Creationists Questioning Speed of Light to Refute ‘Cosmos’

Creationists Questioning Speed of Light to Refute ‘Cosmos’

I jokingly said last week as as a
complete joke okay this was
just hypothetically completely kidding
when talking about Neil deGrasse Tyson’s
6500 lightyears
crab nebula example so no the grass
tyson on Cosmo is the new series on Fox
you know we kind of have proof that the
the universe is more than 6,000 years
because the crab nebula is 6500 light
years away
and we wouldn’t be able to see anything
that’s further away
if the universe were less than 6500
years old I jokingly said you know I
maybe conservatives are the religious
right will say
how do we really know the speed of light
I mean we could be deceived by God about
the speed of light I jokingly said it
and this has actually happened there’s a
group called Answers in Genesis their
is Answers in Genesis dot com and
they’re making this exact argument they
this is a quote what tyson of course
does an address in the program
is that young earth creationist
scientists do offer biblically
consistent models to explain
how we see faraway objects in space
without tampering with the laws of
one such model is the any so tropics
synchrony convention
which is based on the fact as Einstein
recognized remember mentioning Einstein
apparently gives you credibility
that it is impossible to objectively
measure the one-way speed of light
we instead measured the round-trip speed
have lied
and simply agree that the one way speed
must be happy above the total
read more about how this explanation
would answer the question of how light
from distant stars
could reach earth within the time
allowed in biblical history
in quote distant star light and for more
technically minded readers any so
tropics in Gurnee Convention
a solution to the distant star light
so what’s the problem with this theory
in layman’s terms the idea is OK
we’re assuming that light travels at the
same speed in one direction
that it does in the opposite direction
but we don’t really know that
we don’t know that it might be traveling
one way faster
and then we’re just dividing by 2 in
assuming it’s the same in both
directions the problem
is as is the case with almost every
single one of these types of arguments
the problem
is that it depends on non falsify a ball
claims made
mostly in this kinda hypothetical
philosophical sense there is no actual
evidence that would suggest light
travels at a different speed
in one direction then it does in the
other is hypothetically possible
that’s true but there is absolutely no
evidence for it
the idea was initially published in a
creationist Journal
called answers research journal in
September 2010
and it says without violating any known
laws of nature
we could have you special relativity
added as if they’re
is one-way infinite Lightspeed I
however I am there is absolutely
no evidence of this in both cases when
we look at the argument made in the
answers research journal
and the argument made by Answers in
Genesis you create
needlessly more complex calculations and
if we think that both
the simplest explanation is typically
the correct one
and that extraordinary claims require
extraordinary evidence as Carl Sagan
suggested there is a completely
ad hoc nature to this theory so
I was completely joking when I said next
thing you know
creationists will say well we might be
deceived we might not really know the
speed of light
I i think that the it is
absolutely astounding that this is now
being presented as an
actual beary and I’m not taking any
credit at all
for for predicting that this would
happen I was completely joking and it
turns out that


  1. If you want to go insane while your brain cells fry, just listen to a young earth creationist. Just remember that you will never get that time back. Or those brain cells.

  2. I am an electronic engineer majoring in microwave theory, Electromagnetic wave propagation is what I specialize in. The idea that light behave different in one direction than another is absurd and derived from the lack of knowledge about Maxwell's vector equations. I can practically say that every high speed full duplex radio linkup we have done over large distance that use a hop-frame has prove that it is absurd. But the theory behind it explains more than observations ever could.

    The speed of light can be defined from two perspectives, one is the quantum approach that causality is Planck length over Planck time, both are scalars and independent of direction as the physical properties of free-space, another way is by means of the properties of freespace through Maxwells equation where causality is a physical property of free-space dependent on the capacitance property (ability to hold an electron charge) and the inductive property (ability to store magnetic flux) of free-space known as permittivity and permeability of free-space. c=1/sqr(e0.uo) where e0=8.85E-12 and u0=pi.4E-7 The rate at which an electromagnetic wave propagate in any direction is dependent on the delay of electric charge and magnetic field experience due to the permittivity and permeability causing space to behave as a 377Ohm transmission line in all directions. The impedance of freespace is also dependant on permittivity and permeability of free space as Zo=sqr(u0/e0) both scalars and independent of direction

