JungleDjinn, I do agree with you about the string conjecture. It completely muddies the water by calling it a 'theory'.

JungleDjinn wrote:So it strikes me that the substantive argument here is whether the notion of the ET Hypothesis has been aptly named. Would it make a difference if it was called the ET Conjecture or the ET Proposition, and would the preceding nine pages of posts and arguments have occurred if it had been differently labelled? And just to throw a cat into the pigeons, I'm henceforth going to refer to String Theory as the String Conjecture until someone can demonstrate its testability.

So far I've liked this site, but at my welcome page I was warned that this site is a sometimes dysfunctional little family. That seems to arise from personal attacks and ridicule between discussants. I don't agree with everything Landrew posts, but I agree even less with the ridicule that's aimed at him.

I don't think I've ridiculed him. The thing is that he's been insisting that people 'make proper use of the scientific method' when considering the idea of ET interaction with humanity. And the problem is that he won't even formulate a hypothesis. All he's prepared to say is that 'aliens may have visited Earth (and interacted with us)'. As Hack pointed out earlier, that's not a hypothesis at all, let alone a scientific one, so insisting that people 'properly' use the scientific method in considering it doesn't make sense.

Saying "aliens may have visited Earth and interacted with us" is exactly the same as saying that "it is possible that aliens have visited Earth and interacted with us". Is it possible? Well, yes. Anything's possible. It's possible that there were fairies in Elsie Wright's and and Frances Griffith's backyard, and their evidence was of better quality than anything I've seen presented by Landrew so far:



So yes, I'm prepared to accept that it's possible (though rather remotely). That said, until I see any decent evidence that it's actually true (or even likely), I'm not particularly interested. I have better things to do.

stijndeloose wrote:The thing is that he's been insisting that people 'make proper use of the scientific method' when considering the idea of ET interaction with humanity. And the problem is that he won't even formulate a hypothesis. All he's prepared to say is that 'aliens may have visited Earth (and interacted with us)'. As Hack pointed out earlier, that's not a hypothesis at all, let alone a scientific one, so insisting that people 'properly' use the scientific method in considering it doesn't make sense.

I'd say possibly the major thing regarding the tone of responses is that here (as apparently elsewhere) landrew seems to have a thing about accusing skeptics of failing to be properly skeptical or open-minded (ie failing to be as good as he thinks he is) without giving much in the way of appropriate evidence for the accusations even when repeatedly asked.

Threads that start off with arrogant claims of someone's own superiority, even if those claims are incompetently attempted to be hidden under claims of other people's inadequacy, seem likely to attract a certain style of reply, albeit quite likely a hoped-for style of reply.

As for this thread, it started off by landrew making objectively inaccurate comments on a criticism of a review, and seeming to miss the entire point of the criticism - that a book supposedly presenting evidence appeared to have not even considered or presented much information which appeared to undermine some of the evidence.

Before anyone had even replied, landrew then went on to say

"The claim that the subject has been "completely debunked" is completely groundless."

clearly implying that the piece he was being critical of had made the claim that the subject had been completely debunked when it had simply not said that

landrew then repeatedly failed to address that misleading claim when it was repeatedly raised by other people.

I don't think someone whose posts object to someone being criticised for presenting a one-sided picture, whose style seems to be, at best, overexaggeration, and who apparently considers it better to ignore past falsehoods that they have written rather than admit to them is in a position to lecture anyone anywhere on 'the scientific method', let alone anyone here.

JungleDjinn wrote: In science, a theory is a hypothesis that's been validated, or perhaps I should say is a testable hypothesis that's not been falsified enough times that it becomes honoured with the promotion to a full scale "theory"

Not quite. A theory is an integrated explanatory framework dealing with all the hypotheses, observations and laws pertaining to a specific area of interest. Hypotheses don't get upgraded to theories, they're qualitatively different things.

(I'm skeptical of this process also, cf untestable String Theory (sic)

Well, there are certain postulates arising from M-Theory that are in principle testable and therefore falsifiable. Whether or not we have the means to test them now is a different matter, but they are testable. The existence of extra dimensions, for example, is testable, and I detailed in a previous post how that test might work. You'll find the relevant post here. Further, there is a cosmological model arising from M-Theory that is also in principle testable, namely the Turok/Steinhardt 'brane-worlds' model. Calilasseia has presented the papers in some detail here. As always, to ensure that I'm not misunderstood, I'm neither a supporter nor a detractor, preferring to wait until the evidence is in. To say that it isn't a theory, or that it is untestable and unfalsifiable, though, is simply wrong.

