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Matter in other galaxies would behave differently from matter in the Milky Way if fundamental constants are not always true. I argue about this sometimes. Other

by 1970-01-01 2y ago

Matter in other galaxies would behave differently from matter in the Milky Way if fundamental constants are not always true. I argue about this sometimes. Others keep stating that the wavelengths are equal, so everything else must be.

gmueckl 2y ago
I think the better way to ask this question is: how much large scale spatial variation can there be in the laws of physics so that the observable behavior doesn't contradict existing observations? As far as I remember, this has been studied, but I can't find a reference right now.
- canadianfella 2y ago
  [dead]
- jepler 2y ago
  wikipedia has a high level review of current constraints: https://en.wikipedia.org/wiki/Time-variation_of_fundamental_constants https://en.wikipedia.org/wiki/Time-variation_of_fundamental_... fine-structure constant: less than 10^−17 per year gravitational constant: less than 10^−10 per year proton-electron mass ratio: less than 10^−16 per year
rkagerer 2y ago
What's meant by "the wavelengths are equal"? (And have we measured comparable wavelengths in other galaxies?)
- fnordpiglet 2y ago
  Presumably they mean propagating EM radiation we observe from earth appears to behave the same on earth as we observe from distant galaxies since the event that created them happened at a time much different than ours and a distant region of space.
  - saalweachter 2y ago
    I mean, technically the EM radiation we observe from distant galaxies does look different than the EM radiation we observe locally: it's red-shifted. I'm sure someone has proposed this is due to physical constants changing over time, rather than the expansion of space-time, and I'm sure someone else has explained why this is wrong.
- itishappy 2y ago
  The wavelengths of physical processes are equal. If fundamental constants changed, we'd expect, say, the Lyman series to change too.
- analog31 2y ago
  Yes, we've measured comparable wavelengths. It's one way we can measure the red shift. Not just (red shifted) absolute wavelengths, but the relative spacing between them are quite sensitive to physical constants. These spectra can also be used for identifying the elemental composition of stars.
- cryptonector 2y ago
  > What's meant by "the wavelengths are equal"? Absorption lines of the elements in the stars whose starlight we observe. THey are the same after correction for redshift.
mysecretaccount 2y ago
If the fundamental constants are not constant, why not expect them to change in this galaxy as well? The appeal to "other galaxies" seems suspect to me, a way to evade falsifiability.
- itishappy 2y ago
  "A way to evade falsifiability" is the goal of the statement, given that we've been searching for evidence to the contrary for as long as we've been able. We haven't found any, and we've searched close-at-hand the most thoroughly.
- 1970-01-01 2y ago
  The idea is they're fixed/set by the overall size of the galaxy.
- mbrubeck 2y ago
  If the constants change over very long time spans, we could observe this by looking at distant galaxies from billions of years ago. We don’t have a way to make similar observations within our own galaxy.
  - lupusreal 2y ago
    What if the constants only changed over incredibly small scales, vibrating back and forth between two very similar numbers like a standing wave with extremely small amplitude and wavelength, such that any measurement done on even small scales has trouble seeing anything but the average?
    - raattgift 2y ago
      Let's start with the universe since the ignition of the first stars. Your question is also super-interesting in the context of the very early universe, so I'll come back to that further below. Depending on the constants, with significant fluctuation of them you'd expect spectral line broadening rather than the sharp lines we see in precision interferometry, violations of local Lorentz invariance, different structures in "stacked" spectra (like the Lyman-alpha forest), and instabilities in Keplerian orbits. Present measurement precision of subatomic transition spectra has really boxed you in on this: many physical constants have relative standard uncertainties on the order of 10^-10 or better. > any measurement ... [sees only] the average So you'd start wondering: in the limit of infinitesimal fluctuations, is a fluctuating constant just constant rather than an "effective constant"? Where's there's still wiggle room is in the exact masses of heaver generation standard model particles (top quark, tau mass, W-to-Z mass ratio for example) and somewhat frustratingly Newton's gravitational constant, all of which have relative standard uncertainties worse than 10^-5. (There's a quick explanation of standard uncertainty and relative standard uncertainty at <https://www.physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html https://www.physics.nist.gov/cgi-bin/cuu/Info/Constants/defi...