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Cake day: June 4th, 2023

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  • Tlaloc_Temporal@lemmy.catoScience Memes@mander.xyzRaisins!!
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    4 minutes ago

    Yes, relatively means that light appears to move at c in every inertial reference frame. That doesn’t change how we measure distance in a single reference frame.

    How can a metre bar be measured as a metre when it’s one unit and two units long? We’re measuring the bar in it’s own reference frame each time, so relatively causes no change. Either c increased, or time slowed down to match the expansion of space. Either way, light doesn’t get redshifted by expansion.

    Help me understand, how does light appear to change speed over time in the same reference frame? How do we see a change of distance affect light between galaxies, but not between atoms?


  • Tlaloc_Temporal@lemmy.catoScience Memes@mander.xyzRaisins!!
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    2 hours ago

    I am aware of what redshift is. What I don’t understand is how you think a metre bar can expand and the speed of light increase in lockstep with it such than we can’t measure the change.

    Let’s say we have a metre bar that’s currently one unit long, and we measure it to be one metre long. There’s also a galaxy a billion light years away.

    Let’s say the universe doubles in size after a billion years. The metre bar is two units long, but we still measure it to be one metre long, because the speed of light has doubled (presumably). We measure the light as the same length. The light from the galaxy has now reached us, and is twice as long, but is also moving twice as fast, so the wavelength stays the same. We measure the light as the same length.

    Do you see my issue with this situation? How can the measured length of light change (redshift) while the measured length of light also stay the same (metre bar)?

    Either redshift isn’t caused by expansion, the fundamental forces and constants are changing as we expand, or space is expanding but matter isn’t. We have good corroborating evidence that redshift is caused primarily by expansion. We also have evidence that the laws of physics haven’t changed significantly in at least the last 2 billion years or across the universe. And lastly, we can measure the acceleration of expansion by several corroborating methods, including redshift.

    I’d love to be proven wrong here, the implications of gluons being streched by expansion is fascinating.


  • Tlaloc_Temporal@lemmy.catoScience Memes@mander.xyzRaisins!!
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    4 hours ago

    What is expanding in this scenario? If atoms are expanding, then either atomic forces have also scaled to match the expansion, or atoms are getting more radioactive?

    I don’t understand how atoms are supposed to be expanding in this model. The size of atomic nuclei and electron clouds are governed by the strength and range of the fundamental forces. If everything was expanding in lockstep such that atoms expand but don’t change their properties, then there would be no observable effects. Yet we can see the distance between galaxies not just getting larger, but speeding up.

    If orbits, matter, and even the fundamental forces were expanding to match, no such change in “distance” should be possible, beyond the normal movement of matter.

    If our metre stick was measured as 1/299,792,458th of a light second, then a million years later it was measured as exactly the same length but was somehow dimensionally larger, then lightseconds must have become larger is lockstep.

    If that were true, this expansion could not explain the redshifting of light, as c would increase in lockstep with space, leaving light the same wavelength. Redshifting only happens when the distance between waves increases in relation to the speed of light, and so a universe with redshifting must have a difference in the rate of expansion and the rate of c scaling. Such a difference should be visible as increasing distance or an increase in the flow of time, at minimum.

    In your model, everything is expanding equally. Literally everything, including the speed of light, the elementary charge, and even the plank constant, are expanding in lockstep, to the point of unobservability. Is this right?


  • Tlaloc_Temporal@lemmy.catoScience Memes@mander.xyzRaisins!!
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    9 hours ago

    Yes, all distances are expanding, but not everything in space is expanding. Atoms aren’t expanding because atomic forces are far stronger than expansion is, for example.

    Yet the distance between galaxies is increasing, so there must be a crossover point where one structure can stay structured but a slightly bigger structure is torn apart.

    My question was if this size is larger or smaller than galaxies, and it seems to be quite a bit larger than galaxies at the moment.

    The interesting thing is that the expansion is increasing, so this size limit is shrinking. Unless some change in forses happens (like inflation or some kind of false vacuum collapse) the limit will eventually be smaller than galaxies and they’ll get ripped apart. Eventually star systems will be ripped apart too, then stars (if any remain at that point) then planets, molecules, atoms, and bosons; and if if that continues to quarks funny things start happening that kind of look like the big bang.

    That last part is still speculation of course, but I do still wonder if the expansion of the universe affects galaxy formation and dynamics, and if ancient galaxies were different in part because of this.



  • At the planetary scale, such a change would be completely overpowered by other orbit defining effects, like resonance, mass flow/loss, and even drag.

    At the cluster scale, I can absolutely see spacetime expansion overpowering gravity.

    At the galaxy level, I can’t tell. Does spacetime expansion limit the size of galaxies? Is that limit shrinking due to the acceleration of expansion? Are galaxies under that limit larger than otherwise expected? Is this effect large enough to effect the speed of galaxy rotation and does it need to be taken into accout when measuring the effects of dark matter?










  • There’s a difference between sharing information and a river of glorification.

    Not all the WWII history shows glorified it, but lots of them did and did often. I’ve heard too much about the brilliant tactical minds that ensured the fall of Nazi Germany and paved the way for democracy and freedom. Too many tank battles are called great, and not enough called tragic. Famines and desyruction of infrastructure ate often mentioned for their strategic effects, and rarely for the rapid destruction of society they cause.






  • Tlaloc_Temporal@lemmy.catoScience Memes@mander.xyzOxygen
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    13 days ago

    Fire gets it’s energy from fuel+oxygen. Most life does too. Plants (and other photosynthetic organisms) can also get energy from light but that requires you to sit in the sun doing not much for a long time. There’s also chemosynthesis, where energy is obtained from a chemical reaction, but that’s usually not nearly as powerful as oxidation.

    Put another way, a car with NOS is way faster and more powerful than one without. So too is life that uses oxygen more powerful than life that doesn’t.