Personally I have no idea whether there are aliens out there or not, but Fermi's Paradox is a truly scary one to contemplate in all its complexity.

There's nothing complex about the Fermi paradox and, in fact, it isn't actually a paradox. It's also beautifully debunked by the Drake Equation, which I present in detail in the Equations Thread here

It strikes me that both ends of the proposition that there is alien life out there and there isn't alien life out there are equally unlikely when we look at the evidence, or the lack of it. It messes with my mind, if there is life out there, why haven't we found any evidence of it within the information we get from across the universe dating almost back to its event horizon of 13.7 billion years?

See the above linked post. This is really straightforward to deal with. The big problem here is our inability to grasp the scale of the cosmos. Again, this is dealt with in the linked post from the Equations Thread.

If there is no life out there, WTF is that all about? Could we be the only ones in this enormous setup - how likely is that?

Certainly we could, but I deem it highly improbable. The simple fact, though, is that we don't properly understand all the variables, such as how many routes there might be to chemical abiogenesis and what sort of time-scales might be involved.

Problem is we have no means of knowing whether we are in a typical or non-typical situation

Or even if terms like 'typical' can be robustly applied to the universe at large. It's an extremely variable place, in some senses, although extremely invariant in others.

as ours is still the only planet in the universe about which we have certainty of the existence of life (if only we had a bit more respect for it, but that's yet another rant), and we have no other examples of life on planets that would enable some basis of comparison.

Precisely. Any probability calculation we can currently conduct is going to be loaded with unknown variables, as the Drake Equation demonstrates beautifully.

Perhaps there is lots of life but it tends to be planet bound or system-bound and there are none close enough to have EM technology we can detect.

And that right there is the big one. Thing is, life could be abundant even in our own neighbourhood and we might never know it. The unknown variables just involved in life are huge, and the situation is only exacerbated when we include technology, because the variables involved in that are humongous. It isn't merely intelligence, but opposable thumbs (or similar), curiosity, etc.

Makes you wonder though why there wouldn't be some space faring species that have sufficient longevity for interstellar travel at sub-light speeds to be a doddle.

Well, this is certainly a possibility, but even a species with longevity is subservient to the distances, as detailed in the linked post. Of course, a suitable space-faring species can reduce the amount of 'in-time' if it can get to significant fractions of [math]c due to relativistic time dilation, but the cosmological time that passes will still be significant. Of course, there could be species whose entire lives are lived on the move in the depths of space, just going from one place to another so that returning anywhere becomes moot, but that's mere conjecture.

On the question of whether aliens might have visited earth, well, I have no problems with the notion of panspermia be that an impersonal process that arises normally within the evolution of the universe, or a case of our planet being seeded from afar via a sapient process. Problem is testing the notion, but that won't be impossible in the former scenario as there are zillions of comets within the Oort cloud that may turn up some clues sometime in the next few million years or so.

It also doesn't really solve any problems, because it just pushes abiogenesis off the planet.

But the main thread here seems to be whether sapient aliens have ever visited this planet, presumably in their space ships.

Let's put it this way, they either have or they haven't, and the evidence or lack of it for both propositions is subject to dispute.

Well, this is essentially correct, but with a minor alteration. The lack of evidence for its occurrence constitutes evidence for its non-occurrence. Usually at this point, somebody points to the famous Sagan quote, but what they actually end up doing is misrepresenting what he said, because what he was actually saying is pretty much what I've just said.

So it strikes me that the substantive argument here is whether the notion of the ET Hypothesis has been aptly named. Would it make a difference if it was called the ET Conjecture or the ET Proposition, and would the preceding nine pages of posts and arguments have occurred if it had been differently labelled?

Well, if you look at the other thread on 'ancient aliens', you'll see that the objections are somewhat more substantial. Certainly, though, it doesn't deserve the appellation 'hypothesis', simply because it isn't rooted in evidence

And just to throw a cat into the pigeons, I'm henceforth going to refer to String Theory as the String Conjecture until someone can demonstrate its testability.

