles - the angle, from here, between the supernova and the ring. And we know the length of one side, in years. From that, high school trigonometry gives us the lengths of the other two sides. The distance is 168,000 light years, Â± 3.5%.
A light-year is a measure of distance, specifically the distance light would travel in one earth year at the current speed of light. This is about 5.88 trillion mi. (9.46 trillion km) , so 168,000 light-years would be about 988,000 trillion (10^{12}) miles or ~9.88 x 10^{17} miles. How do we know this distance is not affected by a change in the speed of light?
Reference 2: Dave Matson: Young Earth: Additional Topics: Supernova, A6. The Distance to Supernova SN1987A and the Speed of Light, Last updated: Wednesday, 30-Nov-2005 17:06:12 CST, accessed 24JUN07
quote:
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.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 distance 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 distance that the second beam lags behind the first, a distance which will not 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.
Reference 3: SN1987A and The Antiquity of the Universe, by Todd S. Greene, originally written 3/16/2000, last revised 9/14/2000, accessed 24JUN07.
quote:
1. radius = 6.23 x 1012 km (see note 1 below) = 0.658 light-years
2. angle = 0.808 arcseconds (see note 1 below) = 0.000224 degrees
3. distance = 0.658 ly Ã· tan(0.000224)
4. distance = 0.658 ly Ã· 0.00000392
5. distance = 168,000 light-years
Note that this is independent of the speed of light, thus it cannot - alone - confirm the speed of light at the time of the nova, but it does confirm the stellar distance involved.
The next question is whether we can confirm that the speed of light was relatively constant during the time it took the light to travel from SN1987A to earth.
The Speed of Light
Back to ref 2:
quote:
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 mid1980s 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.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 ...
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 lightyear is the distance a beam of light, traveling at 186,000 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) t years after creation (t=0). The second function gives the distance (light-years) that the first beams of light have traveled since creation (since t=0).
V(t) = V0 e^^{(-Kt)}
S(t) = 1010(1 e^^{(-Kt)})
V0 = 28,615,783 (The initial velocity for light)
K = 0.00286158 (the decay rate parameter)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?
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.
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 A) took about 2149.7 years to reach Earth. At the time light beam A left the pulsar it was going 487.4686 times the speed of light. The next day (24 hours after light beam A left the pulsar) light beam B 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 186,000 miles per second.) Allowing for the continuing decay in velocity, we can calculate that light beam A is 1.336957 light-years ahead of light beam B. That lead distance is not going to change since both light beams will slow down together as the velocity of light decays.
When light beam A 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 A and B, 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!
Exactly 5 years after light beam A left the pulsar, light beam Y departs. It is traveling at 480.5436 times the speed of light. Twenty-four hours after its departure light beam Z 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 Y has a lead in distance over light beam Z of 1.318767 light-years. Once again, when light beam Y 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 Y and Z, appears in slow motion to us. We see things happening 481.7 times slower than the rate at which they actually occurred.
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!
Such time discrepancy has not been observed in any pulsar. Thus by two different methods we confirm the speed of light is constant within our ability to measure it for the time period covered by the travel of light from SN1987A to earth. This of course ALSO means that the minimum age of the universe was 168,000 years (+/- 3%) in 1987 (when the nova was observed) ... AND it confirms the age of the light coming from the nova is ~168,000 years, so that any observed phenomena that occurred during that nova would have occurred 168,000 years ago.
What else can we tell from the evidence? Radioactive decay was observed during the nova, so the question is whether it matches the decay rates today, or whether it was significantly different. We start with it being non-zero decay due to it being observed.
Decay Rates 168,000 years ago
Reference 4: Evidence about Constants Being the Same in the Distant Past, by Don Lindsay, Last modified: 27 December 1998, accessed 24JUN07.
quote:
One nice piece of evidence comes from Supernova 1987a, which was special because it was not very far away. Theory predicts that such a supernova would create about 0.1 solar masses of nickel-56, which is radioactive. Nickel-56 decays with a half-life of 6.1 days into cobalt-56, which in turn decays with a half-life of 77.1 days. Both kinds of decay give off very distinctive gamma rays. Analysis of the gamma rays from SN1987a showed mostly cobalt-56, exactly as predicted. And, the amount of those gamma rays died away with exactly the half-life of cobalt-56.
