RainOfSteel
SOC-14 1K
That was my understanding in general, and I assure one and all that the above was the context I used the word in.
Universe might be bigger and older than previously thought
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princelian
SOC-12
I believe Aramis was trying to convey humor, not insult, Mal. That's my conjecture, anyhow.
It can't be a hypothesis, because I really can't test it. Nor, because I want peace and harmony on CotI, do I wish to test it. That would involve spanging potential insults at people and measuring the effect.
And now I've ruined it anyway because now you're all aware of the test. I'd want at least a single blind to get a reasonably accurate result, and double or triple would be better.
However, on to universes....
I really liked the analogy of the inflating sphere with the physical universe in 2D on the surface. I'll have to remember that the next time someone asks me "how can the universe be >100 billion LY across if it's only 13+ billion years old and you can't exceed the speed of light?" No one is very likely to ask (I have a dearth of physics-interested friends, unfortunately), but I'll have an illustration prepped for that happy discussion.
J-space, then, allows you to "tunnel" through from point to point on that surface without having to go "around," and the deeper you go into the sphere, the faster your trip, even if it's just a few millionths of a degree along the sphere's surface.
The geometry of the INSIDE of that sphere, now, THAT'S a toughie, but we know that you can't exceed J-6 and it always takes a week to tunnel down and back.
It can't be a hypothesis, because I really can't test it. Nor, because I want peace and harmony on CotI, do I wish to test it. That would involve spanging potential insults at people and measuring the effect.
And now I've ruined it anyway because now you're all aware of the test. I'd want at least a single blind to get a reasonably accurate result, and double or triple would be better.
However, on to universes....
I really liked the analogy of the inflating sphere with the physical universe in 2D on the surface. I'll have to remember that the next time someone asks me "how can the universe be >100 billion LY across if it's only 13+ billion years old and you can't exceed the speed of light?" No one is very likely to ask (I have a dearth of physics-interested friends, unfortunately), but I'll have an illustration prepped for that happy discussion.
J-space, then, allows you to "tunnel" through from point to point on that surface without having to go "around," and the deeper you go into the sphere, the faster your trip, even if it's just a few millionths of a degree along the sphere's surface.
The geometry of the INSIDE of that sphere, now, THAT'S a toughie, but we know that you can't exceed J-6 and it always takes a week to tunnel down and back.
M
Malenfant
Guest
Wasn't there a topic a short while ago (perhaps more than one) about playing nice? </font>[/QUOTE]I don't see anything "not nice" about what I said. I call it anti-science crap that he's spouting because that's exactly what it is. Aramis has a history of trying to put down and undermine science based on flawed assumptions about how it works. Now I see he's doing it again, I'm not allowed to call him on it and point out how and why he's wrong?
And people wonder why I don't post science stuff here anymore.
Gaming Glen
SOC-12
Originally posted by Malenfant:
And people wonder why I don't post science stuff here anymore.
But I love science stuff.
Wait. I have a hypothesis: The person known as Malenfant is a storehouse of scientific knowledge. Now, I just need more data to confirm it.
M
Malenfant
Guest
Originally posted by Gaming Glen:
</font><blockquote>quote:</font><hr />Originally posted by Malenfant:
And people wonder why I don't post science stuff here anymore.
But I love science stuff.
Wait. I have a hypothesis: The person known as Malenfant is a storehouse of scientific knowledge. Now, I just need more data to confirm it.
[/QB]</font>[/QUOTE]I'll be posting it on the Comstar/Avenger TAS boards. And lots more on the Spica project boards at SPL, if you can get into those (though they're not open to the public, IIRC).
Sounded more like a personal attack.
I was posting a practical definition... in response to someone's assertion that the theory in question was conjecture, not a hypothesis.
It's both.
Of course, your post looks like, was taken as, and has been reported as, a personal attack.
I was posting a practical definition... in response to someone's assertion that the theory in question was conjecture, not a hypothesis.
It's both.
Contradictory data is, axiomatically, inconclusive.
Of course, your post looks like, was taken as, and has been reported as, a personal attack.
M
Malenfant
Guest
Nice try. Only problem is that there's no "personal attack" in there at all - you have been and are anti-science, your post was very cynical dig at the scientific process, and that's what I called it as.