I did that above. Sure, there are no practical tests we can conduct at the moment, but that was also the case for quantum tunnelling for a similar length of time as String Theory has been around, and since you are employing technology that relies upon quantum tunnelling for its operation, the objection is rendered moot.

So far I've liked this site, but at my welcome page I was warned that this site is a sometimes dysfunctional little family. That seems to arise from personal attacks and ridicule between discussants.

No, we don't do personal attacks. We do attack ideas ruthlessly, though. The basic principle is summed up nicely by Cali as follows:

Calilasseia wrote:I'll introduce you to the principle that is the current operating one here. Namely, that ideas are disposable entities, a notion that supernaturalists manifestly have particular trouble with. Furthermore, as a corollary of that principle, we contend that bad ideas exist to be destroyed. How do we determine what ideas are bad ideas? Simple. Ideas that either [1] are refuted by real world evidence (e.g., creationism), or [2] are manifestly the product of deranged flights of fancy (e.g., David Icke's ass-raping space lizards). On the other hand, anyone who comes up with a testable idea, a means of subjecting it to test, and evidence that said idea passes said test, is more than welcome to do so, and said ideas will be equally welcome.

Oh, and the forum lounge is that way. Chocolate gateau available on demand.

I don't agree with everything Landrew posts, but I agree even less with the ridicule that's aimed at him.

He hasn't had any ridicule aimed at him, but his ideas have. See above.

Welcome again. Hope you enjoy our little corner of the interwebz.

Isn't a theory generally "an integrated explanatory framework dealing with tried-and-tested hypotheses, observations and laws pertaining to a specific area of interest"? (I inserted 'tried-and-tested' there.)

Not really, because even untested hypotheses form part of the larger theory. Bear in mind that a theory actually generates hypotheses prior to their being tested, so there isn't a requirement for a hypothesis to be tested before integration into the broader theory.

Thanks for setting me straight there!

stijndeloose wrote:Thanks for setting me straight there!

I have to thank Hack,too.

I, too, had this "theory = successfully tested hypothesis" thing in mind, which is obviously wrong. Feeling a bit stupid now.

I'm just glad I wasn't the only one.

It's a common error, and one I was given to myself prior to being educated by the likes of susu.exp et al.

hackenslash wrote:

JungleDjinn wrote: In science, a theory is a hypothesis that's been validated, or perhaps I should say is a testable hypothesis that's not been falsified enough times that it becomes honoured with the promotion to a full scale "theory"

Not quite. A theory is an integrated explanatory framework dealing with all the hypotheses, observations and laws pertaining to a specific area of interest. Hypotheses don't get upgraded to theories, they're qualitatively different things.

So let's get down to defining our basic terms. I don't think you're accurate in describing hypotheses and theories as qualitatively different things, but I must admit to being taken aback that maybe I should check to ensure that I had a proper understanding of these terms. What I will do is resort to authoritative sources to help advance this argument:

[*] "A scientific hypothesis is an informed,testable, and predictive solution to a scientific problem that explains a natural phenomenon, process, or event" and

"A scientific theory is a unifying and self-consistent explanation of fundamental natural processes or phenomena that is totally constructed of corroborated hypotheses." - Steven D. Schafersman, Department of Geology, Miami University: http://www.geo.sunysb.edu/esp/files/sci ... ethod.html (Wikipedia uses this as its source for defining hypothesis and theory).

[*] "A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true." and

"A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis. " [my bolding] - Anne Marie Helmenstine, Ph.D at http://chemistry.about.com/od/chemistry ... theory.htm

[*] "A hypothesis is a working assumption. Typically, a scientist devises a hypothesis and then sees if it ``holds water'' by testing it against available data (obtained from previous experiments and observations). If the hypothesis does hold water, the scientist declares it to be a theory." - Jose Wudka at http://physics.ucr.edu/~wudka/Physics7/ ... node7.html

Hawking sees theories as hypotheses because they can never be proved: http://arash-farzaneh.suite101.com/hawk ... se-a292398

So what this seems to mean is that a hypothesis can graduate to become a theory once it is tested often enough. Conversely, theories can contain one or more tested and unfalsified hypotheses. The explanatory framework to which you refer is clearly needed if there is more than one hypothesis involved, otherwise the corroborated hypothesis can simply be upgraded to a scientific theory.

Clearly they are not qualitatively different, but are different and frequently overlapping stages of a process of modelling and predicting events.