    As long as free-space has the physical properties of permittivity and permeability or as long as Planck length and Planck time remain constant, causality will be at constant in all directions. meaning that Vp (phase velocity) of light in free-space will remain constant for all directions. As a side note, free space is not nothing, it has physical properties. c is not the speed of light, it is the rate of causality, the rate at which energy can propagate in free space. The speed of light is Vp, (phase velocity) where vp=c/sqr(er) this means that light can go slower than c but not faster depending on the permittivity of the medium, when the medium is free-space then vp=c. then causality and phase velocity of light is the same. What I try to say is, we know enough about electromagnetic propagation such as light to know that its rate of propagation is independent of direction as none of its properties which its depends on are vectors. No credible scholar will take this man seriously.

    I do believe it is possible for permittivity and permeability of free space to deviate over position and time in the universe due to distortions in the fabric of spacetime, while there is no scientific proof at this stage, it may affect what we see as a red shift in what we assume is an expanding universe or the way we understand the phase velocity of light in higher optically dense mediums. A deviation in such physical properties can cause the speed of causality to change in an objective perspective while this is less likely to happen in a relativistic perspective where c is a relationship between the absolute observer and the absolute causality. meaning, what change for light will change proportionally for you, so your observation remains constant. The causality is said to be constant because the properties of freespace is assumed to be constant. But as I say we do not have any evidence yet and it would be very hard to find it in anyway. At this stage we need to assume it remains fairly constant in terms of relativity. But even if it is the case, the total flight time of light would be the same in both directions, but if there is deviation for the observer in a cosmological term we talk about billions of light years for any measurable effect. The reason it would be the same in both directions is simple, the sum of 1,2,3,4,5 is the same as the sum of 5,4,3,2,1, as long as the path is the same, the time would be the same regardless of direction as causality is dependent on scalars and not vectors.

    The scientist which this movie refers to, answersingenesis seems to assume that the speed of light is based on cosmological observation which is subjected to error, but its not how the speed of light is determined. David suggest that it unlikely but hypothetically possible, but I may add that it is not even hypothetically possible because the hypothetical analysis of this subject is called quantum physics and quantum physics hypothesize that its Planck length over Planck time, both scalars independent of direction, therefore it is a hypothetical impossibility for light to have two different speeds for the same path.
    I believe the current universe is about 13.8billion years old and the physics behind that is fairly solid, while I believe there is a reasonable case to be made to speculate around Hubbles law about the observable universe as it includes plenty of assumptions as it relates to dark energy.

    As a conservative who do not always agree with David on social matters, I must give him 10/10 for calling this absurd nonsense out. answersingenesis must do what other creationists do, dont ask to many questions, dont try to invoke science into religion, it does not work.

  3. It is proposed that the universe began at a point and expanded billions of times it's size instantly exceeding the speed of light covering galactic distances instantly. No one talks about the relativiatic aspects of this hyperinflation. Creationist would be well served to explore hyperinflation as superluminal elements experience negative time.  If creationists are smart enough they can develop a reasonable argument for their beliefs, but they are not so they will never see science can prove their faith.

  4. EVEN IF…. Light could travel instantly in one direction, then at most it could only be doubled in the opposite direction….
    That still means that in a 6500 year old Universe, we could only see, at best, 13,000 light years.
    THAT isn't even halfway to the centre of our own galaxy – yet if you look at the Andromeda constellation, without even needing a telescope or binoculars – you can see clear out of our galaxy, all the way across to another separate galaxy (2 MILLION or so light years BTW)

  5. Assholes in Genesis are a bunch of LYING religitards whose assertions are not worth pissing on, let alone considering.

  6. you said you measure the round trip speed of light and half that. But what if light has a cuppa when it gets there before travelling back? Have you thought of that? Checkmate athiests!!

  7. I'm actually not sure that physics allows for a variable speed of light. That's because of the famous energy-mass equivalence. The mass of a given amount of energy is a function of that energy and the speed of light in vacuum (c). If c were variable, that would mean that the mass of a given amount of energy would also be variable, which I think would break all kinds of conservation laws.

