Freethought & Rationalism Archive

Tom Sawyer · 08-02-2002, 09:13 AM

OK, I just had a very strange discussion with a xian friend of mine who said that evolution and the age of the universe cannot be proven to be correct.

His argument went like this: we have only been measuring the speed of light for some two hundred years. The fact that there has not been any measurable change in its speed over that period does not mean that it has been changing over a long period of a few thousand years and the rate of change is so slow that we have not been able to record any difference in it over the period we've been observing it. When we see things that we measure at billions of light-years away does not mean that they are actually that far away, just that because the constant speed of light we've been using in those measurments has been changing over time, so the measurments are off and they're actually much closer.

Here's something he sent to back up his claim:

Quote:

What about the slowing and stopping of light?
There have been a number of recent reports in scientific journals about variations on the speed of light. Last year, we posted a brief response by physicist Dr Russell Humphreys to experimental results allegedly showing information transmitted faster than the speed of light in a vacuum (called c, = 300,000 km/sec = 186,000 miles/sec). There have also been reports about the opposite effect-markedly slowing down light itself.

Two years ago, a team led by Dr Lene Vestergaard Hau of Harvard University slowed light to just 17 m/s (38 mph) in a cloud of ultracold (only about a millionth of a degree above absolute zero) sodium atoms.1,2 This cloud was a special phase of matter called a Bose-Einstein condensate, where all the atoms have collapsed to the same quantum state. Another �coupling� laser beam, perpendicular to the main light and with a different polarization, split a single atomic absorption level into two, which cancelled each other out by destructive quantum interference. This cancellation of absorption produced the phenomenon of electromagnetically induced transparency.2

A number of enquirers asked if this experiment was significant for distant starlight travel time or c-decay theories. We pointed out that that light is always slowed down in matter, because it is constantly absorbed and re-emitted-the light is focused on the retina in your eye precisely because the lens and cornea slow down the light by about 30%. Many people need an outside lens which works on the same principle. However, this experiment has little to do with cosmology, because it�s the speed in a vacuum that counts for distant starlight travel time and for anything to do with c-decay theories. Einstein�s special theory of relativity states that light�s speed in a vacuum is constant. If anything, postulating that light had to travel slowly through a Bose-Einstein condensate would make the universe even older. [We do have answers, though-see How can we see distant stars in a young Universe?]

Now, Dr Hau3,4 and another team led by Dr Ronald Walsworth and Dr Mikhail Lukin of the Harvard-Smithsonian Center for Astrophysics independently announced that they have slowed-and stopped-light.5 This time, Dr Hau�s team turned off the coupling beam before the probe pulse had emerged, so the pulse ground to a halt. When the coupling beam was turned back on, the probe pulse re-emerged. What happened was that the information in the probe pulse was stored in a �quantum coherence pattern� imprinted on the atoms, and when the coupling beam was turned on, this information was �read out� and converted into photons again. They could even chop up the original pulse into three, or �read out� such that the re-emerging pulse was shorter and more intense.4 Dr Hau�s team claim that this system could be used in quantum information processing. [Note added 26 July 2001: this is even more plausible since researchers led by Alexey Turukhin of the Massachusetts Institute of Technology have demonstrated a similar effect in a solid. They slowed light to 45 m/s in a crystal of yttrium silicate doped with praseodymium, and the results were presented to the Quantum Electronics and Laser Science Conference in Baltimore in May.6]

Once again, this has nothing to do with creationist cosmology, but it�s still fascinating science!7 The nuclear physicist Dr Humphreys reinforced this point during a recent interview on AnswersLIVE: ( Click here to listen to the full broadcast)

�� the problem is how to do the reverse-how to speed it up faster than its speed in a vacuum, or its speed in air [which] is about the same as that in a vacuum. No one�s done that. I don�t think that�s necessarily impossible either-it�s just you would have to do something different than what people are doing now.�

Also in terms of carbon dating of fossils, he said that that is not necessarily accurate, either as the rate of carbon decay has not necessarily been constant either and things that we measure at millions of years old are actually only a few thousand, it's just that the constant used in our measurement is not actually a constant.

