I’ve been following Alicorn’s sequence on luminousness, that is, on getting to know ourselves better. I had lowered my estimate of my own rationality when she mentioned that we tend to think too highly of ourselves, but now I can bump my estimate back up. There is at least one belief which my tribe elevates to the rank of scientific fact, yet which I think is probably wrong: I do not believe in the Big Bang.
Of course, I don’t believe the universe was created a few thousand years ago either. I don’t have any plausible alternative hypothesis, I just think that the arguments I have read in the many popular science physics book I have read are inconclusive.
First, these books usually justify the Big Bang theory as follows. Right now, it is an observable fact that stars are currently moving away from each other. Therefore, there was a time in the past where they were much closer. Therefore, there was a time where all the stars in the universe occupied the same point. It is this last “therefore” which I don’t buy: there is no particular reason to assume that if the stars are moving away from each other right now, then they must always have done so. They could be expanding and contracting in a sort of sine wave, or something more complicated.
Second, the background radiation which is said to be leftover stray photons from the big bang. If the background radiation was a prediction of Big Bang theory, then I might have been convinced by this experimental evidence, but in fact the background radiation was discovered by accident. Only afterwards did the proponents of Big Bang theory retrofit it as a prediction of their model.
Third, the acceleration. The discovery that the expansion was accelerating was a surprise to the scientific community. In particular, it was not predicted by Big Bang theory, even though it seems like the kind of thing which an explanatory model of the expansion of the universe should have predicted right away.
Fourth, the inflation phase. This part was added later on, once it had been observed that Big Bang theory did not fit with the observed homogeneousness of the cosmos. To me, this seems like a desperate and ad hod attempt to fix a broken theory.
Now, it could be that all these changes are a progression of refinements, just like Newtonian physics was adjusted to take into account the effects of relativity, and just like the spherical Earth was adjusted to make it an elliptical Earth. But the adjustments which Big Bang theory has suffered seem like they should change the predictions completely, rather than, as in the other cases, increasing the precision of the existing theory.
I am, of course, open to being convinced otherwise. If Big Bang theory really is true, then I wish to believe it is true.
There is no particular reason to assume that if the stars are moving away from each other right now, then they must always have done so. They could be expanding and contracting in a sort of sine wave, or something more complicated.
The key is there at the end of your quote. From the first set of observations (of relatively close galaxies), the simplest behavior that explained the observations was that everything was flying apart fast enough to overcome gravity. This predicted that when they had the technology to look at more distant galaxies, these too should be flying away from us, and at certain rates depending on their distance.
When we actually could observe those more distant galaxies, we did in fact see them red-shifted as predicted. This alone should be enough to put the “sine wave” theory in the epistemic category of “because the Dark Lords of the Matrix like red shifts”, because the light left these galaxies at all different times! It would take a vast conspiracy for them all to line up as red-shifted right now, from our perspective.
With strong evidence in hand that the galaxies had been flying apart for billions and billions of years, the scientists then noticed an irregularity: the velocities of those distant galaxies were different from the extrapolation made on the early data! However, they differed in a patterned way, and the simplest way to account for this discrepancy was a variant of Einstein’s “cosmological constant” idea.
Additional support for the Big Bang:
Stephen Hawking calculated that there would have been no way for matter to fly towards a point, “miss” colliding with itself, and fly apart in an apparent expansion without a singularity and Big Bang. (This is somewhere in A Brief History of Time, but Google Books won’t let me find it.)
We can roughly estimate our galaxy’s age by other means (i.e. how much hydrogen has been used up in stars, how much is left). Have you looked into this, to see whether the estimates thus derived are consistent with the estimate of about 10 billion years that the Big Bang theory implies?
ETA: Also, this seems like exactly the sort of issue where the “physicist-test” applies, as described above. For example, being critical of QM on common-sense grounds (of course the electron has to go through one slit or the other!) doesn’t make for discriminating skepticism, since one should assign high probability to physicists having strong evidence to this effect if they’re claiming something weird, or else one should have strong evidence that common sense usually beats the consensus of the physics community. Needless to say, I wouldn’t hold my breath on the second claim.
You win. I did not realize that we knew that galaxies have been flying apart for billions and billions of years, as opposed to just right now. If something has been going on for so long, I agree that the simplest explanation is that it has always been going on, and this is precisely the conclusion which I thought popular science books took for granted.
Your other arguments only hammer the nail deeper, of course. But I notice that they have a much smaller impact on my unofficial beliefs, even thought they should have a bigger impact. I mean, the fact that the expansion has been going on for at least a billion years is a weaker evidence for the Big Bang than the fact that it predicts the cosmic background radiation and the age of the universe.