    Also, what creationists do not understand is that if the speed that light travels changed, it would affect its wavelength. If light emitted by a star started at, let's say, 1000*c, and then it slowed down to c before it reaches us, the wavelength of that light would change 1000-fold. It would not be in the visible light spectrum anymore; it would be off by three orders of magnitude.

    And that's just a couple of problems with the idea.

  8. Actually it's not hypothetically possible that light changes its speed… because we know that the speed of light is a constant, relative to the space it is traveling in.

    I really don't feel like typing a dissertation on it to explain it, but this is why in the formula…
    light is represented by …c… meaning constant.

    Look it up, read it, self educate.

  9. What these funditards seem to misunderstand that you can't just rewrite the laws of physics without having to then rewrite all of them.

    If, as some suggest, light was faster in the past than it is today then radioactive elements would also be more radioactive and their half-lives would be shorter. This means that the Earth would never have properly cooled as it's, in part, the radiation from all those heavy elements at the Earth's core that is keeping the core molten. If the half-lives were shorter it would mean more heat. More heat means less solid crust. Less solid crust means of course that the game "the floor is lava" you used to play as a child would be real.

    Every single time AIG or some other fundie group tries something like this it never works when you have to put in into the framework of actual science.

  10. The Catholic church did that already centuries ago, trying to calculate rules for the retrogradic movement of the planets. It worked out somehow. Until someone got the idea to put the sun in the center and all got very easy = reasonable after that.

    The Catholic church overcame that fallacy and readily accepts the (correct) concept.

    But modern American elucidated Christians know better and fall back into the good old times of the middle ages.

  11. The presenter does a fine job, but does not understand the argument. Creationists depend on speed of light being a vector quantity i.e. depends on direction, motion of source or observer– obeys galieleian transformation. However, Maxwells equations predict light is a scalar quantity, i.e. independent of those things. Michealson-Morley confirms Maxwell, light is not a vector quantity.
    Einstien took this notion and presented a consisted framework of gravity, such that the speed of light is independent of direction.
    No one just assumes that light speed is the same in all directions, this is a cornerstone of physics and confirmed via countless experiment

  12. Couldn't we test for this? Just put two stations up both with a laser and sensor shooting their beams at each other and see if there is a measurable difference between light traveling north or south, east or west, left or right, up or down or so?

  13. A slight correction is needed here. Just because a person can create a hypothesis doesn't mean that the hypothesis is possible.

  14. Creationists have been making all sorts of claims about the speed of light for decades now. You're not even discussing the one they claim the most, that the speed of light varies greatly depending on what it goes through. Oh, and of course creationists need no actual evidence or true science to make these claims.

  15. Young Earth Creation Scientists are FUCKING MORONS! Normally I temper my atheist views but when these YECS fuckwits chime up, my blood boils and I go HARD-LINE VEHEMENT ATHEIST!

  16. The problem here, as with every literal creationist idiocy, is that they take a bronze-age myth and seek to claim it as literally true – that, for some inexplicable reason, is their 1st principle. In order to do that, they have to leap through vast metaphysical hoops, LIE wholesale about science, and utterly deny objective reality.
    I'd have the same problem trying to prove that, eg, the Greek myths are literally true: it simply cannot be done.
    Sure, if you were born in this religious bubble, or even if you converted to it, you are going to have a problem dealing with the weight of evidence against the nonsense, but sooner or later the cognitive dissonance is going to hit you… and you'll either come out of the bubble, or jam your fingers in your ears and your head up your arse.

  17. Actually their is some evidence that the speed of light was different in the early universe. Physicists analyzed the light from quasars 13 billion light years away as it passed though clouds of molecular gas and found that the spectroscopy differed from the same light passing though gas clouds closer to the observation point. If the speed of light has been increasing steadily for the last 13 billion years, it would give the appearance of an expanding universe. Andy Albrecht Joao Magueijo, and Prof. John Webb using high resolution spectroscopy of quasars.

  18. The majority of the religious will jump through all kinds of convoluted hoops to hold onto the insanity of their own beliefs… nothing surprises me anymore.

  19. It always used to bother me when my friends would call them all "Creatards" but after hearing this answer the description seems apt :/ sawwy…

  20. Why atheists fail to understand omnipotence is beyond me.

    Refuting a creator by claiming he has to be bound to the scientific limits of man is completely illogical. Assuming the creation story of the Bible is true, then God created the stars and their light simultaneously, obviously. The alternative is the entire universe expanded on the fourth day, which would mean the light was also moving at superluminal speeds, but the idea that God created the universe and the light makes more sense, since the Earth would have had to have been shielded from the effects of the expansion to preserve the plants already created, and since light was created before the stars.