But again, it seems to be OK here for you to spout your nonsense about how flawed you think science is, but not OK for me to tell people that you're wrong and show them how you're deliberately misleading people.
You could have explained the difference a hell of a lot better without resorting to your inaccurate "devil's dictionary" version that you posted. But since you have an anti-science agenda you just went ahead and posted your cynical garbage as fact.
I mean, where the hell do you get off by slandering the scientific community and what it does all the time? And why the hell should I sit by and let you do that? I may not be a professional scientist by career anymore, but that doesn't make me any less of a scientist in how I think or act or what I do. So I'll stand up and defend science no matter what, and I'll damn well take it personally when people like you try to slander and undermine it.
But again, it seems to be OK here for you to spout your nonsense about how flawed you think science is, but not OK for me to tell people that you're wrong and show them how you're deliberately misleading people.
You could have explained the difference a hell of a lot better without resorting to your inaccurate "devil's dictionary" version that you posted. But since you have an anti-science agenda you just went ahead and posted your cynical garbage as fact.
I mean, where the hell do you get off by slandering the scientific community and what it does all the time? And why the hell should I sit by and let you do that? I may not be a professional scientist by career anymore, but that doesn't make me any less of a scientist in how I think or act or what I do. So I'll stand up and defend science no matter what, and I'll damn well take it personally when people like you try to slander and undermine it.
RainOfSteel
SOC-14 1K
I would just like to say for the record that I found nothing anti-science or slanderous in Aramis' post in question.
I felt it was referring, though only in the most indirect manner, to what I said in a slightly out of context way, but then nothing is perfect in this world.
I'm not going to ask how "agenda's" suddenly crept into this.
I felt it was referring, though only in the most indirect manner, to what I said in a slightly out of context way, but then nothing is perfect in this world.
I'm not going to ask how "agenda's" suddenly crept into this.
M
Malenfant
Guest
OK, I'll break it down then.
- Is Aramis' statement quoted above even a dictionary definition of hypothesis? No. So why is it being passed off as a legitimate definition of the word?
- "Conjecture"? No, a hypothesis is not a conjecture at all. A conjecture is what Aramis would claim and has claimed is "a wild-ass guess". That's not how science works.
I've explained it before, but I'll explain it again. It's basically like what most of you should have done in school in science class - you start with a hypothesis, come up with an experiment, get the results, come to a conclusion and see whether your hypothesis is valid or not. If the hypothesis fits the data, then you can refine it and expand it and test it further. If it doesn't, then you have to modify the hypothesis so that it does fit the data. But either way, the initial hypothesis is not by any means a "wild ass guess" (again, Aramis' words, not mine) - it's usually an educated guess at the very least, usually based on previous observations.
-"...which has survived peer review and/or oversight committee review"? No. A hypothesis is still a hypothesis regardless of whether it has been peer-reviewed.
-"...fits the available data". Well at least he got something right.
-"...and is worthy of testing"? Again, no. There's no "worth" involved on a purely scientific level - if a hypothesis is testable, it's worth testing. The only place that "worth" comes in is from a financial perspective, because money is so tight that we have to scrabble for grants and claim that "my science is better than their science" to the research councils so we can grab at the scraps of money thrown our way. Either way, from a purely scientific perspective hypotheses aren't tested based on their "worthiness", they're tested based on whether we can get data and observations to get a meaningful result.
Put all that together, along with Aramis' previously demonstrated hostility towards the scientific method and the knowledge acquired by it, and the way he phrased the whole thing as if it were fact rather than his opinion or interpretation of fact (which it obviously is) and it's not surprising that I took it as an "anti-science statement". His one sentence is riddled with inaccuracy and opinion, stated as fact when it's not.
- "Sci-speak"? What's this "sci-speak"? Do scientists have a secret language now that uses the same common words that English uses but with different meanings? Do we have any agenda to hide information from the public in this way? No. A hypothesis as defined in science is exactly the same as a hypothesis you'd find defined in a common dictionary.
- Is Aramis' statement quoted above even a dictionary definition of hypothesis? No. So why is it being passed off as a legitimate definition of the word?
- "Conjecture"? No, a hypothesis is not a conjecture at all. A conjecture is what Aramis would claim and has claimed is "a wild-ass guess". That's not how science works.