>) However, assuming cosmic inflation, one might expect incredibly small scale fluctuations in physical constants to be stretched, just like incredibly small scale fluctuations in the densities of matter and radiation. This could lead to later-universe regions of arbitrary size with a significantly different value for one or more physical constants, just like we see regions relatively stuffed with galaxies (filaments) and regions that are relatively empty (supervoids). We'd expect that when we look at different parts of the sky we'd see differences in things like the Lyman-alpha forest, the population and/or spectra and/or light curves of quasars/supernovae/variables, and so on. So, in order to have the apparently constant physical constants we observe, while keeping your idea that there are tiny fluctuations in them, you'd have to suppress high frequency fluctuations in the constants in the very early universe, because otherwise you'd have to suppress gross effects like different gas and dust chemistry when comparing one galaxy cluster to another. And we are looking: https://cen.acs.org/physical-chemistry/astrochemistry/Scientists-find-complex-organic-molecules-young-galaxy-12-billion-light-years-away/101/web/2023/06 https://cen.acs.org/physical-chemistry/astrochemistry/Scient... (The cosmic inflation epoch predates the "freezing-out" of some of the physical constants, so my thinking is that during inflation there must be some precursor constant(s) that determine(s) the mass of the electron (for example) once there are electrons after the electroweak epoch. Even after inflation the ordinary expansion of the universe can stretch fluctuations enough that (assuming your idea) there is likely to be a directional dependence on precision extragalactic astronomy.)
renewiltord 2y ago
One thing I have been arguing for a long time is that the fundamental constants are different until we observe them. i.e. if we don't observe it, it's possible for a tennis ball to travel through a wall. But in the universal program, if we will now or later observe the result, then it won't happen. But it'll happen so long as we will never observe the result. In fact, it's probably happened many times. No one has proven that this is impossible, AFAIK.
- ezrast 2y ago
  What does "impossible" mean to you if not that a thing and it's consequences can never be observed?
  - renewiltord 2y ago
    Impossible means it does not happen, not that it does not happen only when we look. Just because we can't see it doesn't mean that it doesn't happen. After all, as the comment I replied to pointed out, other galaxies can have different constants. We have to be humble and admit we just don't know.
    - jiggawatts 2y ago
      The problem with these type of arguments is rigorously defining “we” and “look”. Turns out that our gaze has no effect on anything and we’re uninteresting squishy bags of mostly water as far as physical processes are concerned.
      - renewiltord 2y ago
        Yeah, but no one has proven that this is impossible so it's still possible. Just like OP comment.
        wizzwizz4 2y ago
        https://www.smbc-comics.com/comic/2014-03-25 https://www.smbc-comics.com/comic/2014-03-25
gitaarik 2y ago
Well, if you think about it, on a large scale of the universe, our laws are helped by our mathematical inventions of dark matter and dark energy. So is there really dark matter and dark energy, or is our understanding of the laws of the universe incomplete?
- thewarpaint 2y ago
  > So is there really dark matter and dark energy, or is our understanding of the laws of the universe incomplete? These propositions are not mutually exclusive, the former implies the latter, right?
- foxyv 2y ago
  As I understand it, dark matter and dark energy are just placeholders for discrepancies between our current physical model and observations made by telescopes like Hubble and Kepler. This could mean either that our measurements are inaccurate, or that the model is incomplete. Honestly, I think that both are extremely likely.
  - AlexAndScripts 2y ago
    Dark matter (matter that has mass but does not interact in any other way) might be the literal solution. But there are also other suggestions (MOND is a big one). The https://en.m.wikipedia.org/wiki/Bullet_Cluster https://en.m.wikipedia.org/wiki/Bullet_Cluster is pretty interesting.
  - BurningFrog 2y ago
    "Dark matter" and "dark energy" could just as well be called "unexplained matter" and "unexplained energy". These terms are mostly placeholders for things we don't understand.
    - cowl 2y ago
      not even that. "unexplained matter" implies that there is some matter to explain (what type etc) when in reality is an unexplained observation that could be explained by current laws/constants if only there was some more (actually a lot more) matter. is a pure mathematical construct and mathematically it wold be just as valid to ad "dark constant modifier"
cryptonector 2y ago
Not necessarily. We have redshift and we use that to measure distance (in space and time). If fundamental constants were different in the past that might merely change only what distances we measure.
- analog31 2y ago
  That would probably require quite a coincidence, since the redshift and the spacing between wavelengths both depend on the same constants but in different ways.