Here's the link he sent to back up his theory:

<a href="http://www.answersingenesis.org/home/area/magazines/tj/v14n1_radioact.asp" target="_blank">Radioactive Decay Rate</a>

Basically, he didn't say that those things were so, just that they could be so, so that made evolution no more than just one more theory. My shocked answer of "Oh my God, how dumb are you?" didn't have the desired effect of disabusing him of this notion and do any of the physicists or geologists out there have any hard facts (preferably with links to back them up) to dispute his wierdo pseudi-science with?

I was a bit too stunned to be able to give an intelligent response.

Axiom of Choice · 08-02-2002, 09:26 AM

I'm sure someone with more time will give a better response. I also seem to remember some good discussion of this on talkorigins, so you might want to check that out. However, in a nutshell, if the speed of light has been changing fast enough so that the 10 billion year old light has REALLY only been traveling 6000 years, then with modern technology we could measure that change today. In addition, if you assume that the speed of light is changing, you cannot reconcile that with experimental observations of pulsars (and probably some other objects).

Also, with radioactice decay, if the decay rates were higher in the past so that things seem older today based on the modern "slow" decay, then the earth would still be molten from the 5 billion years of energy released over a few thousand (assuming this person is trying to make the YEC arguement).

If this person starts saying things like: "well god could make the energy dissappear" or the like, well, they have completely discarded any pretense of a scientific explanation, not that they really had one to begin with. Yeah, sure if god existed, it could do this, that or anything else. It could make the universe appear very old, but how could you tell? How is that different than if I claim my cat created the universe last Tuesday because she wanted some milk?

Coragyps · 08-02-2002, 11:18 AM

The variation in light intensity from a supernova follows the same path no matter how far away the supernova is. The decline in light intensity is mostly due to gamma rays from the decay of cobalt-56, with an 80-day half life. If the speed of light was faster in the past, this half-life would have also been different: the speed of light enters into the equations having to do with decay. So as far as we can see, a few billions of light years, the speed of light doesn't change.

A non-mathematical approach to debunking this sort of malarky that even YEC folks can understand goes like this:
Nearby galaxies look large, and when they have supernovae in them, they can sometimes be bright enough to see with the naked eye. Similar-shaped galaxies that are thought to be far away, based on red shift, are dim, look small, and have supernovae that require large telescopes to detect. Now let us assume for the moment that this second group is actually nearby, but some deity-driven phenomenon just makes them appear distant: the stars in them are smaller, and explode more weakly, perhaps.

Now, how does that assumption differ from this scenario:
You set up an observatory on Interstate Highway 40 west of Amarillo, Texas, so that you can watch semitrailer trucks recede into the west. You have an unobstructed view of twelve miles of road. Your observations indicate that trucks that have just passed your observatory have bright taillights that are well-separated (in the apparent angular sense - you could measure the separation if you wanted too.) Other trucke appear to have dimmer taillights much closer together, and still others have very dim ones that can only be seen individually with binoculars.
Now which is the more plausible explanation for these observations:
A) Semis of approximately equal size are at various distances from you, and the laws of physics and optics govern how bright and far apart their taillights appear to you
or B)
the trucks are all nearby, but the ones that appear to be largest are the only full-sized ones. The second group are all Tonkas (with battery-operated taillights) and the third group Matchbox brand toy trucks. And with time, group #1 morphs into #2 and then #3.

I prefer B.

[ August 02, 2002: Message edited by: Coragyps ]

Abacus · 08-02-2002, 11:34 AM

Quote:

Originally posted by Coragyps:
I prefer B.

When did you become a creationist?

[ August 02, 2002: Message edited by: Random Number Generator ]

MortalWombat · 08-02-2002, 12:28 PM

<a href="http://www.talkorigins.org/faqs/c-decay.html" target="_blank">The Decay of c-decay</a>

<a href="http://www.infidels.org/library/modern/dave_matson/young-earth/additional_topics/supernova.html" target="_blank">The Distance to Supernova SN1987A and the Speed of Light</a>

Coragyps · 08-02-2002, 12:34 PM

I didn't say I believe B. I I just like Tonka trucks.

BTW, does anyone have the citation for some astronomy paper where they obtained a trigonometric measurement of 28 million LY to the rotating disk of some galaxy? It was on the Very Large Array, IIRC, and within the last couple of years.....

[ August 02, 2002: Message edited by: Coragyps ]

Tom Sawyer · 08-02-2002, 01:35 PM

Thank you everybody.