I've explained it before, but I'll explain it again. It's basically like what most of you should have done in school in science class - you start with a hypothesis, come up with an experiment, get the results, come to a conclusion and see whether your hypothesis is valid or not. If the hypothesis fits the data, then you can refine it and expand it and test it further. If it doesn't, then you have to modify the hypothesis so that it does fit the data. But either way, the initial hypothesis is not by any means a "wild ass guess" (again, Aramis' words, not mine) - it's usually an educated guess at the very least, usually based on previous observations.
-"...which has survived peer review and/or oversight committee review"? No. A hypothesis is still a hypothesis regardless of whether it has been peer-reviewed.
-"...fits the available data". Well at least he got something right.
-"...and is worthy of testing"? Again, no. There's no "worth" involved on a purely scientific level - if a hypothesis is testable, it's worth testing. The only place that "worth" comes in is from a financial perspective, because money is so tight that we have to scrabble for grants and claim that "my science is better than their science" to the research councils so we can grab at the scraps of money thrown our way. Either way, from a purely scientific perspective hypotheses aren't tested based on their "worthiness", they're tested based on whether we can get data and observations to get a meaningful result.
Put all that together, along with Aramis' previously demonstrated hostility towards the scientific method and the knowledge acquired by it, and the way he phrased the whole thing as if it were fact rather than his opinion or interpretation of fact (which it obviously is) and it's not surprising that I took it as an "anti-science statement". His one sentence is riddled with inaccuracy and opinion, stated as fact when it's not.
TheEngineer
SOC-14 1K
Hi !
Peace !.
Calm down, everybody.
I cvan understand rising hostility, but not towards scientific methods, but towards pretty negative examples of scientific practice, which become appearent during the last couple of years and produced enough bad press.
Sadly todays science is willingly or unwillingly coupled with business and there are enough people willing to "set up some hypothesis" in order to create interest and get financial support, "come up with an experiment", which makes sense and oh, wonder, creates results they needed.
But thats no longer science but just bad or criminal business.
In this context A's remark is understandable, but as I said, its IMHO not against science but bad practice.
Taking high end theoretical astrophysics many hypothesis suffer from, that its not or just hardly possible to set up any experiments to test them. That turns many - maybe serious meant hypothesis - into guesses.
But, in order to protect the status of scientists just look at this little extract from "The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang" by Khoury1, Ovrut, Steinhardt and Neil Turok :
Anyway, the quality of this board depends on the existence and the quality of scientific remarks.
We deal with Science Fiction, and if we would start to loose the science part here, we would loose the backbone of Traveller.
So anybody please dont stop to post stuff, regardless if its a well known fact, a full featurered hypothesis or even just a "wild ass guess" (sometimes we have no approriate words in german language to express such meanings so compact
).
Regards,
TE
Peace !.
Calm down, everybody.
I cvan understand rising hostility, but not towards scientific methods, but towards pretty negative examples of scientific practice, which become appearent during the last couple of years and produced enough bad press.
Sadly todays science is willingly or unwillingly coupled with business and there are enough people willing to "set up some hypothesis" in order to create interest and get financial support, "come up with an experiment", which makes sense and oh, wonder, creates results they needed.
But thats no longer science but just bad or criminal business.
In this context A's remark is understandable, but as I said, its IMHO not against science but bad practice.
Taking high end theoretical astrophysics many hypothesis suffer from, that its not or just hardly possible to set up any experiments to test them. That turns many - maybe serious meant hypothesis - into guesses.
But, in order to protect the status of scientists just look at this little extract from "The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang" by Khoury1, Ovrut, Steinhardt and Neil Turok :
See, everybody is sure of the actual state of development, but sometimes its just neccesary to present speculative stuff in science, too in order to push things forward and to create new motivations.
Anyway, the quality of this board depends on the existence and the quality of scientific remarks.
We deal with Science Fiction, and if we would start to loose the science part here, we would loose the backbone of Traveller.
So anybody please dont stop to post stuff, regardless if its a well known fact, a full featurered hypothesis or even just a "wild ass guess" (sometimes we have no approriate words in german language to express such meanings so compact
Regards,
TE
far-trader
SOC-14 10K
I hate to speak up and be labled by you Mal as a personal enemy and hater of science* but I've got to agree with RoS and probably others who are remaining silent on this (more wisely so than myself).