gmueckl 2y ago

I think the better way to ask this question is: how much large scale spatial variation can there be in the laws of physics so that the observable behavior doesn't contradict existing observations? As far as I remember, this has been studied, but I can't find a reference right now.

canadianfella 2y ago
[dead]
jepler 2y ago
wikipedia has a high level review of current constraints: https://en.wikipedia.org/wiki/Time-variation_of_fundamental_constants https://en.wikipedia.org/wiki/Time-variation_of_fundamental_... fine-structure constant: less than 10^−17 per year gravitational constant: less than 10^−10 per year proton-electron mass ratio: less than 10^−16 per year

rkagerer 2y ago

What's meant by "the wavelengths are equal"? (And have we measured comparable wavelengths in other galaxies?)

fnordpiglet 2y ago
Presumably they mean propagating EM radiation we observe from earth appears to behave the same on earth as we observe from distant galaxies since the event that created them happened at a time much different than ours and a distant region of space.
- saalweachter 2y ago
  I mean, technically the EM radiation we observe from distant galaxies does look different than the EM radiation we observe locally: it's red-shifted. I'm sure someone has proposed this is due to physical constants changing over time, rather than the expansion of space-time, and I'm sure someone else has explained why this is wrong.
itishappy 2y ago
The wavelengths of physical processes are equal. If fundamental constants changed, we'd expect, say, the Lyman series to change too.
analog31 2y ago
Yes, we've measured comparable wavelengths. It's one way we can measure the red shift. Not just (red shifted) absolute wavelengths, but the relative spacing between them are quite sensitive to physical constants. These spectra can also be used for identifying the elemental composition of stars.
cryptonector 2y ago
> What's meant by "the wavelengths are equal"? Absorption lines of the elements in the stars whose starlight we observe. THey are the same after correction for redshift.

mysecretaccount 2y ago

If the fundamental constants are not constant, why not expect them to change in this galaxy as well? The appeal to "other galaxies" seems suspect to me, a way to evade falsifiability.

itishappy 2y ago
"A way to evade falsifiability" is the goal of the statement, given that we've been searching for evidence to the contrary for as long as we've been able. We haven't found any, and we've searched close-at-hand the most thoroughly.
1970-01-01 2y ago
The idea is they're fixed/set by the overall size of the galaxy.
mbrubeck 2y ago
If the constants change over very long time spans, we could observe this by looking at distant galaxies from billions of years ago. We don’t have a way to make similar observations within our own galaxy.
- lupusreal 2y ago
  What if the constants only changed over incredibly small scales, vibrating back and forth between two very similar numbers like a standing wave with extremely small amplitude and wavelength, such that any measurement done on even small scales has trouble seeing anything but the average?
  - raattgift 2y ago
    Let's start with the universe since the ignition of the first stars. Your question is also super-interesting in the context of the very early universe, so I'll come back to that further below. Depending on the constants, with significant fluctuation of them you'd expect spectral line broadening rather than the sharp lines we see in precision interferometry, violations of local Lorentz invariance, different structures in "stacked" spectra (like the Lyman-alpha forest), and instabilities in Keplerian orbits. Present measurement precision of subatomic transition spectra has really boxed you in on this: many physical constants have relative standard uncertainties on the order of 10^-10 or better. > any measurement ... [sees only] the average So you'd start wondering: in the limit of infinitesimal fluctuations, is a fluctuating constant just constant rather than an "effective constant"? Where's there's still wiggle room is in the exact masses of heaver generation standard model particles (top quark, tau mass, W-to-Z mass ratio for example) and somewhat frustratingly Newton's gravitational constant, all of which have relative standard uncertainties worse than 10^-5. (There's a quick explanation of standard uncertainty and relative standard uncertainty at <https://www.physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html https://www.physics.nist.gov/cgi-bin/cuu/Info/Constants/defi...>) However, assuming cosmic inflation, one might expect incredibly small scale fluctuations in physical constants to be stretched, just like incredibly small scale fluctuations in the densities of matter and radiation. This could lead to later-universe regions of arbitrary size with a significantly different value for one or more physical constants, just like we see regions relatively stuffed with galaxies (filaments) and regions that are relatively empty (supervoids). We'd expect that when we look at different parts of the sky we'd see differences in things like the Lyman-alpha forest, the population and/or spectra and/or light curves of quasars/supernovae/variables, and so on. So, in order to have the apparently constant physical constants we observe, while keeping your idea that there are tiny fluctuations in them, you'd have to suppress high frequency fluctuations in the constants in the very early universe, because otherwise you'd have to suppress gross effects like different gas and dust chemistry when comparing one galaxy cluster to another. And we are looking: https://cen.acs.org/physical-chemistry/astrochemistry/Scientists-find-complex-organic-molecules-young-galaxy-12-billion-light-years-away/101/web/2023/06 https://cen.acs.org/physical-chemistry/astrochemistry/Scient... (The cosmic inflation epoch predates the "freezing-out" of some of the physical constants, so my thinking is that during inflation there must be some precursor constant(s) that determine(s) the mass of the electron (for example) once there are electrons after the electroweak epoch. Even after inflation the ordinary expansion of the universe can stretch fluctuations enough that (assuming your idea) there is likely to be a directional dependence on precision extragalactic astronomy.)

