Its fundamentally different. Science doesn't ask you to accept unknowns on faith, its provides evidence that there is something we dont yet understand and that evidence has predictive value.
If science operated like religion it would say "We dont know what dark energy is, but you have to accept it or your wrong".
Instead the argument is "Hmm... our current best understanding of the universe is lacking, when we add in these extra variables many of our predictions go from wildly inaccurate to nearly accurate. There must be something going on here we cannot observe, so lets call it "dark"."
Dark energy is "Wow, there's a factor at play here that we dont understand, without it our equations do not predict what we see, with it the equations are very accurate. Additionally we can predict multiple different things with this."
And the most important part, as soon as there is evidence that refutes the Dark Energy/Matter hypothesis scientists will quickly (over a few years, a decade at the most) walk away from it. Versus religious systems take centuries for people to shift their beliefs.
No, that is not how science actually progresses, it is an idealised view of it at best. Thomas Kuhn wrote "The Structure of Scientific Revolutions" back in the 1960s. Plank's principle stated "Science progresses one funeral at a time".
Scientists are also human and will tend to defend existing ideas. In cosmology the arguments over LCDM, dark matter and dark energy have been raging for decades. Dark matter people like to say that the Bullet Cluster is incontrovertible evidence of dark matter; MOND people don't agree and point to other aspects they claim refute dark matter! It's gonna take a long time for it all to shake out.
Not an expert, but isn't your LCDM vs MOND example assymetric? Like different kinds of data supports each model very well, and so reconciliation isn't simple?
Certainly true that the data can be viewed in many different ways. Often the same data is used by both sides!
The funeral thing isn't really a position I strongly hold; it's a pithy comment that points out science is a human endeavor and maybe not quite as objective as it is often presented.
But science as a whole is ultimately a self correcting methodology, even if it might take longer than we would want and doesnt always get it right.
MOND people have become a small minority. In addition to the galaxy cluster observations, MOND doesn’t match the CMB power spectrum, while ΛCDM does, and various very precise measurements within the solar system also contradict MOND. This was different 30-40 years ago, but since then, as evidence has strongly mounted against MOND, a lot of “shaking out” has already taken place.
Well, MOND is not a cosmological theory or relativistic - there are some different versions that attempt that. MOND itself can't be used to match the CMB spectrum.
It has always been a minority position - but it is interesting to see a different perspective. ΛCDM is not without it's own problems. Not least that when new observations contradict it, it just gets tweaked - since we still have no idea what the CDM, if it does exist, actually is. It does not have a great predictive record; it is good at explaining obervations after the fact (the CMB notwithstanding).
I am interested to know what the measurements within the solar system are that you refer to. I had thought this was far too small a scale to prove anything about MOND or CDM.
It does not have a great predictive record; it is good at explaining obervations after the fact (the CMB notwithstanding).
Can you elaborate on what you mean? LCDM hasn't been "tweaked" since \Lambda was established in the 90s (at least, not for large-scale cosmological observations). The current discrepancies are all at the precision level (<10%) rather than a qualitative O(1) difference. An important (but not dispositive) nuance is that LCDM well explains all observations individually; the percent-level tensions arise only between fits to datasets, meaning unknown systematics remain a viable explanation.
The unknown fundamental nature of CDM (as important a problem as it is) seems irrelevant to arguments about LCDM's predictivity (as a cosmological model).
1. LCDM predicted hierarchical formation of large galaxies through aggregation. JWST seems to show this is not what happens (large galaxies at early times). I am sure it can be made to work, but it was not a prediction.
2. Constant Lambda - recent obervations seem to show it may be changing (OK - that is more built into the theory rather than being a prediction).
By the way, I am not saying LCDM is not massively successful. It can clearly be used to explain a lot of things. I am saying that I am not aware of many things it successfully predicted ahead of observations being made.
I am saying that I am not aware of many things it successfully predicted ahead of observations being made.
CDM successfully predicted the CMB features that COBE could measure. LCDM certainly was a known model before supernova data in the 90s first provided evidence for it. CMB data shortly after detected a consistent fraction of \Lambda and have since provided evidence of multiple kinds (structure growth in addition to the original, the distance to the last scattering surface). Distances from baryon acoustic oscillations are another subsequent, independent test that corroborated the LCDM model.
2 and (especially) 1 are to me too speculative to place much weight on. I would also draw analogy to the Standard Model of particle physics: its predictivity and past success are not refuted by any deficiencies beyond the regimes we've been able to probe thusfar. (Of course, in the SM we fully expect those deficiencies.) Just to say that not every failed prediction falsifies a model's success in previously established regimes of energy/scale/dynamics.
By the way, I am not saying LCDM is not massively successful. It can clearly be used to explain a lot of things.