* of which I'm not either but you seem to be going to extremes of late
I too didn't see this as any attack, personal or anti-science, previous possible (I don't recall) bias or not on Aramis' part. It read to me as simply an attempt to put it into layman's terms.
To borrow your own breakdown method:
"Sci-speak" - Admit it, science does employ a jargon, most professions do, and the words do not always fit the layman's vocabulary. Hypothesis is one of those words.
"Is Armamis' definition a dictionary definition" - Pretty close really, but he was aiming for a layman's definition. My handiest dictionary has this as one definition (bracket notes mine) "An assumption (synonym of conjecture) or assumptions provisionally accepted (survived peer review, fits the available data), especially as a basis for further investigation (and is worthy of testing)." Really quite spot on to Aramis' I'd say.
"Conjecture? No, a hypothesis is not a conjecture at all" - Yes. Conjecture, another synonym of Hypothesis. A hypothesis IS conjecture.
"Worthy of testing" - You yourself use "worth testing" in the very sentence you deny Aramis the use of "worth" testing as a measure of a hypothesis. Put it this way: A hypothesis that is found to fail tests is not worth further tests. One that has passed tests is worth further tests, if for no other reason than to independantly validate the other tests. That's peer review isn't it.
And finally...
It is easy to see you took it, incorrectly I think, as anti-science and even personally, based largely if not solely on prejudice developed from previous encounters, which to my mind is not very open minded. Understandable sure, forgivable certainly, even expected to a degree. It's still not that acceptable when you go on about it and respond with personal attacks. Yes personal attacks. At least to the mind of a few, including the one they were directed to. You don't seem to see it though, and yet I get the strong feeling you felt personally attacked by Aramis' statement where I don't see it.
I'm worried for your calm friend, and your continued good presence here on CotI. You need to take a step back, a deep breath, and count to 10 after some of these "trigger posts" I've seen you reply to here lately. They aren't really out to get you or science as much as you seem to imagine. Not that I've seen here lately at least. Out there elsewhere, daily in the news, and in a now defunct forum here, yes. There are ignorant savages that Darwinism should have culled ages ago but for the fact that science keeps saving them in spite of themselves, because that's how science works. That's one of the ironies of life that I detest and yet still find amusing. I pray to God that science wins the tussle and eventually finds a permanent cure for them all.*
* just more irony, so thickly knotted you might need Alexander himself to cut through it
Well, I've taken this far enough off topic. If it's drifted into the realm of "here there be MODERATORS" who devour such posts whole or snack on bits of them then so be it. I'm just trying to help.
To post or not to post? Tough question. Obvious answer though not swiftly reached. Hope it was the right one...
* of which I'm not either but you seem to be going to extremes of late
I too didn't see this as any attack, personal or anti-science, previous possible (I don't recall) bias or not on Aramis' part. It read to me as simply an attempt to put it into layman's terms.
To borrow your own breakdown method:
"Sci-speak" - Admit it, science does employ a jargon, most professions do, and the words do not always fit the layman's vocabulary. Hypothesis is one of those words.
"Is Armamis' definition a dictionary definition" - Pretty close really, but he was aiming for a layman's definition. My handiest dictionary has this as one definition (bracket notes mine) "An assumption (synonym of conjecture) or assumptions provisionally accepted (survived peer review, fits the available data), especially as a basis for further investigation (and is worthy of testing)." Really quite spot on to Aramis' I'd say.
"Conjecture? No, a hypothesis is not a conjecture at all" - Yes. Conjecture, another synonym of Hypothesis. A hypothesis IS conjecture.
"Worthy of testing" - You yourself use "worth testing" in the very sentence you deny Aramis the use of "worth" testing as a measure of a hypothesis. Put it this way: A hypothesis that is found to fail tests is not worth further tests. One that has passed tests is worth further tests, if for no other reason than to independantly validate the other tests. That's peer review isn't it.
And finally...
Disregard previously demonstrated hostility (again I just don't recall it and can't say there was or wasn't), there is none implied or specific in that statement taken at face value. Neither does it seem phrased as fact rather than opinion in that light. And it is not riddled with with inaccuracy as I've shown.