I've emailed him the links you've provided and he's going to look at them over the weekend and we're going to discuss it more on Monday. I'll keep you updated on how it goes.

I've also got a few arguments of my own to use as well, I was just a bit stunned when he came up with the argument - I'd never met a Young Earth guy in the flesh before and it threw me for a loop. He's a vey intelligent guy and programs computers beside me and I didn't expect something like that out of someone like him.

Autonemesis · 08-02-2002, 01:38 PM

A trigonometric distance measurement to another galaxy sounds like you have misremembered something else you read. The proposed Square Kilometer Array is expected to be able to measure parallax distances to SiO masers in the nearby Magellanic clouds (~100,000ly). The SKA will be able to use intergalactic scintillation to achieve an angular resolution of .0001 arcseconds. To measure parallax to distances much farther than that will require an array with space-bourne elements. You're talking nanoarcseconds.

wdog · 08-04-2002, 04:52 AM

Quote:

His argument went like this: we have only been measuring the speed of light for some two hundred years. The fact that there has not been any measurable change in its speed over that period does not mean that it has been changing over a long period of a few thousand years and the rate of change is so slow that we have not been able to record any difference in it over the period we've been observing it. When we see things that we measure at billions of light-years away does not mean that they are actually that far away, just that because the constant speed of light we've been using in those measurments has been changing over time, so the measurments are off and they're actually much closer.

the experiments with greatly slowed light are done under very specialized conditions in the laboratory (didn't he understand his own post?). there is no evidence that these special conditions are present in the interstellar medium to any great degree that would affect the time of flight light travel. yes there is matter in the interstellar medium, but that has already been taken into account by astronomers. this claim is completely without merit.

this little note from the post is a good one

Quote:

[We do have answers, though-see How can we see distant stars in a young Universe?]

This whole article is about slowing down light (in matter of course) but to see distant stars in a young universe one would need to speed it up. Another case of creationist superficial understanding of real science followed by a leap to an unsupported conclusion.

the carbon dating problem has been addressed in other threads, I suggest you do a search.

Finally tell this guy that saying "it could have been" is a far cry from having evidence that it is really a plausible scenario. Anything at all "could have been" if my standard of proof is very low.

Starboy · 08-04-2002, 09:51 AM

The speed of light is connected to the prediction of atomic spectra such that if it were changing over time then atomic spectra would also change depending on distance. The only difference in spectra detected that I am aware of is the red shift.

The idea that physical constants could be changing over time is not a new one. IIRC there are experiments that have looked for it and found nothing.

I am aware of changes in the measured values of physical constants, but these are due to improvements in experimental apparatus and not any actual change.

Starboy

[ August 04, 2002: Message edited by: Starboy ]

08-02-2002, 12:34 PM	#6
Coragyps Veteran Join Date: Aug 2001 Location: Snyder,Texas,USA Posts: 4,411	I didn't say I believe B. I I just like Tonka trucks. BTW, does anyone have the citation for some astronomy paper where they obtained a trigonometric measurement of 28 million LY to the rotating disk of some galaxy? It was on the Very Large Array, IIRC, and within the last couple of years..... [ August 02, 2002: Message edited by: Coragyps ]</p>

08-04-2002, 09:51 AM	#10
Starboy Banned Join Date: Jun 2002 Location: Tallahassee, FL Reality Adventurer Posts: 5,276	The speed of light is connected to the prediction of atomic spectra such that if it were changing over time then atomic spectra would also change depending on distance. The only difference in spectra detected that I am aware of is the red shift. The idea that physical constants could be changing over time is not a new one. IIRC there are experiments that have looked for it and found nothing. I am aware of changes in the measured values of physical constants, but these are due to improvements in experimental apparatus and not any actual change. Starboy [ August 04, 2002: Message edited by: Starboy ]</p>