    We've come far enough to realize all forms of matter (fermions, leptons, and bosons so far) are simply disturbances/vibrations in a series of energy fields. That means God could simply create a universe of energy fields a certain size, then shift everything into its forms of matter, and apply the various momentum associated with gravity. It's even easier to explain, if the universe is seen as having four to eleven spatial dimensions. There are a million hypothetical ways it could have been done, but atheists seem to think that God could only do it one way, and that disproves various things. It's like saying the only way Jesus could have healed someone was through modern medicine, which is equally absurd.

  21. Answers in Genesis. The "brains trust" behind the creation museum and the "technically perfect replication of Noah's ark" (with buildings behind it holding it up – and dinosaurs inside. "Vegetarian T-Rex"!). If anyone believes a word these creeps say, they're dumber than those making them up.

  22. Because things travel at different speeds in different directions with nothing stopping them or changing their speed.

    Obviously, this is not true. Lel.

  23. same view different subjects if randy johnson throws a ball against a wall of whatever matter he throws at 100 mph the reflection of that ball will travel with way less velocity than half the speed back in his direction example you can have a 200 watt bulb if you turn it on in a room of pure white you will be blinded but if you do the same thing in a room of black your fine in olden times how long did it take a wicken lamps light to reach the stars or a candle for that matter humans can produce such feits prove me wrong i hope someone reads this and prove me wrong sorry about the punctuation and spelling errors

  24. We do know the speed of light because it is an integral part of the GPS positioning system. The known value for the speed of light is used to calculate the distance between the satelite and the receiver without two-way communication.

  25. If the speed of light is vastly different depending on direction, couldn't it also be that scientists underestimate the age of the cosmos? I mean that creationists wants to think that we are on the receiving end of the "fast light" so everything seems older than it is, but what if we are instead on the receiving end of the "slow light"? Creationists have opened yet another vector of attack for us rational folks. Thanks, creationists! 🙂

  26. Well I think the simplest explanation for why they are wrong is that there is mathematical proof for the speed of light being the same in all inertial frames of reference. For example, if I am moving at 10 miles per hour and you are stationary, we both see light move away from us at the same speed. There is no "perspective" that would change the speed of light and we know this from basic E+M. When you take the equations for E+M and put them in empty space, you find that an E+M wave (light) travels at a speed of c (the speed of light) WITHOUT respect to something else, which was baffling to physicists at the time, but it is true.

  27. If the speed of light is finite in one direction, and infinite in the opposite direction, a laser can not work. To function, a resonant cavity must be established, which keeps the light oscillating in either direction through the amplification medium
    That the speed of light is infinite in one of the two senses means that light can not resonate, or reflected in the mirror in that direction, as we are.
    That means that the laser does not work
    As we can see that lasers work, even that they change their mode of resonance in a predictable way when the distance between the reflectors is modified, the light can not have different speeds depending on the direction of movement

  28. Creationist claims about evolution to witch they know nothing about is an equivalent to donald trump's fake news

  29. The Bible is not inerrant, and there is no "6000 years" clause anywhere that I have seen. Also, the English Bible cannot be heavily relied on because of translation errors, so if there is such a clause then we can't trust it. I have seen die hard conspiracy theory type Christians acknowledge the fact that the universe is not 6000 years old, and that their Bible is flawed. Steve Quale provided such a reinterpretation in his book that fits with the scientific model.

  30. Kinda surprised David mispronounced anisotropic like "a-niece-o-tropic" when it's actually said like "an-ice-o-tropic/trohpic", he's usually spot-on with stuff like that.

  31. That Einstein proposition wasn't correct. We can measure the ONE way speed in various manners.
    We measure the sun's speed (of light) TO the Earth by occultations/transits with Mercury, Venus.. and with other planets for their distances too.
    In labs, we often do one-way tests.
    Two way tests are simply EASIER, because we can make the observation and calculations from the same point as the emissions.