It is easy to see you took it, incorrectly I think, as anti-science and even personally, based largely if not solely on prejudice developed from previous encounters, which to my mind is not very open minded. Understandable sure, forgivable certainly, even expected to a degree. It's still not that acceptable when you go on about it and respond with personal attacks. Yes personal attacks. At least to the mind of a few, including the one they were directed to. You don't seem to see it though, and yet I get the strong feeling you felt personally attacked by Aramis' statement where I don't see it.
I'm worried for your calm friend, and your continued good presence here on CotI. You need to take a step back, a deep breath, and count to 10 after some of these "trigger posts" I've seen you reply to here lately. They aren't really out to get you or science as much as you seem to imagine. Not that I've seen here lately at least. Out there elsewhere, daily in the news, and in a now defunct forum here, yes. There are ignorant savages that Darwinism should have culled ages ago but for the fact that science keeps saving them in spite of themselves, because that's how science works. That's one of the ironies of life that I detest and yet still find amusing. I pray to God that science wins the tussle and eventually finds a permanent cure for them all.*
* just more irony, so thickly knotted you might need Alexander himself to cut through it
Well, I've taken this far enough off topic. If it's drifted into the realm of "here there be MODERATORS" who devour such posts whole or snack on bits of them then so be it. I'm just trying to help.
To post or not to post? Tough question. Obvious answer though not swiftly reached. Hope it was the right one...
M
Malenfant
Guest
Well, I've described how I took what he said as an anti-science slur. Maybe that's not how he intended it, but that's how it came out to me, and I feel entirely justified in taking it that way given his previous attitude. His definition was not remotely carefully considered and nor was it even accurate either. (and again, you're wrong about the jargon. Hypothesis means the same in scientific terms as it does in general english. Claiming otherwise is simply incorrect).
And no, I didn't even remotely "personally attack" him. Unless he's got an incredibly thin skin (which a lot of people here seem to have).
Again though, I have to wonder how a post pointing out a scientific observation yet again devolves into an argument about what science is and how it works, and that was starting even before Aramis came along. And yet again, I realise I'm wasting my time here trying to defend science, and am further discouraged from posting anything about the subject myself. Or about anything at all, for that matter.
Come to think of it, there are better Traveller boards to be on nowadays. I think I'll be spending a lot more time on those boards than on this one from now on. I'm getting tired of putting up with the same old crap from the same people all the time here.
And no, I didn't even remotely "personally attack" him. Unless he's got an incredibly thin skin (which a lot of people here seem to have).
Again though, I have to wonder how a post pointing out a scientific observation yet again devolves into an argument about what science is and how it works, and that was starting even before Aramis came along. And yet again, I realise I'm wasting my time here trying to defend science, and am further discouraged from posting anything about the subject myself. Or about anything at all, for that matter.
Come to think of it, there are better Traveller boards to be on nowadays. I think I'll be spending a lot more time on those boards than on this one from now on. I'm getting tired of putting up with the same old crap from the same people all the time here.
oTay iam gonna add gas to the "scientific fire"
one, i havent understood one thing said
in anyones post about the science stuff
"thank God"
but i am wondering who made mal the
science discussion police with the
liscense to kill?
i think, mal, your response to aramias
statment shows a deeper animosity towords
aramias then his statement warrented...
it might be time to go cool off somewheres
maybe even avoid repsonding to each others
posts for awhile regardless of content...
M
Malenfant
Guest
And I rest my case, my point proven.
Seeya folks. Have fun making up stuff about science!
Seeya folks. Have fun making up stuff about science!
Border Reiver
SOC-14 1K
TheEngineer
SOC-14 1K
Andrew Boulton
The Adminator
Everybody calm down or I'll start Moderating.
And there you have it ladies and gentlemen: The big bang.
Moving back to the topic.
I loved Princelian's idea of using this to explain jumpdrives
It is now believed that the Universe is large enough that there can be areas A and B that have not been able to exchange light.
This is a result of recent observations that indicate that the rate of the Universe's expansion is speeding up, contrary to what astronomers were expecting a couple of years ago.