renewiltord 2y ago

One thing I have been arguing for a long time is that the fundamental constants are different until we observe them. i.e. if we don't observe it, it's possible for a tennis ball to travel through a wall. But in the universal program, if we will now or later observe the result, then it won't happen. But it'll happen so long as we will never observe the result. In fact, it's probably happened many times. No one has proven that this is impossible, AFAIK.

ezrast 2y ago
What does "impossible" mean to you if not that a thing and it's consequences can never be observed?
- renewiltord 2y ago
  Impossible means it does not happen, not that it does not happen only when we look. Just because we can't see it doesn't mean that it doesn't happen. After all, as the comment I replied to pointed out, other galaxies can have different constants. We have to be humble and admit we just don't know.
  - jiggawatts 2y ago
    The problem with these type of arguments is rigorously defining “we” and “look”. Turns out that our gaze has no effect on anything and we’re uninteresting squishy bags of mostly water as far as physical processes are concerned.
    - renewiltord 2y ago
      Yeah, but no one has proven that this is impossible so it's still possible. Just like OP comment.
      - wizzwizz4 2y ago
        https://www.smbc-comics.com/comic/2014-03-25 https://www.smbc-comics.com/comic/2014-03-25

gitaarik 2y ago

Well, if you think about it, on a large scale of the universe, our laws are helped by our mathematical inventions of dark matter and dark energy. So is there really dark matter and dark energy, or is our understanding of the laws of the universe incomplete?

thewarpaint 2y ago
> So is there really dark matter and dark energy, or is our understanding of the laws of the universe incomplete? These propositions are not mutually exclusive, the former implies the latter, right?
foxyv 2y ago
As I understand it, dark matter and dark energy are just placeholders for discrepancies between our current physical model and observations made by telescopes like Hubble and Kepler. This could mean either that our measurements are inaccurate, or that the model is incomplete. Honestly, I think that both are extremely likely.
- AlexAndScripts 2y ago
  Dark matter (matter that has mass but does not interact in any other way) might be the literal solution. But there are also other suggestions (MOND is a big one). The https://en.m.wikipedia.org/wiki/Bullet_Cluster https://en.m.wikipedia.org/wiki/Bullet_Cluster is pretty interesting.
- BurningFrog 2y ago
  "Dark matter" and "dark energy" could just as well be called "unexplained matter" and "unexplained energy". These terms are mostly placeholders for things we don't understand.
  - cowl 2y ago
    not even that. "unexplained matter" implies that there is some matter to explain (what type etc) when in reality is an unexplained observation that could be explained by current laws/constants if only there was some more (actually a lot more) matter. is a pure mathematical construct and mathematically it wold be just as valid to ad "dark constant modifier"

cryptonector 2y ago

Not necessarily. We have redshift and we use that to measure distance (in space and time). If fundamental constants were different in the past that might merely change only what distances we measure.

analog31 2y ago
That would probably require quite a coincidence, since the redshift and the spacing between wavelengths both depend on the same constants but in different ways.