I remembered the age of the universe as as 13.7 billion years, but I wasn't sure why that was.
Well, the initial WMAP results in 2003 supported an age of 13.7 billion years. Later results nudged this upwards to 13.8 billion years. Of course, all the results have error bars.
Not to mention the underlying philosophical assumptions, such that the "rate of time" has been constant across all of... time.
Aka: How do we know a "year" 13 Billion "years" ago bears any resemblance to one now? What would it mean for it not to?
If a computer chugs along doing { counter++; } at 1 clock cycle per clock cycle for 13.7 billion clock cycles, it will think 13.7 billion clock cycles have passed when counter is 13.7 billion.
On the other hand, if a computer chugs along at one clock cycle per clock cycle for 1 clock cycle, and reads &counter and sees 13.7 billion, it will think 13.7 billion clock cycles have passed.
Either way it's perfectly capable of introspecting it's source code and logically stepping back until the memory location was 0 to see how many clock cycles would have been required to reach it's current state, but that sort of reasoning is completely devoid of meaning without both perfect knowledge of what the true start state was, and a guarantee that no external influences have occurred.
Here in reality, we know neither the our start state nor our isolation level, but the hubris of many is too string to not at least try finding some logical step-back functions and iterating them until they don't know how to go any further, then proudly proclaiming that "The Start". (after all - how could it not be The Start, look, I can iterate the inverse of my step-backward function from then to now and it matches! QED!)
To exist in the state you describe - with neither start state nor isolation level measurable in any tamper-proof way - and to yet still dedicate one's life to observing and pondering the complexity of the resulting cosmos is, to my eye, laudable and beautiful.
Where you see hubris, I see humility. Everyone who attempts to expand the corpus of human understanding of cosmology knows that the endgame is somewhere short of perfection. And yet they are inspired to carry on. It seems to me that matters of state, economics, medicine, technology, and many other fields will benefit from a similar disposition.
For a hypothetical entity inside the game, nothing would have changed.
https://www.vogonswiki.com/index.php/List_of_CPU_speed_sensi...
We measure time in vibrations of a cesium isotope IIRC
The laws of physics invariance under time is a core to our understanding. It would be very disrupting if we found otherwise.
https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...
It's great to know that say dating using carbon-14 decay is still useful over those time ranges on planet earth (I don't know if that is something we care about given that fossils don't tend to contain much carbon, but coal and oil deposits are around 400 million years old).
I don't want to imply that this is too small of a sample size, but I will imply that nuclear decay, and the movement of galaxies across the universe might be unrelated. Don't know. Not sure how we'd measure that. Supernova observations would tell us about nuclear fusion and it's limits. Does it tell us about nuclear fission? I don't know.
Let's say I walk into a room and observe someone writing a tally mark on a chalk board once every second. I count 4x10^17 tally marks. I might assume that 4x10^17 seconds ago that same person entered the room and started tallying. I might even observe for the next 4x10^17 seconds they continue to tally. Heck I might even see a recorder going that when I play back at what I assume to be 1x speed, has chalk scratches at regular intervals for 4x10^17 seconds. I still don't have any actual evidence that they started those 8x10^17 seconds ago.
Certainly you can't 1) have a model where energy is constant 2) believe there is nonzero energy in the universe and 3) dismiss any model where energy can change as bogus out of hand because you believe it should be constant, without counter-proposing how it even got here.
We have that, it's the big bang.
The argument being:
You can't propose physics ever changed, that'd mean energy could have been created at some point!
Energy was created at some point, wouldn't it be nice to know when?
Everything created at the Big Bang exactly as it is now, stop asking questions.
The difficulty is we don't know what happened in the first planck second after the big bang, let alone before the big bang (if that's meaningful).
We haven't unified quantum mechanics and relativity. Hence we can't be certain that singularities exist, or that the universe started off in a singularity.
It's almost an appeal to common sense. (which, admittedly, is often the best argument we have). IMHO there's often a bit of over-confidence among scientists about the universe being 13 billion years old and what happened during the Big Bang, if it just relies on such a common sense argument.
I know it's unscientific to suggest maybe laws of physics are not time invariant across such scales, because until we have a time machine we can't test this theory, but then flipping the argument (that laws of physics are definitely time invariant) is also technically unscientific -- we're basically assuming this without strong evidence.
This goes back to the old debate on the problem of induction in science, (see David Hume, Karl Popper, etc.) and I think it isn't emphasized enough in modern discussions that, perhaps, there's a small chance that these foundational concepts in physics could be invalid.
To the extent that relates to epistemology that would be more like anti-proof I guess? It does not prove that the laws are time invariant, rather it raises the bar to demonstrate that the laws are not time invariant because that means energy need not be conserved. You can not get one without the other without attacking even deeper fundamentals of modern scientific models. So you must either demonstrate the linked claims, which are pretty foundational themselves, or you must overturn basically everything; both of which demand very robust evidence.
This talk about the "rate of time" doesn't make any sense to me. A second takes one second, and always has.
Isn't this like asking whether the length of a metre might have changed over time? Or the mass of a kilogramme? It looks to me like a category error.
The root of the question is whether there exists an external "system clock", and what that would even mean.
I'll ignore your analogy with a CPU, which I don't think is apposite.
Whether there's a 'system clock', a sort of reference clock that can tell you how fast time is passing, so you can calibrate other clocks against it, seems to be the same category error. As far as I can see, either time is all there, all at once; or one second lasts exactly one second. (I've perpetrated the same category error there, because a second doesn't 'last' for some period of time; it just is).
[Edit] That's not very clear. I mean: if you are measuring a distance, you use a calibrated ruler. If you doubt the calibration of your ruler, you might recalibrate for precision. But you don't have a clear idea of what one foot is, it doesn't make any sense to ask whether your one-foot ruler has grown or shrunk; how would you tell if the purported 'fact' is true or false?
And if some fact about the Universe means that it has grown or shrunk, how would you tell? If you can't in principle tell whether a 'fact' is true or false, it follows that the 'fact' isn't a fact, because it has no effect on anything.
See Russells Teapot.
The question is if there's a different sort of thing beyond our idea of time. We have our concept of N caesium oscillations is the base reference for everything, and the duration of all action is derived from it. Could there be more depth to the rate at which things occur than that, especially on cosmic scales? Could other processes, which operate at different base clock levels, be interacting with the universe we observe in ways we don't yet understand? Could those processes have clock levels that vary over history with respect to our caesium definition?
You can claim not, that's its precisely that shallow. But neither of us can provide evidence either way, and your belief is simply much less interesting to me.
What I ignored was an analogy. Not an argument from analogy; and not a question. Just a rhetorical device, which I considered irrelevant, and didn't feel like arguing about.
> the base reference for everything
Caesium oscillations are a proxy for the passage of time. I can imagine a universe in which the rate of Caesium oscillations might vary, or be influenced, making atomic clocks unreliable. I don't know how one might measure the passage of time directly; I suspect it's impossible, and can only be done with proxies.
I don't see why you couldn't have more than one timescale operating and interacting. It's an interesting speculation. But William of Ockham advised against multiplying hypotheses; and I can't see what multiple interacting timescales might explain, that can't be explained without them.