(I'm skeptical of this process also, cf untestable String Theory (sic)

Well, there are certain postulates arising from M-Theory that are in principle testable and therefore falsifiable. Whether or not we have the means to test them now is a different matter, but they are testable. The existence of extra dimensions, for example, is testable, and I detailed in a previous post how that test might work. You'll find the relevant post here. Further, there is a cosmological model arising from M-Theory that is also in principle testable, namely the Turok/Steinhardt 'brane-worlds' model. Calilasseia has presented the papers in some detail here. As always, to ensure that I'm not misunderstood, I'm neither a supporter nor a detractor, preferring to wait until the evidence is in. To say that it isn't a theory, or that it is untestable and unfalsifiable, though, is simply wrong.

There's a huge gap between something being testable in practice and being testable in principle. The notion of the ST "landscape" illustrates that difference - there could be up to 10^500 string theories, and that is several hundred orders of magnitude greater than the number of neutrons that would exist if they packed the universe to capacity. Testable in principle yes, if we had the time that would be made available if the projected longevity universe was untold trillions of times longer than it is, so in practice - no, it's not testable.

I want to read your post about M-theory in detail so I can ensure I understand what it is you are saying before I respond, but I wanted to create a fairly quick reply to some of your points.

Personally I have no idea whether there are aliens out there or not, but Fermi's Paradox is a truly scary one to contemplate in all its complexity.

There's nothing complex about the Fermi paradox and, in fact, it isn't actually a paradox. It's also beautifully debunked by the Drake Equation, which I present in detail in the Equations Thread here

I don't see the debunking myself. The Fermi Paradox speaks of the universe, not just the galaxy. And the window of time you refer to in which to receive EM signals is only part of the story. Consider a metaphor: you are standing on a cliff top looking across a large seemingly pristine forest, and see no other human. Does this mean there is none? Of course not, especially if someone happens to shout, send smoke signals, or radio you during the period in which you are observing - that essentially sums up your scenario metaphorically speaking. But you might work out that there is someone there, or that someone was there once upon a time if you see a dwelling, a town or a city, or anything that is clearly non-random and has been subject to intelligent manipulation. Translate this to a stellar/galactic/universal scale and you can see the extension of this metaphor. We have access to information from around the universe from the beginning of time and space (for sake of argument), so the information that we can perceive can have been sent from anywhere between 13.7 billion years ago, to a fraction of a second ago. And yet in all that vastness, no verifiably non-random information indicating sentience/sapience has been observed. The fact that we've only been looking for 50 years or so is in fact irrelevant in this scheme - we are looking everywhere and everywhen - and there's nothing that we've noticed that would indicate any evidence of technological (ie: capable of manipulating and shaping the environment) intelligence.

The Drake Equation is well and good, but with so many variables of unknown value in the equation, it's not something to seriously rely upon.

If there is no life out there, WTF is that all about? Could we be the only ones in this enormous setup - how likely is that?

Certainly we could, but I deem it highly improbable. The simple fact, though, is that we don't properly understand all the variables, such as how many routes there might be to chemical abiogenesis and what sort of time-scales might be involved.

Agree. And how long would it take for abiogenesis to occur. We only need one successful occurrence of abiogenesis to kickstart life in the universe, but presumably there may be many.

Makes you wonder though why there wouldn't be some space faring species that have sufficient longevity for interstellar travel at sub-light speeds to be a doddle.

Well, this is certainly a possibility, but even a species with longevity is subservient to the distances, as detailed in the linked post. Of course, a suitable space-faring species can reduce the amount of 'in-time' if it can get to significant fractions of [math]c due to relativistic time dilation, but the cosmological time that passes will still be significant. Of course, there could be species whose entire lives are lived on the move in the depths of space, just going from one place to another so that returning anywhere becomes moot, but that's mere conjecture.

Exactly. Time and its passage may mean something utterly different to people living elsewhere.

On the question of whether aliens might have visited earth, well, I have no problems with the notion of panspermia be that an impersonal process that arises normally within the evolution of the universe, or a case of our planet being seeded from afar via a sapient process. Problem is testing the notion, but that won't be impossible in the former scenario as there are zillions of comets within the Oort cloud that may turn up some clues sometime in the next few million years or so.

It also doesn't really solve any problems, because it just pushes abiogenesis off the planet.