I take this as an opportunity to improve the art of rationality, by suggesting that in the case where an unofficial belief contradicts an official belief, one should attempt to find what originally caused the unofficial belief to settle in. If this original internal argument can be shown to be bogus, the mind should be less reluctant to give up and align with the official belief.
Of course, I’m forced to generalize from the sole example I’ve noticed so far, so for the time being, please take this suggestion with a grain of salt.
I prefer the meme where you’ve just won by learning something new; you now know more than most people about the justifications for Big Bang cosmology, in addition to (going meta) the sort of standards for evidence in physics, and (most meta and most importantly) how your own mind works when dealing with counterintuitive claims. I won too, because I had to look up (for the first time) some claims I’d taken for granted in order to respond adequately to your critique.
I take this as an opportunity to improve the art of rationality
Good idea! It’s especially helpful, I think, that you’re writing out your reactions and your analysis of how it feels to update on new evidence. We haven’t recorded nearly as much in-the-moment data as we ought on what it’s like to change one’s mind...
When two people argue, and they both realize who is actually right, without drama or flaring tempers, then everybody wins. Even people down the block who weren’t participating at all, a bit; they don’t know it yet, but their world has become slightly awesomer.
but now I can bump my estimate back up. There is at least one belief which my tribe elevates to the rank of scientific fact, yet which I think is probably wrong: I do not believe in the Big Bang.
I don’t think we can reasonably elevate our estimate of our own rationality by observing that we disagree with the consensus of a respected community.
Second, the background radiation which is said to be leftover stray photons from the big bang. If the background radiation was a prediction of Big Bang theory, then I might have been convinced by this experimental evidence, but in fact the background radiation was discovered by accident. Only afterwards did the proponents of Big Bang theory retrofit it as a prediction of their model.
I am wary of this kind of argument. I should not be able to discredit a theory by the act of collecting all possible evidence and publishing before they have a chance to think things through.
I don’t think we can reasonably elevate our estimate of our own rationality by observing that we disagree with the consensus of a respected community.
But isn’t Eliezer suggesting, in this very post, that we should use uncommon justified beliefs as an indicator that people are actually thinking for themselves as opposed to copying the beliefs of the community? I would assume that the standards we use to judge others should also apply when judging ourselves.
On the other hand, what you’re saying sounds reasonable too. After all, crackpots also disagree with the consensus of a respected community.
The point is that there could be many reasons why a person would disagree with a respected community, one of which is that the person is actually being rational and that the community is wrong. Or, as seems to be the case here, that the person is actually being rational but hasn’t yet encountered all the evidence which the community has. In any case, given the fact that I’m here, following a website dedicated to the art of rationality, I think that in this case rationality is quite a likely cause for my disagreement.
I should not be able to discredit a theory by the act of collecting all possible evidence and publishing before they have a chance to think things through.
I agree that if a piece of evidence is published before it is predicted, this is not evidence against the theory, but it does weaken the prediction considerably. Therefore, please don’t publish this entire collection of all possible evidence, as it will make it much harder afterwards to distinguish between theories!
“But isn’t Eliezer suggesting, in this very post, that we should use uncommon justified beliefs as an indicator that people are actually thinking for themselves as opposed to copying the beliefs of the community? I would assume that the standards we use to judge others should also apply when judging ourselves.
On the other hand, what you’re saying sounds reasonable too. After all, crackpots also disagree with the consensus of a respected community.”
Eliezer didn’t say that we should use “disagreeing with the consensus of a respected community” as an indicator of rationality. He said that we should use disagreeing with the consensus of one’s own community as an indicator of rationality.
If the background radiation was a prediction of Big Bang theory, then I might have been convinced by this experimental evidence, but in fact the background radiation was discovered by accident. Only afterwards did the proponents of Big Bang theory retrofit it as a prediction of their model.
Not true; Alpher & Gamow predicted the radiation, although they were off by a few kelvins.
there is no particular reason to assume that if the stars are moving away from each other right now, then they must always have done so. They could be expanding and contracting in a sort of sine wave, or something more complicated.
True, but this lacks parsimony, & the mechanism by which the “sine wave” (or whatever) could be produced is unknown. The universe is expanding now, implying some force behind the expansion. Gravity is attractive only. Celestial objects almost all have net electric charge as close to 0 as makes no odds, so they do not repel each other. The strong nuclear force is always attractive too. You see what I mean? What could possibly cause the outward oscillation, if not extreme density? It’s not like when stars come close to each other they suddenly feel a repulsion.
I don’t see how you can make sense of this without the Big Bang, except by positing unknown physical forces or something.
Very interesting post though. You seem curious; I’d recommend Jonathan Allday’s book “Quarks, Leptons & the Big Bang” on this subject. It’s reasonably technical, given that it’s not a textbook.
