Falsifying a young Universe. (re: Supernova 1987A)

A light year is a measure of distance. It assumes the speed of light is 299,792,458 m/s, and it is the distance light travels at this speed in a year. Even if it turns out that the speed of light was different in the past, the length of the light year would not change because it is based on the speed of light as measured in modern times.You are correct, though, that the equality of light years with the time that has passed since the light left a distant object like a star would no longer hold if light has not always traveled at the speed measured today.There is no evidence that light has ever traveled at a speed different from that measured today.--Percy

The apparent reduction in the speed of light in physical media such as glass and water is because the light is absorbed and retransmitted. This process takes place at different rates for different frequencies (and therefore different energies) of light, which also explains why different frequencies of light appear to have different speeds within the media. When traveling from its transmission by one atom to its reception by another, light always travels at the speed of light. Another way to think about the speed of light is that its the speed at which the effects of physical phenomena are transmitted throughout space.One thought experiment makes this last fact especially apparent. Imagine you wanted instantaneous communications with the moon, instead of having to wait 1.3 seconds for radio communications. You construct a rigid steel rod from the earth to the moon. When you push your end of the rod on earth, the other end of the rod on the moon moves instaneously. Voila! Instant communication! Except that it's not. It takes the fact that the end of the rod on earth has been pushed 1.3 seconds to reach the moon. And probably longer, because our rigid rod isn't actually perfectly rigid.--Percy

You were also offered much other evidence, for example, of the speed of light being measured to be the same at great distances from us, for example, Message 56 by Loudmouth.It is difficult to think of a helpful response to "Big deal." Can you put into words why you think inconclusive the evidence showing that the speed of light, decay rates, and other physical constants, are the same everywhere and in every era that we look in the universe?--Percy

I think you must be missing something, because the supporting data is pretty abundant and complete. Could you be specific about what you think is being conjectured?--Percy

Instead of addressing each specific question, let me address just the gist of what you're asking, which seems to be, "How do we know we're right?"The answer is that we don't know we're right. That's why theories are considered tentative and changeable rather than fixed and permanent.It is not a valid rebuttal to say, "You could be wrong." We readily agree, as you would have to agree that *you* could be wrong. Such arguments weigh just as heavily on both sides of the debate and so cannot move either side's position forward.But our position is supported by a wealth of evidence, and so a valid rebuttal of our position can only occur when you have counter-evidence or counter-arguments that undercut our position.--Percy

If that is what we'd said, then I'd agree with you. But we didn't simply declare that decay rates and the speed of light were the same in the past. We've actually measured them in the past. This has already been described for you in fair detail, so more briefly this time, when we observe a distance star or galaxy, the light arriving here left a long time ago. We are actually seeing the star or galaxy as it existed long ago. We analyze the radio emissions from these objects to determine things like speed of light and decay rates. And we find they were the same long ago and far away as there are here and now.We have never observed any physical constant to be different anywhere or anytime in the universe. The evidence gathered to this point indicates the constancy of physical constants throughout time and space. While it is possible there are exceptions hiding out there, one doesn't rebut evidence in the hand simply by raising the possibility that there might be exceptions in the bush somewhere out there. Science already takes this possibility into account by declaring that all theories are tentative.--Percy

You're giving the appearance of not having read what you not only responded to, but actually quoted. You ask "Based on what?" right after I've explained that "We analyze the radio emissions from these objects to determine things like speed of light and decay rates." We even made direct measurements of the speed of light at remote distances, such as Loudmouth described in Message 56.There's nothing that obligates you to accept the evidence supporting these conclusions. You can continue to say "Big deal" and ask "Based on what" with no ill effects. But this approach is simple denial, and if you're interested in a discussion then you'll explain what it is about these measurements and analyses that leads you to reject them.The other issue you haven't addressed is positive evidence for your point of view. As far as I know, there is no evidence that the speed of light has ever varied. This places you in the somewhat awkward position of rejecting a position with evidence while accepting a position with no evidence. You seem to have no better argument than "You could be wrong," which we freely admit, but it is scant comfort for you since it is just true of yourself.--Percy

Then I suggest you get into it. Tell us what factors are being missed. If we're missing certain factors, aren't we missing them for Supernova 1987A? Aren't these factors therefore relevant to this thread? Please, tell us, what factors are being missed?--Percy

I sure hope you guys mean neutron stars. Neutrinos are elusive particles that do not interact much with matter.--Percy

The question was about how faster speeds of light are consistent with the evidence we have. You relied, "Less time involved." You are correct that traveling the same distance over a lesser time yields a higher speed. No one disputes this. What you lack is evidence.Please understand that it isn't that you are wrong. Take as an example a theory that says all crows are black. Let's say you find every crow you can, and every single one is black. After you've examined many, many crows you can have great confidence in the theory of black crows. Someone could say to you, "Sure, you've seen lots of black crows, but there could still be white crows out there." And you would have to concede that he is correct. But the possibility that you could be wrong is not the same thing as being wrong. Until a white crow turns up, the theory of black crows is still a solid theory.In the same way, observational and theoretical evidence for the speed of light being a constant is unequivocal and unambiguous at this time. That doesn't mean that evidence or theory might not turn up that the speed of light is not a constant, but it hasn't as of yet. And so this is a very solid theory, because the possibility of contrary evidence, which is true of all theories, is not the same as actual contrary evidence. You can remind us all you like that someday we may find light traveling at different speeds than c, but until you actually find evidence it is a possibility not seriously considered, especially for the dramatic differences in c required for a young universe.--Percy Small grammatical improvement. --PercyThis message has been edited by Percy, 01-21-2005 16:36 AM

I think the Google hits you found for "neutrino stars" may not be referring to actual stars composed of neutrinos, which wouldn't be expected, but are stars which have gone through a stage that produces many neutrinos. There wasn't much explanatory out there, but I did find this at http://www.phys.hawaii.edu/~jgl/nuosc_story.html: But maybe there's more to it than that. Anyone know?--Percy

I believe Cosmo is saying he doesn't want to discuss it anymore, but that he's not conceding because he believes those who know more than him, such as Russell Humprheys (author of Starlight and Time), would be able to provide the necessary evidence and arguments.--Percy

I don't think Einstein ever said this. It seems unlikely given that Einstein introduced the concept of spacetime, itself raising questions about simultaneity. I can't find it in Bartlett's or The Expanded Quotable Einstein. Did Albert Einstein say the only reason for time is so that everything doesn't happen at once? mentions a possible source.--Percy

If I could quibble a bit with your wording: It's just about the word "accepting." We have hard evidence for how far away stars are, with the error ranges growing with increasing distance. There's also something called the cosmic distance ladder. It starts with the distances to close stars established through the parallax of Earth's orbit (e.g., Alpha Centauri) as a basis for establishing the distance to more distant stars, and moves outward from there using a variety of techniques.I'd have the same quibble with the word "accepting" in the other half of your sentence: I think we have pretty solid evidence that software runs on computers. Unless he's in some facet of the computer industry, my guess is that Starman accepts that software runs on his computer because that's what everyone else thinks, not because he has any personal experience with the details behind writing/compiling/loading software.Starman wasn't investing any time understanding people's posts. There was no discussion. He was mostly just tossing off one and two sentence content-free responses.--Percy

Yeah, that sums it up pretty well. That's a good approach with some people. You know you're not going to convince them, or even get them to engage, but it sure is fun lining up all the ducks of an argument for the benefit of others.--Percy