But if we do discover evidence in the Oort Cloud then it will solve some problems. Just might take some time...

But the main thread here seems to be whether sapient aliens have ever visited this planet, presumably in their space ships.

Let's put it this way, they either have or they haven't, and the evidence or lack of it for both propositions is subject to dispute.

Well, this is essentially correct, but with a minor alteration. The lack of evidence for its occurrence constitutes evidence for its non-occurrence. Usually at this point, somebody points to the famous Sagan quote, but what they actually end up doing is misrepresenting what he said, because what he was actually saying is pretty much what I've just said.

I don't see that's valid. Just because there is no evidence of someone having been in the room 5 minutes ago, doesn't mean they weren't. I'm not sure of the Sagan quote: did I just paraphrase it?

And just to throw a cat into the pigeons, I'm henceforth going to refer to String Theory as the String Conjecture until someone can demonstrate its testability.

I did that above. Sure, there are no practical tests we can conduct at the moment, but that was also the case for quantum tunnelling for a similar length of time as String Theory has been around, and since you are employing technology that relies upon quantum tunnelling for its operation, the objection is rendered moot.

Science is meant to be empirical. It's not enough for it to be empirical in principle, it has to be empirical in practice. ST has been going for 30 years and so far nothing has been tested. That is the longest time for a seriously dominant paradigm to be untested. Time to move on.

So far I've liked this site, but at my welcome page I was warned that this site is a sometimes dysfunctional little family. That seems to arise from personal attacks and ridicule between discussants.

No, we don't do personal attacks. We do attack ideas ruthlessly, though. The basic principle is summed up nicely by Cali as follows:

Calilasseia wrote:I'll introduce you to the principle that is the current operating one here. Namely, that ideas are disposable entities, a notion that supernaturalists manifestly have particular trouble with. Furthermore, as a corollary of that principle, we contend that bad ideas exist to be destroyed. How do we determine what ideas are bad ideas? Simple. Ideas that either [1] are refuted by real world evidence (e.g., creationism), or [2] are manifestly the product of deranged flights of fancy (e.g., David Icke's ass-raping space lizards). On the other hand, anyone who comes up with a testable idea, a means of subjecting it to test, and evidence that said idea passes said test, is more than welcome to do so, and said ideas will be equally welcome.

Oh, and the forum lounge is that way. Chocolate gateau available on demand.

OK...but

I don't agree with everything Landrew posts, but I agree even less with the ridicule that's aimed at him.

He hasn't had any ridicule aimed at him, but his ideas have. See above.

I observe some posts on this thread that are very close to ridiculing him, rather than his ideas. I personally did not find it edifying to read some of the more personal attacks

Welcome again. Hope you enjoy our little corner of the interwebz.

Thanks, and cheers also

Sort out your quote tags, please, so that I can respond properly without wasting 20 minutes doign it myself.

What is the difference between a hypothesis and conjecture
Is the former more grounded in what is already known and
the latter just mere speculation though not contradicting
what is already known : I remember Brain Cox saying a
conjecture was an educated guess so maybe that is it

hackenslash wrote:Sort out your quote tags, please, so that I can respond properly without wasting 20 minutes doign it myself.

Done

JungleDjinn wrote:So let's get down to defining our basic terms. I don't think you're accurate in describing hypotheses and theories as qualitatively different things, but I must admit to being taken aback that maybe I should check to ensure that I had a proper understanding of these terms. What I will do is resort to authoritative sources to help advance this argument:

[*] "A scientific hypothesis is an informed,testable, and predictive solution to a scientific problem that explains a natural phenomenon, process, or event" and

Nothing there that disagrees with me.

"A scientific theory is a unifying and self-consistent explanation of fundamental natural processes or phenomena that is totally constructed of corroborated hypotheses." - Steven D. Schafersman, Department of Geology, Miami University: http://www.geo.sunysb.edu/esp/files/sci ... ethod.html (Wikipedia uses this as its source for defining hypothesis and theory).

This is simply wrong, and so trivial to refute that I've already done so above. Theories generate hypotheses, which refutes wholesale this definition, because the hypotheses that are generated by theories cannot have been corroborated when they are generated.

[*] "A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true." and

Not sure why you keep adding these bits in, as they add nothing. This agrees with me.

"A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis. " [my bolding] - Anne Marie Helmenstine, Ph.D at http://chemistry.about.com/od/chemistry ... theory.htm

This is an authoritative source?