Thanks! I had only heard about the accidental discovery by two Bell employees of an excess measurement which they could not explain, but now that you mention that it was in fact predicted, it’s totally reasonable that the Bell employees simply did not know about the scientific prediction at the moment of their measurement. I should have read Wikipedia.
The probability of predicting something as strange as the background radiation given that the theory on which the prediction is based is fundamentally flawed seems rather low. Accordingly, I should update my belief in the Big Bang substantially. But actually updating on evidence is hard, so I don’t feel convinced yet, even though I know I should. For this reason, I will read the book you recommended, in the hope that its contents will manage to shift my unofficial beliefs too. Thanks again!
I’ve been following Alicorn’s sequence on luminousness, that is, on getting to know ourselves better. I had lowered my estimate of my own rationality when she mentioned that we tend to think too highly of ourselves, but now I can bump my estimate back up. There is at least one belief which my tribe elevates to the rank of scientific fact, yet which I think is probably wrong: I do not believe in the Big Bang.
Of course, I don’t believe the universe was created a few thousand years ago either. I don’t have any plausible alternative hypothesis, I just think that the arguments I have read in the many popular science physics book I have read are inconclusive.
First, these books usually justify the Big Bang theory as follows. Right now, it is an observable fact that stars are currently moving away from each other. Therefore, there was a time in the past where they were much closer. Therefore, there was a time where all the stars in the universe occupied the same point. It is this last “therefore” which I don’t buy: there is no particular reason to assume that if the stars are moving away from each other right now, then they must always have done so. They could be expanding and contracting in a sort of sine wave, or something more complicated.
Second, the background radiation which is said to be leftover stray photons from the big bang. If the background radiation was a prediction of Big Bang theory, then I might have been convinced by this experimental evidence, but in fact the background radiation was discovered by accident. Only afterwards did the proponents of Big Bang theory retrofit it as a prediction of their model.
Third, the acceleration. The discovery that the expansion was accelerating was a surprise to the scientific community. In particular, it was not predicted by Big Bang theory, even though it seems like the kind of thing which an explanatory model of the expansion of the universe should have predicted right away.
Fourth, the inflation phase. This part was added later on, once it had been observed that Big Bang theory did not fit with the observed homogeneousness of the cosmos. To me, this seems like a desperate and ad hod attempt to fix a broken theory.
Now, it could be that all these changes are a progression of refinements, just like Newtonian physics was adjusted to take into account the effects of relativity, and just like the spherical Earth was adjusted to make it an elliptical Earth. But the adjustments which Big Bang theory has suffered seem like they should change the predictions completely, rather than, as in the other cases, increasing the precision of the existing theory.
I am, of course, open to being convinced otherwise. If Big Bang theory really is true, then I wish to believe it is true.
The key is there at the end of your quote. From the first set of observations (of relatively close galaxies), the simplest behavior that explained the observations was that everything was flying apart fast enough to overcome gravity. This predicted that when they had the technology to look at more distant galaxies, these too should be flying away from us, and at certain rates depending on their distance.
When we actually could observe those more distant galaxies, we did in fact see them red-shifted as predicted. This alone should be enough to put the “sine wave” theory in the epistemic category of “because the Dark Lords of the Matrix like red shifts”, because the light left these galaxies at all different times! It would take a vast conspiracy for them all to line up as red-shifted right now, from our perspective.
With strong evidence in hand that the galaxies had been flying apart for billions and billions of years, the scientists then noticed an irregularity: the velocities of those distant galaxies were different from the extrapolation made on the early data! However, they differed in a patterned way, and the simplest way to account for this discrepancy was a variant of Einstein’s “cosmological constant” idea.
Additional support for the Big Bang:
Stephen Hawking calculated that there would have been no way for matter to fly towards a point, “miss” colliding with itself, and fly apart in an apparent expansion without a singularity and Big Bang. (This is somewhere in A Brief History of Time, but Google Books won’t let me find it.)
We can roughly estimate our galaxy’s age by other means (i.e. how much hydrogen has been used up in stars, how much is left). Have you looked into this, to see whether the estimates thus derived are consistent with the estimate of about 10 billion years that the Big Bang theory implies?
Finally, the cosmic background radiation gives us way more than one bit of data; its spectrum is precisely the black-body radiation one expects from a Big Bang.
ETA: Also, this seems like exactly the sort of issue where the “physicist-test” applies, as described above. For example, being critical of QM on common-sense grounds (of course the electron has to go through one slit or the other!) doesn’t make for discriminating skepticism, since one should assign high probability to physicists having strong evidence to this effect if they’re claiming something weird, or else one should have strong evidence that common sense usually beats the consensus of the physics community. Needless to say, I wouldn’t hold my breath on the second claim.