  32. I have no problem in believing that there is more to existence than we imagine, but with that said organised religion will never help us understand more. I have no problem with the Eternal Return, but organised religions are human made organisations that have no interest in the Search for Truth & Understanding. If there is a Divinity, it will not be found via human organised religion.

  33. What if you used two surface-silvered mirrors, and took readings with those mirrors placed at various positions yet retaining the same overall distance?

  34. The speed of light is constant. If it wasn't the universe we lived in would be completely different. The speed of light is the speed of light. Return trip? WTF?! What are they kids?

  35. I worked out as a 10 year-old that the Andromeda galaxy was 2 million light years away thus the universe is at least 2 million years old.

  36. I love the irony of creationists using GPS to get to the ark museum. Why don't say that the GPS is lying or fake? The believe when it's convenient or profitable.

  37. They just don't understand how anything works. Things wouldn't have mass or everything would turn into black holes if you change or get rid of the speed of light. We don't see that.

  38. Gawd just put dem galuxcees der to challunge my faith! I still believe in you Gawd of the gaps – I mean the Bible

  39. GPS is one way and we can defnitly measure that speed. Likewise,the uplink speed is identical as well. So, every cell phone, ipod, uber driver blows this stupid creationist theory out of the water every moment of every day

  40. "Creationist scientists". I haven't wanted to laugh and cry at the same time while going on a bitch-slap spree this hard before

  41. Light does not travel, it is exposed. Darkness is a curtain. Life is about choice. Keep it closed or open it. Nothing more.

  42. You know there are many evolutionists who don't even know that light has a fixed speed… It's really not an issue with a belief system, it's just that not everyone is a scientist!

  43. I sincerely dont mean any offense and i like this guy's channel, but he looks like the love child of Jake Gyllenhaal and Joseph Gordon Levitt. I dont think thats a bad thing, just wanted to share my thoughts….

  44. i'm not kidding here, these people who live for evidence are like robots REALLY!. they are not fully human. as is well illustrated in sheldon cooper . ok where is the evidence light remains constant and uncorupted traveling over trillions of miles . oh sorry I dont mean to make you think cos I know you prefer just repeating the crap in your text book, you half formed drones .

  45. If the speed of light was different in different directions, all of the calculations of special relativity would be incorrect, because they depend on the speed of light being constant. Light bending by gravity would be different from what we measured if light was infinitely fast. No black holes would exist if light could exit them in one direction due to infinite speed. GPS simply would not work if relativity would be wrong, because the GPS system uses relativity time-correction algorythms. The timing between flash and thunder would be direction related for an observer. We do not observe any of this. Has anyone of Answers in Genesis thought about those simple things before proposing complicated models with divine mathematical intervention? And which direction should be the direction "to infinity"? From "there" to "us"? Cannot be, because we measured the speed of light by looking at Jupiter's moons, too. Or do they think "infinite" is from left to right, while "slow" is from right to left? In this case we would see billions of light years into one direction but only 6000 light years into the other direction. This proposal simply does not work.

  46. Yes the there is no evidence for different speeds of light and also relativity based on the assumption that the speed is the same both ways, makes accurate predictions, it is very consistent, it was confirmed by numerous tests for more than 100 years and still holds.

  47. What is "God speed"? Faster/slower than light? Can Godspeed be measured? I tried to explain to a creationist that exploding objects move away from its source. Galaxies continually moving further apart. There is the evidence of a big bang. If simply created, there'd no need for galaxies moving further apart. Hell, no need for anything outside our solar system if no other life in the universe and if all this was created.

  48. The big breakthrough in measuring very long distances was the exploding star which is a given "candle" for the effect we can measure and the other fact that if this exploded anywhere near us, we would all be dead. All these horses bolted a while back and refined by todays technology. It leave God with very little wiggle room left. The only big ones left to answer are the something from nothing that laymans find funny which is really the fault of the same smart people telling them nothing in your hand is nothing! so dont be stupid. Now we tell them nothing isnt nothing haha and try to explain this complex situation is the basis for all matter and energy/time popping into existence.
    When you attack religion for so long with more and more facts, they are going to fight back and now we have involved them in complex math and nothing of course their brains cant handle this extremely complex maths and theoretical area that only the smartest people on the planet are trying to wrestle with.
    Like all problems in the past, this may be solved as well which sadly will leave all the old fairy stories gone forever.
    What happens on other planets that have evolved life? Is it the same where they go through their god time early on and carry it forward? OR is that a unique failing of nature and evolution on Earth and humans do believe but interesting other animals dumber than us do not! ? Are we so smart and what would aliens races think of us and our beliefs?