[*] "A hypothesis is a working assumption. Typically, a scientist devises a hypothesis and then sees if it ``holds water'' by testing it against available data (obtained from previous experiments and observations). If the hypothesis does hold water, the scientist declares it to be a theory." - Jose Wudka at http://physics.ucr.edu/~wudka/Physics7/ ... node7.html

This is incorrect. A hypothesis would not be declared a theory, it would be subsumed into a broader theory as an observation. Further, you snipped out the bit just before that that supports what I said, namely:

But to a scientist a theory is a conceptual framework that explains existing observations and predicts new ones.

Which actually refutes his second paragraph, because a single hypothesis cannot be a conceptual framework that explains existing observations and predicts new ones, nor can it be upgraded to one.

This source is woefully non-rigorous

Hawking sees theories as hypotheses because they can never be proved: http://arash-farzaneh.suite101.com/hawk ... se-a292398

A blog about Stephen Hawking, with nothing by Hawking himself? Really? I thought we were going to get authoritative source?

So what this seems to mean is that a hypothesis can graduate to become a theory once it is tested often enough.

Except that it can't, unless the hypothesis is broad enough in scope and autonomous enough to warrant a new are of enquiry. Only if a hypothesis makes multiple, independent predictions, all of which must be tested separately, can it ever get close to becoming a theory, because these predictions themselves constitute independent hypotheses. Indeed, it isn't far off the mark to think of a theory as a hypothesis-generating machine, because that's pretty much what it is.

Conversely, theories can contain one or more tested and unfalsified hypotheses. The explanatory framework to which you refer is clearly needed if there is more than one hypothesis involved, otherwise the corroborated hypothesis can simply be upgraded to a scientific theory.

As I said, only if they are broad enough in scope to generate multiple, independent hypotheses.

Clearly they are not qualitatively different,

Actually, they are qualitatively different, because one is simply a prediction, while the other is a set of predictions, both tested and untested, along with all the individual observations that have been made to test them, and all the laws that have been formulated from those hypotheses, observations, tests and laws. Hypotheses don't contain observations, tests or laws. This alone is sufficient to demonstrate the qualitative difference between them.

but are different and frequently occasionally overlapping stages of a process of modelling and predicting events.

FIFY. This is more accurate, and in fact agrees with what I was saying all along.

There's a huge gap between something being testable in practice and being testable in principle. The notion of the ST "landscape" illustrates that difference - there could be up to 10^500 string theories, and that is several hundred orders of magnitude greater than the number of neutrons that would exist if they packed the universe to capacity. Testable in principle yes, if we had the time that would be made available if the projected longevity universe was untold trillions of times longer than it is, so in practice - no, it's not testable.

Time is irrelevant, and in fact the claim that such time would be required is simply erroneous. I suggest that you might need to go and revisit your Popper. The reasons that M-Theory are currently beyond the reach of experiment stem from the fact that the mathematics is incomplete, because it is this incompleteness that generates such a broad landscape. Moreover, the length scales that we would need to probe are such that we would require particle accelerators on the scale of the solar system or larger to get anywhere near them. This has no bearing, however, on whether they are testable, because testable is testable, even if such tests are currently beyond our scope. Most importantly, though, the predictions arising from the 'brane-worlds' model, a product of M-Theory, are actually open experimentation with current technology, if we can build sensitive enough interferometers. The planned LISA space mission should be bring relevant observations within reach, if it gets off the ground.

Further, you really should have a look at the post in which I detail what would be required to test for small dimensions, which is very simple and extremely robust.

I don't see the debunking myself. The Fermi Paradox speaks of the universe, not just the galaxy.

Actually, you've just put a bigger nail in the coffin. The original statement of the Fermi paradox was 'where is everybody'. If the Drake Equation which, as you say, deals only with the galaxy, then the problem is exacerbated when you extend it to the scale of the universe, because when the Drake Equation is extended to the universe, the output population density plummets dramatically. This actually shoots the Fermi Paradox in the foot.

And the window of time you refer to in which to receive EM signals is only part of the story. Consider a metaphor: you are standing on a cliff top looking across a large seemingly pristine forest, and see no other human. Does this mean there is none? Of course not, especially if someone happens to shout, send smoke signals, or radio you during the period in which you are observing - that essentially sums up your scenario metaphorically speaking. But you might work out that there is someone there, or that someone was there once upon a time if you see a dwelling, a town or a city, or anything that is clearly non-random and has been subject to intelligent manipulation.