Which leads onto this:
The Question
(Submitted June 30, 1997)
I'm a college graduate with a degree in computer science. However, my favorite pastime has always been reading about astronomy, quantum mechanics, etc. that's my background. My question is:
When astronomers speak of the estimated size of the "known Universe", are they setting this distance (from us) based upon the furthest visible object, or upon calculation? This is in reference to the fact that quasars (as far as I know) are the furthest observable objects. Yet they travel at speeds approaching that of light away from us. Obviously, if there was anything further than the distance at which the expansion of the Universe = c, it would be impossible for us to detect it, now or ever. To sum up the question: how can one estimate the size of the Universe if any part of it past this critical distance is forever cut off from our measurement? One could argue that since we cannot ever reach these locations, for us they do not exist, but I think that's a horrible cop-out.
The Answer
What astronomers mean when they speak of the "known Universe" depends on the astronomer. Most often it refers to the region of the Universe from which light could travel to us since shortly after the Big Bang.
The farthest observable discrete objects are the quasars (visible at such great distances because they are so bright). However, the cosmic microwave background radiation, at 3 degrees Kelvin, comes from even further away. It has a redshift of about 1000, and comes from the time when the Universe was much smaller, and filled with hot ionized gas (plasma) at 3000 Kelvin, as hot as the surface of some stars. Dense plasma blocks light, and so we cannot see anything beyond that distance.
If the theory known as "inflation" is true, the size of the "known Universe" is much smaller than that of the Universe as a whole. If you look at the "known Universe", every part of it looks about the same, as far as we can tell. As an analogy, if you look at a typical cornfield in Kansas, it all looks the same as far as the eye can see. For there to be as much variety as you would expect in a world, the world has to be much larger than the size of a Kansas cornfield. Likewise, inflation says that the Universe is much larger than the known Universe.
How much larger is hard to determine, and theories are untrustworthy since we can never confirm them by observations. (Actually, 'never' is a bit of an overstatement. If you waited long enough, the Universe would slow its expansion and you may be able to see a bit further. But that would take billions of years.)
All taken from here: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970630c.html
Moving back to the topic.
I loved Princelian's idea of using this to explain jumpdrives
I found another explanation which was also really good:
It is now believed that the Universe is large enough that there can be areas A and B that have not been able to exchange light.
This is a result of recent observations that indicate that the rate of the Universe's expansion is speeding up, contrary to what astronomers were expecting a couple of years ago.
Which leads onto this:
The Question
(Submitted June 30, 1997)
I'm a college graduate with a degree in computer science. However, my favorite pastime has always been reading about astronomy, quantum mechanics, etc. that's my background. My question is:
When astronomers speak of the estimated size of the "known Universe", are they setting this distance (from us) based upon the furthest visible object, or upon calculation? This is in reference to the fact that quasars (as far as I know) are the furthest observable objects. Yet they travel at speeds approaching that of light away from us. Obviously, if there was anything further than the distance at which the expansion of the Universe = c, it would be impossible for us to detect it, now or ever. To sum up the question: how can one estimate the size of the Universe if any part of it past this critical distance is forever cut off from our measurement? One could argue that since we cannot ever reach these locations, for us they do not exist, but I think that's a horrible cop-out.
The Answer
What astronomers mean when they speak of the "known Universe" depends on the astronomer. Most often it refers to the region of the Universe from which light could travel to us since shortly after the Big Bang.
The farthest observable discrete objects are the quasars (visible at such great distances because they are so bright). However, the cosmic microwave background radiation, at 3 degrees Kelvin, comes from even further away. It has a redshift of about 1000, and comes from the time when the Universe was much smaller, and filled with hot ionized gas (plasma) at 3000 Kelvin, as hot as the surface of some stars. Dense plasma blocks light, and so we cannot see anything beyond that distance.
If the theory known as "inflation" is true, the size of the "known Universe" is much smaller than that of the Universe as a whole. If you look at the "known Universe", every part of it looks about the same, as far as we can tell. As an analogy, if you look at a typical cornfield in Kansas, it all looks the same as far as the eye can see. For there to be as much variety as you would expect in a world, the world has to be much larger than the size of a Kansas cornfield. Likewise, inflation says that the Universe is much larger than the known Universe.
How much larger is hard to determine, and theories are untrustworthy since we can never confirm them by observations. (Actually, 'never' is a bit of an overstatement. If you waited long enough, the Universe would slow its expansion and you may be able to see a bit further. But that would take billions of years.)
All taken from here: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970630c.html
princelian
SOC-12
I would have to say, ravs, that if it is true that the universe is larger than can see, that all of the theories about the universe expanding or contracting, and the theories about the origin of the universe, are called into question.