Comments
Its fundamentally different. Science doesn't ask you to accept unknowns on faith, its provides evidence that there is something we dont yet understand and that evidence has predictive value.
If science operated like religion it would say "We dont know what dark energy is, but you have to accept it or your wrong".
Instead the argument is "Hmm... our current best understanding of the universe is lacking, when we add in these extra variables many of our predictions go from wildly inaccurate to nearly accurate. There must be something going on here we cannot observe, so lets call it "dark"."
Dark energy is "Wow, there's a factor at play here that we dont understand, without it our equations do not predict what we see, with it the equations are very accurate. Additionally we can predict multiple different things with this."
And the most important part, as soon as there is evidence that refutes the Dark Energy/Matter hypothesis scientists will quickly (over a few years, a decade at the most) walk away from it. Versus religious systems take centuries for people to shift their beliefs.
No, that is not how science actually progresses, it is an idealised view of it at best. Thomas Kuhn wrote "The Structure of Scientific Revolutions" back in the 1960s. Plank's principle stated "Science progresses one funeral at a time".
Scientists are also human and will tend to defend existing ideas. In cosmology the arguments over LCDM, dark matter and dark energy have been raging for decades. Dark matter people like to say that the Bullet Cluster is incontrovertible evidence of dark matter; MOND people don't agree and point to other aspects they claim refute dark matter! It's gonna take a long time for it all to shake out.
Not an expert, but isn't your LCDM vs MOND example assymetric? Like different kinds of data supports each model very well, and so reconciliation isn't simple?
Moreover, your objection that science progresses one funeral at a time is exaggerated, even if it is real, it's not necessarily all that strong: https://pmc.ncbi.nlm.nih.gov/articles/PMC6814193/
Certainly true that the data can be viewed in many different ways. Often the same data is used by both sides!
The funeral thing isn't really a position I strongly hold; it's a pithy comment that points out science is a human endeavor and maybe not quite as objective as it is often presented.
But science as a whole is ultimately a self correcting methodology, even if it might take longer than we would want and doesnt always get it right.
MOND people have become a small minority. In addition to the galaxy cluster observations, MOND doesn’t match the CMB power spectrum, while ΛCDM does, and various very precise measurements within the solar system also contradict MOND. This was different 30-40 years ago, but since then, as evidence has strongly mounted against MOND, a lot of “shaking out” has already taken place.
Well, MOND is not a cosmological theory or relativistic - there are some different versions that attempt that. MOND itself can't be used to match the CMB spectrum.
It has always been a minority position - but it is interesting to see a different perspective. ΛCDM is not without it's own problems. Not least that when new observations contradict it, it just gets tweaked - since we still have no idea what the CDM, if it does exist, actually is. It does not have a great predictive record; it is good at explaining obervations after the fact (the CMB notwithstanding).
I am interested to know what the measurements within the solar system are that you refer to. I had thought this was far too small a scale to prove anything about MOND or CDM.
Can you elaborate on what you mean? LCDM hasn't been "tweaked" since \Lambda was established in the 90s (at least, not for large-scale cosmological observations). The current discrepancies are all at the precision level (<10%) rather than a qualitative O(1) difference. An important (but not dispositive) nuance is that LCDM well explains all observations individually; the percent-level tensions arise only between fits to datasets, meaning unknown systematics remain a viable explanation.
The unknown fundamental nature of CDM (as important a problem as it is) seems irrelevant to arguments about LCDM's predictivity (as a cosmological model).
A couple of examples:
1. LCDM predicted hierarchical formation of large galaxies through aggregation. JWST seems to show this is not what happens (large galaxies at early times). I am sure it can be made to work, but it was not a prediction.
2. Constant Lambda - recent obervations seem to show it may be changing (OK - that is more built into the theory rather than being a prediction).
By the way, I am not saying LCDM is not massively successful. It can clearly be used to explain a lot of things. I am saying that I am not aware of many things it successfully predicted ahead of observations being made.
CDM successfully predicted the CMB features that COBE could measure. LCDM certainly was a known model before supernova data in the 90s first provided evidence for it. CMB data shortly after detected a consistent fraction of \Lambda and have since provided evidence of multiple kinds (structure growth in addition to the original, the distance to the last scattering surface). Distances from baryon acoustic oscillations are another subsequent, independent test that corroborated the LCDM model.
2 and (especially) 1 are to me too speculative to place much weight on. I would also draw analogy to the Standard Model of particle physics: its predictivity and past success are not refuted by any deficiencies beyond the regimes we've been able to probe thusfar. (Of course, in the SM we fully expect those deficiencies.) Just to say that not every failed prediction falsifies a model's success in previously established regimes of energy/scale/dynamics.
Sure, I didn't think so.