Oh look. It's fatuous bad analogy time.

Look, those signals need not have bee sent while we've been observing. Indeed, if they had, even from any more than 1/10th of 1% of the way across our own galactic disc, the they wouldn't have reached us yet. If a technological species that was transmitting EM signals only 10 light-years away had gone extinct only 90 years ago, we'd never, even in principle, know they'd bee there, because their signals would already be long gone before we had the capacity to detect them, or are you under the ridiculous illusion that once a radio signal has propagated to a place it simply hangs around?!! no, of course not, because photons can't stand still. This is basic stuff.

Translate this to a stellar/galactic/universal scale and you can see the extension of this metaphor. We have access to information from around the universe from the beginning of time and space (for sake of argument), so the information that we can perceive can have been sent from anywhere between 13.7 billion years ago, to a fraction of a second ago. And yet in all that vastness, no verifiably non-random information indicating sentience/sapience has been observed. The fact that we've only been looking for 50 years or so is in fact irrelevant in this scheme - we are looking everywhere and everywhen - and there's nothing that we've noticed that would indicate any evidence of technological (ie: capable of manipulating and shaping the environment) intelligence.

No, that 50 years is entirely relevant, because EM signals travel. There are some other things to note here, namely that life didn't exist 13.7 billion years ago anywhere, because life required the existence of second-generation stars at a minimum. If a technological species exists at the edge of our light horizon right now, we will ever know it, because it will take 13.7 billion years for their signals to cover the distance between them and us, by which time we'll be even further apart. Go read up on the 'horizon problem' for more info.

The Drake Equation is well and good, but with so many variables of unknown value in the equation, it's not something to seriously rely upon.

It is something to be relied upon, as log as you are careful to note what it's supposed to be telling us, namely the unknown variables of which you speak.

Agree. And how long would it take for abiogenesis to occur. We only need one successful occurrence of abiogenesis to kickstart life in the universe, but presumably there may be many.

Almost assuredly, but that doesn't equate to certainty, and it definitely doesn't equate to the certain existence of technological civilisations, because there are more variables involved in that that we have no way to address.

I don't see that's valid. Just because there is no evidence of someone having been in the room 5 minutes ago, doesn't mean they weren't. I'm not sure of the Sagan quote: did I just paraphrase it?

Well, Sagan is often quoted as saying 'absence of evidence is not evidence of absence'. However, what he was actually doing was warning against such fatuous statements, as they constitute a argument from ignorance. The full quote is as follows:

• Appeal to ignorance - the claim that whatever has not been proved false must be true, and vice versa (e.g., there is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist - and there is intelligent life elsewhere in the Universe. Or: there may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we're still central to the Universe). This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence.

Science is meant to be empirical. It's not enough for it to be empirical in principle, it has to be empirical in practice. ST has been going for 30 years and so far nothing has been tested. That is the longest time for a seriously dominant paradigm to be untested. Time to move on.

I refer you back to the technology that makes your computer work. Quantum tunnelling was also untested for a similar length of time before Leo Esaki devised the Esaki diode. The time to move on is when the theory is falsified. At the moment, it is rooted in observation, because it stems from well-founded scientific principles, albeit with some mathematical extrapolation that has taken it into the realm of the untested. This is how science proceeds.

I observe some posts on this thread that are very close to ridiculing him, rather than his ideas. I personally did not find it edifying to read some of the more personal attacks

You've just re-erected the same assertion that I already debunked. There were no attacks on his person, only on the fatuous drivel he was posting.

surreptitious57 wrote:What is the difference between a hypothesis and conjecture? Is the former more grounded in what is already known and the latter just mere speculation though not contradicting what is already known?

Pretty much. A conjecture (in science; there is a little variation when applied in mathematics) is essentially a statement that is thought to be true, though not necessarily actually testable, even in principle. For example, the statement 'the cosmos is 156 Gly across' is a conjecture, because we can think of no way to empirically test it.

: I remember Brain Cox saying a conjecture was an educated guess so maybe that is it

Yep.

hackenslash - Fine, you win. So long and thanks for the discussion.

It's not about 'Winning' It's about Explaining!