We've confirmed the distance and the steady speed of light for the duration of travel from SN1987A to earth, and now we have confirmed that decay at today's decay rates for Cobalt 56 occurred 168,000 years ago. Due to the physics involved you cannot have one isotope have the same rate of decay and another be different. In fact there are a lot of inter-related elements of physics, astronomy and geology.
Ref 4 again:
quote:
Another evidence is the natural nuclear reactor at Oklo, in Gabon. This reactor was actually just an unusually rich body of radioactive ore. So rich, in fact, that when it was formed, it approached critical mass. Studies of the unusual elements found there indicate that reactors acted the same two billion years ago as they do now. If the fine structure constant had been different by as little as one part in a million, the Oklo measurements should have detected that.Another evidence is in the light from distant galaxies. When you pass starlight through a prism, you can see spectral lines, which just means that there is an excess (or shortage) of light at specific frequencies. Certain atoms (or molecules or reactions) produce distinctive spectral lines. Modern physics has a solid theory for such things, and we can calculate the frequencies from fundamental constants. Therefore, if we look at a distant galaxy, we can tell if certain fundamental constants are different there. Most of the references below discuss this.
Other methods mentioned in the references:
- Searches for changes in the radius of Mercury, the Moon, and Mars. These would change because of changes in the strength of interactions within the materials that they are formed from.
- Searches for long term (secular) changes in the orbits of the moon and the earth, as measured by looking at such diverse phenomena as ancient solar eclipses and coral growth patterns.
- Ranging data for the distance from earth to Mars, using the Viking spacecraft.
- Data on the orbital motion of a binary pulsar PSR 1913+16.
- Observations of long-lived isotopes that decay by beta decay (Re 187, K 40, Rb 87) and comparisons to isotopes that decay by different mechanisms.
- Searches for differences in gravitational attraction between different elements.
- Absorption lines of quasars. These measure fine structure and hyperfine splittings.
- Laboratory searches for changes in the mass difference between the K0 meson and its antiparticle.
Non-physicists may be surprised that all of these things are interconnected. For example, the radioactive decay of some elements is governed by the strong force. So, a change in their decay rate implies a different binding energy. Energy curves space, so a different binding energy implies a change in the amount of gravity, and that implies a change in orbital motion.
If you followed that, I said that if a planet has been in the same orbit for a long time, then Uranium-235's radioactive decay rate has been unchanged for that same amount of time. And so on. Physics creates a huge web of connections between astronomy and geology. You may find something debatable about any one of these results. However, it is very hard to argue against a great many independent results, each of which fits into a connected web, and each of which places strong constraints on how fast change could be happening.
Reference 5: Oklo Fossil Reactors - When did these Natural Fossil Reactors start operating? by Curtin University of Technology, Last modified: 25 Oct 2005, accessed 11 Nov 2007:
quote:
Using a number of radioactive clocks the Oklo fossil reactors have been radioactively dated to be about 2000 million years old. The uranium in these reactors is thought to have come from the tiny amounts of uranium orginally scattered throughout the earth's crustal rocks during its formation.
The interesting thing here is that if decay was different back then so that the radioactive dates were wrong, that then the product of the nuclear reaction would have been different -- those reactions occurred because the decay rates were the same as now.
Secondly, it is completely in line with the scientific spirit to question and test to find out if there is any evidence to suggest that they havent been constant. |
And it is even more in line with the scientific spirit to provide evidence that invalidates concepts, such as providing evidence that invalidates the concept that decay rates have not changed.
So far we have (1) evidence that decay rates have not changed and (2) no evidence that decay rates have changed.
Enjoy.
Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)
we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.