  49. The bible is not a science book. Seven d says does not mean a 24 hr day. It is a time period that we don't know but used as a measure of time. God wants us to be able to understand things. Our time sense is much different than his, a thousand years is like a day to him. So we don't how long a period of time or how long they lasted. He is just giving a reference for our tiny minds. Yes any logical thinking person knows the universe is older than 6000 years. The time of mans history is only about 6000 years old. I believe in creation but creationist are doing a disservice here. People are always trying to make the facts fit there ideas. The facts are the facts. The earth is very old. The earth was placed in the most perfect spot was it not. Not to close and not to far with and atmosphere to keep falling space debris from hitting us. I don't understand how someone cannot believe in God. The evidence is his work it is ever where.
    All the horror on this earth is mad made.

  50. Some knowledge that God did give. People knew mostly nothing abo it the. Bury your pop, guardian the sick. Do not eat pork. Pork carried a worm or something, and if not cooked at proper temp will make you sick. Moos said the death was a sphere hanging upon nonthing

  51. Because of mans philosophical imaginations you spout and tout the exact same "Hypothetical & Philosophical Sense" lol. The IS NO actual "Evidence That Would Suggest" light travels at the same speed in one direction than it does in another, "It's Hypothetically Possible, That's True. BUT There Is Absolutely NO Evidence For It…" The idea was initially taken up in an atheistic 'Convention'..

    It's a LONG and well known "FACT" in Physics that ONLY the 2-way speed of light can be measured.

    Do some "Basic" research of the proposal 1st before you and others, such as your 'Pictured Guess' state to the contrary of this "LONG KNOWN SCIENTIFIC FACT".

    To continue to spout "Pseudo Science" you only establish your and others "Cognitive Dissonance" in regards to this "Scientific Fact"…

    Just look up the meaning of Cognitive Dissonance and please do try and explain how you and most are not just this definition…

    Just because most of the worlds populous is ignorant of 'This Scientific Fact' by NO MEANS proves it to be wrong…

    ANY experiment one wishes to even try and detect the "One-way speed of light" results in a return light signal required to synchronize clocks. So it's truely impossible to truly have a one-way speed-of-light measurement.

    From Wikipedia, the free encyclopedia

    Jump to navigation Jump to search

    When using the term 'the speed of light' it is sometimes necessary to make the distinction between its one-way speed and its two-way speed. The "one-way" speed of light, from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector. What can however be experimentally measured is the round-trip speed (or "two-way" speed of light) from the source to the detector and back again. Albert Einstein chose a synchronization convention (see Einstein synchronization) that made the one-way speed equal to the two-way speed. The constancy of the one-way speed in any given inertial frame is the basis of his special theory of relativity, although all experimentally verifiable predictions of this theory do not depend on that convention.[1][2]

    Experiments that attempted to directly probe the one-way speed of light independent of synchronization have been proposed, but none has succeeded in doing so.[3] Those experiments directly establish that synchronization with slow clock-transport is equivalent to Einstein synchronization, which is an important feature of special relativity. Though those experiments don't directly establish the isotropy of the one-way speed of light, because it was shown that slow clock-transport, the laws of motion, and the way inertial reference frames are defined, already involve the assumption of isotropic one-way speeds and thus are conventional as well.[4] In general, it was shown that these experiments are consistent with anisotropic one-way light speed as long as the two-way light speed is isotropic.[1][5]

    The 'speed of light' in this article refers to the speed of all electromagnetic radiation in vacuum.Emerging Technology from the arXiv

    A View from Emerging Technology from the arXiv

    The One-Way Speed of Light Conundrum

    There’s no dispute over the constancy of the speed of light when measured over a round trip. But what of its speed over a one-way trip?

    November 9, 2010

    If you had to pick one idea that is emblematic of 20th century physics, a good candidate would be the universal constancy of the speed of light. When Einstein put forward this notion in the special theory of relativity, it solved the long-standing mystery of why measurements did not show any variation in the speed of light with Earth’s motion through space.