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08-02-2002, 09:26 AM	#2
Axiom of Choice Junior Member Join Date: Mar 2002 Location: Ohio (sigh) Posts: 14	I'm sure someone with more time will give a better response. I also seem to remember some good discussion of this on talkorigins, so you might want to check that out. However, in a nutshell, if the speed of light has been changing fast enough so that the 10 billion year old light has REALLY only been traveling 6000 years, then with modern technology we could measure that change today. In addition, if you assume that the speed of light is changing, you cannot reconcile that with experimental observations of pulsars (and probably some other objects). Also, with radioactice decay, if the decay rates were higher in the past so that things seem older today based on the modern "slow" decay, then the earth would still be molten from the 5 billion years of energy released over a few thousand (assuming this person is trying to make the YEC arguement). If this person starts saying things like: "well god could make the energy dissappear" or the like, well, they have completely discarded any pretense of a scientific explanation, not that they really had one to begin with. Yeah, sure if god existed, it could do this, that or anything else. It could make the universe appear very old, but how could you tell? How is that different than if I claim my cat created the universe last Tuesday because she wanted some milk?

08-02-2002, 11:18 AM	#3
Coragyps Veteran Join Date: Aug 2001 Location: Snyder,Texas,USA Posts: 4,411	The variation in light intensity from a supernova follows the same path no matter how far away the supernova is. The decline in light intensity is mostly due to gamma rays from the decay of cobalt-56, with an 80-day half life. If the speed of light was faster in the past, this half-life would have also been different: the speed of light enters into the equations having to do with decay. So as far as we can see, a few billions of light years, the speed of light doesn't change. A non-mathematical approach to debunking this sort of malarky that even YEC folks can understand goes like this: Nearby galaxies look large, and when they have supernovae in them, they can sometimes be bright enough to see with the naked eye. Similar-shaped galaxies that are thought to be far away, based on red shift, are dim, look small, and have supernovae that require large telescopes to detect. Now let us assume for the moment that this second group is actually nearby, but some deity-driven phenomenon just makes them appear distant: the stars in them are smaller, and explode more weakly, perhaps. Now, how does that assumption differ from this scenario: You set up an observatory on Interstate Highway 40 west of Amarillo, Texas, so that you can watch semitrailer trucks recede into the west. You have an unobstructed view of twelve miles of road. Your observations indicate that trucks that have just passed your observatory have bright taillights that are well-separated (in the apparent angular sense - you could measure the separation if you wanted too.) Other trucke appear to have dimmer taillights much closer together, and still others have very dim ones that can only be seen individually with binoculars. Now which is the more plausible explanation for these observations: A) Semis of approximately equal size are at various distances from you, and the laws of physics and optics govern how bright and far apart their taillights appear to you or B) the trucks are all nearby, but the ones that appear to be largest are the only full-sized ones. The second group are all Tonkas (with battery-operated taillights) and the third group Matchbox brand toy trucks. And with time, group #1 morphs into #2 and then #3. I prefer B. [ August 02, 2002: Message edited by: Coragyps ]</p>

08-02-2002, 12:28 PM	#5
MortalWombat Veteran Member Join Date: Apr 2001 Location: St Louis area Posts: 3,458	<a href="http://www.talkorigins.org/faqs/c-decay.html" target="_blank">The Decay of c-decay</a> <a href="http://www.infidels.org/library/modern/dave_matson/young-earth/additional_topics/supernova.html" target="_blank">The Distance to Supernova SN1987A and the Speed of Light</a>

08-02-2002, 01:35 PM	#7
Tom Sawyer Talk Freethought Staff Join Date: Jun 2002 Location: Toronto, eh Posts: 42,293	Thank you everybody. I've emailed him the links you've provided and he's going to look at them over the weekend and we're going to discuss it more on Monday. I'll keep you updated on how it goes. I've also got a few arguments of my own to use as well, I was just a bit stunned when he came up with the argument - I'd never met a Young Earth guy in the flesh before and it threw me for a loop. He's a vey intelligent guy and programs computers beside me and I didn't expect something like that out of someone like him.

08-02-2002, 01:38 PM	#8
Autonemesis Contributor Join Date: Feb 2002 Location: I've left FRDB for good, due to new WI&P policy Posts: 12,048	A trigonometric distance measurement to another galaxy sounds like you have misremembered something else you read. The proposed Square Kilometer Array is expected to be able to measure parallax distances to SiO masers in the nearby Magellanic clouds (~100,000ly). The SKA will be able to use intergalactic scintillation to achieve an angular resolution of .0001 arcseconds. To measure parallax to distances much farther than that will require an array with space-bourne elements. You're talking nanoarcseconds.

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