You win. I did not realize that we knew that galaxies have been flying apart for billions and billions of years, as opposed to just right now. If something has been going on for so long, I agree that the simplest explanation is that it has always been going on, and this is precisely the conclusion which I thought popular science books took for granted.
Your other arguments only hammer the nail deeper, of course. But I notice that they have a much smaller impact on my unofficial beliefs, even thought they should have a bigger impact. I mean, the fact that the expansion has been going on for at least a billion years is a weaker evidence for the Big Bang than the fact that it predicts the cosmic background radiation and the age of the universe.
I take this as an opportunity to improve the art of rationality, by suggesting that in the case where an unofficial belief contradicts an official belief, one should attempt to find what originally caused the unofficial belief to settle in. If this original internal argument can be shown to be bogus, the mind should be less reluctant to give up and align with the official belief.
Of course, I’m forced to generalize from the sole example I’ve noticed so far, so for the time being, please take this suggestion with a grain of salt.
I prefer the meme where you’ve just won by learning something new; you now know more than most people about the justifications for Big Bang cosmology, in addition to (going meta) the sort of standards for evidence in physics, and (most meta and most importantly) how your own mind works when dealing with counterintuitive claims. I won too, because I had to look up (for the first time) some claims I’d taken for granted in order to respond adequately to your critique.
Good idea! It’s especially helpful, I think, that you’re writing out your reactions and your analysis of how it feels to update on new evidence. We haven’t recorded nearly as much in-the-moment data as we ought on what it’s like to change one’s mind...
When two people argue, and they both realize who is actually right, without drama or flaring tempers, then everybody wins. Even people down the block who weren’t participating at all, a bit; they don’t know it yet, but their world has become slightly awesomer.
I don’t think we can reasonably elevate our estimate of our own rationality by observing that we disagree with the consensus of a respected community.
I am wary of this kind of argument. I should not be able to discredit a theory by the act of collecting all possible evidence and publishing before they have a chance to think things through.
But isn’t Eliezer suggesting, in this very post, that we should use uncommon justified beliefs as an indicator that people are actually thinking for themselves as opposed to copying the beliefs of the community? I would assume that the standards we use to judge others should also apply when judging ourselves.
On the other hand, what you’re saying sounds reasonable too. After all, crackpots also disagree with the consensus of a respected community.
The point is that there could be many reasons why a person would disagree with a respected community, one of which is that the person is actually being rational and that the community is wrong. Or, as seems to be the case here, that the person is actually being rational but hasn’t yet encountered all the evidence which the community has. In any case, given the fact that I’m here, following a website dedicated to the art of rationality, I think that in this case rationality is quite a likely cause for my disagreement.
I agree that if a piece of evidence is published before it is predicted, this is not evidence against the theory, but it does weaken the prediction considerably. Therefore, please don’t publish this entire collection of all possible evidence, as it will make it much harder afterwards to distinguish between theories!
“But isn’t Eliezer suggesting, in this very post, that we should use uncommon justified beliefs as an indicator that people are actually thinking for themselves as opposed to copying the beliefs of the community? I would assume that the standards we use to judge others should also apply when judging ourselves.
On the other hand, what you’re saying sounds reasonable too. After all, crackpots also disagree with the consensus of a respected community.”
Eliezer didn’t say that we should use “disagreeing with the consensus of a respected community” as an indicator of rationality. He said that we should use disagreeing with the consensus of one’s own community as an indicator of rationality.
Not true; Alpher & Gamow predicted the radiation, although they were off by a few kelvins.
True, but this lacks parsimony, & the mechanism by which the “sine wave” (or whatever) could be produced is unknown. The universe is expanding now, implying some force behind the expansion. Gravity is attractive only. Celestial objects almost all have net electric charge as close to 0 as makes no odds, so they do not repel each other. The strong nuclear force is always attractive too. You see what I mean? What could possibly cause the outward oscillation, if not extreme density? It’s not like when stars come close to each other they suddenly feel a repulsion.
I don’t see how you can make sense of this without the Big Bang, except by positing unknown physical forces or something.
Very interesting post though. You seem curious; I’d recommend Jonathan Allday’s book “Quarks, Leptons & the Big Bang” on this subject. It’s reasonably technical, given that it’s not a textbook.
Thanks! I had only heard about the accidental discovery by two Bell employees of an excess measurement which they could not explain, but now that you mention that it was in fact predicted, it’s totally reasonable that the Bell employees simply did not know about the scientific prediction at the moment of their measurement. I should have read Wikipedia.
The probability of predicting something as strange as the background radiation given that the theory on which the prediction is based is fundamentally flawed seems rather low. Accordingly, I should update my belief in the Big Bang substantially. But actually updating on evidence is hard, so I don’t feel convinced yet, even though I know I should. For this reason, I will read the book you recommended, in the hope that its contents will manage to shift my unofficial beliefs too. Thanks again!