    It also ushered in the idea of space-time as a single entity. This leads directly to the derivation of the laws of physics as spacetime symmetries, a process that has been crucial for both general relativity and the standard model of particle physics.

    So to question the constancy of ‘c’ is to invite controversy. And yet there are reasons to think we should certainly investigate this hypothesis in more detail using the tools of experimental physics, say Farid Ahmed and pals at York University in Toronto Canada. Today, they give us an interesting review of the various ways in which the measurements have been made.

    The experiments to measure the constancy of the speed of light fall in to two categories, say Ahmed and co. In the first are experiments like the famous Michelson Morely interferometer which measure the round trip speed of light along some closed loop. This is essentially its average speed over some distance and back again.

    No variation has ever been found but these experiments leave open the possibility that the speed of light is different over each leg of the journey. So there is another category of experiments which attempt to measure the one-way speed of light.

    One interesting question immediately arises: how do you measure the one way speed of light? It turns out there are various methods. One idea involves the emission and absorption of gamma rays by certain kinds of atoms in a solid. The process of absorption is very sensitive to the energy of the gamma rays. So if the speed of light (and therefore its energy) varies with direction, then the rate of absorption ought to change too.

    In the 1960s and 70s, various physicists looked for a directional dependence by placing a gamma ray emitter at the edge of a rotating disc and an absorber at the centre. They then looked for any difference in the rate of absorption as the disc rotates but found none.

    Neither have physicists using other techniques found any variation either. (The controversial Bulgarian Stefan Marinov claimed to have found evidence of a variation in the one way speed of light but his claims are not considered valid by most mainstream physicists.)

    Ahmed and co say these experiments need to be refined and improved and are working on their own measurement of the one way speed of light.

    The work may have important consequences. Ahmed and co point out that string theory predicts a violation of the constancy of the speed of light as does another idea which proposes that a variable speed of light would solve various problems in cosmology.

  52. From Wikipedia: The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is 299,792,458 metres per second (approximately 300,000 km/s (186,000 mi/s)[Note 3]). It is exact because by international agreement a metre is defined to be the length of the path travelled by light in vacuum during a time interval of 1/299792458 second.[Note 4][3] According to special relativity, c is the maximum speed at which all conventional matter and hence all known forms of information in the universe can travel. Though this speed is most commonly associated with light, it is in fact the speed at which all massless particles and changes of the associated fields travel in vacuum (including electromagnetic radiation and gravitational waves). Such particles and waves travel at c regardless of the motion of the source or the inertial reference frame of the observer. In the special and general theories of relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc2.[4]

  53. I think that reviewing the voyager missions would be an interesting way of measuring time and speed. Much slower then the speed of light yet impressive speed and yet it took years and even decades to move thru just our own solar system which is just a fraction off the distance to the nearest star. Creationist are just unwilling to accept the wealth of known information on regard to the vastness of space. Anyone who believes Dinasours walked beside man is just unwilling to accept the reality of life. The children of these misguided people are at such a disadvantage in the real world.

  54. comments on current thought about the speed of light change.
    Re incredible claims need incredible evidence, the claim that at 0.00000000000000000000000000000000001s after the big bang the universe expanded trillions of times is a pretty incredible claim lacking even credible evidence.

  55. Actually – according to Einsteins Theory of Relativity – the speed of light is constant in every direction for every observer – so Ken Spam is totally wrong on that. That is how Einstein produced his theory that the speed of light is constant – and the other components – space and time revolve around the speed of light. If the speed of light were constant – we would get different values for speed through space and time.

  56. Good old leftist Packman. The earth is young, bro. Have me on and I'll demonstrate that and I'm uneducated compared to you I'm sure.
    I'll hold up the young earth side. Or are you scared?

  57. You didnt predict anything. That is not saying the speed of light changed or that it's a deception.
    Its acknowledging the light time and proposing a different convention.

  58. Lol you forgot to tell your subscribers that the Big Bang cosmology also has a light travel time problem called the horizon problem. Secular astronomers have even proposed some variable speed of light theories to solve it. It’s pretty disingenuous to criticize a theory for a problem when the theory you stand on has an equivalent problem.

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