I'll try to illustrate what I'm trying to say (poorly; I'm a physical chemist, not an astrophysicist, although I certainly have a great interest in astrophysics).
If you grew up in a tribe on a desert island far removed from the rest of the world, and in a part of the ocean where the currents and weather made it unlikely you'll ever see any other living creature, you would make certain assumptions on how the world works. The ocean is infinitely deep (except near the island) and infinitely wide. It also occasionally eats members of your tribe, whether by weather, accident, or pointy-toothed fishes.
The highest point of the island is a few hundred meters, so the world is mostly flat.
It's always warm except during storms, and then it's warm again.
Food always grows, year-round. Fish are always there.
This is the universe, as perceived by the tribesmen. They have no concept - cannot HAVE a concept - of mountains. Of snow. Of forests that aren't tropical plants.
Conifers? What are those?
So it might be with the universe. We see 13.6 billion LY in all directions but what's 13.7 billion LY away? Actually, we can see beyond that distance indirectly, because we could - if we're clever enough - see the gravitational effects on distant objects that are coming from even more distant objects. It's hard to get parallax at that distance, though, so it'd have to be some pretty massive gravity sources.
But even indirectly, there's a finite limit to how far we can see, and maybe *just* beyond that is a mountain. Or snow. Or types of stars that we've never even conceived of. Or living galaxies that are waving at us but we can't see it. (Okay, I've stepped beyond sci-fi to fantasy, sorry.)
The point is that if the universe is larger than we can perceive, we can't really characterize anything but the "local" universe. (Strange indeed to call 4.2 billion parsecs "local," but, well, the universe is BIG.)
I'll try to illustrate what I'm trying to say (poorly; I'm a physical chemist, not an astrophysicist, although I certainly have a great interest in astrophysics).
If you grew up in a tribe on a desert island far removed from the rest of the world, and in a part of the ocean where the currents and weather made it unlikely you'll ever see any other living creature, you would make certain assumptions on how the world works. The ocean is infinitely deep (except near the island) and infinitely wide. It also occasionally eats members of your tribe, whether by weather, accident, or pointy-toothed fishes.
The highest point of the island is a few hundred meters, so the world is mostly flat.
It's always warm except during storms, and then it's warm again.
Food always grows, year-round. Fish are always there.
This is the universe, as perceived by the tribesmen. They have no concept - cannot HAVE a concept - of mountains. Of snow. Of forests that aren't tropical plants.
Conifers? What are those?
So it might be with the universe. We see 13.6 billion LY in all directions but what's 13.7 billion LY away? Actually, we can see beyond that distance indirectly, because we could - if we're clever enough - see the gravitational effects on distant objects that are coming from even more distant objects. It's hard to get parallax at that distance, though, so it'd have to be some pretty massive gravity sources.
But even indirectly, there's a finite limit to how far we can see, and maybe *just* beyond that is a mountain. Or snow. Or types of stars that we've never even conceived of. Or living galaxies that are waving at us but we can't see it. (Okay, I've stepped beyond sci-fi to fantasy, sorry.)
The point is that if the universe is larger than we can perceive, we can't really characterize anything but the "local" universe. (Strange indeed to call 4.2 billion parsecs "local," but, well, the universe is BIG.)
Nice analogy!
I think what the physicist is trying to say is that at one time (n billion years ago), light from any part of the universe could reach any other part of the universe, but if inflation theory is right then now (n billion years on) space in the far reaches of the universe is being created at a rate faster than the speed of light, so that anything beyond it is outside our realm of causality.
If this is true there must be a point on that edge where if you were observed from here, your image would never, ever change as you would be travelling away from earth at the speed of light!
How cool would that be? Immortality! Well at least as far as your observers are concerned.
Ravs
I think what the physicist is trying to say is that at one time (n billion years ago), light from any part of the universe could reach any other part of the universe, but if inflation theory is right then now (n billion years on) space in the far reaches of the universe is being created at a rate faster than the speed of light, so that anything beyond it is outside our realm of causality.
If this is true there must be a point on that edge where if you were observed from here, your image would never, ever change as you would be travelling away from earth at the speed of light!
How cool would that be? Immortality! Well at least as far as your observers are concerned.
Ravs
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