Five billion years? How do we know the sun has been rising every morning for five billion years? Neither the sun nor the earth was very stable that long ago, and all sorts of changes could have - and did - occurred to make the relationship between the two very different than they are now.
Does this mean that using a shorter time span may lead to greater certainty, and thus increase the odds of tomorrow’s sunrise?
You’ve got it backwards. The shorter our historical experience, the LESS sure we are of the upper bound on failure. Or more accurately, the higher the maximum expected likelihood of sunrise failure.
If we as a society suffered from total 24-hour amnesia we’d only have a sample size of 1 previous sunrise and the upper limit on expected sunrise failure would be 1/3 = 33% chance of no sunrise.
Conversely, the more history we get, the lower the likelihood of no sunrise tomorrow becomes.
Again, this is assuming you only have observations of the sunrise to go on, and no understanding of physics.
From this recent article on mapping the surface temperature of an exoplanet:
Is the chance that that planet’s Sun rises* really many percent? Or is it in fact astronomically small? Really, the largest chance of that planet’s Sun rising comes from potential errors in the observations, not from having only three samples.
Relevant XKCD comic:
Next thing you know you’ll be telling me the moon is upside down.
I’m glad this thread was revived.
Of course, the idea and arguments that perceived reality was/could have been created “yesterday” is an oldie but goodie. Hell our friend Mr Wiki gives an astronomic example right off the bat:
Epistemological solipsists claim that realism requires the question: assuming that there is a universe independent of an agent’s mind and knowable only through the agent’s senses, how is the existence of this independent universe to be scientifically studied? If a person sets up a camera to photograph the moon when they are not looking at it, then at best they determine that there is an image of the moon in the camera when they eventually look at it. Logically, this does not assure that the moon itself (or even the camera) existed at the time the photograph is supposed to have been taken. To establish that it is an image of an independent moon requires many other assumptions that amount to begging the question.
I can do some digging to find records establishing five billion years of sunrise, but it’s going to take me a little time to complete. Seven and a half million years.
Intelligent aliens could show up with starships cloaked by optical metamaterial cloaks (or active emission surfaces) that prevent our telescopes from seeing them. The aliens arrived more than a century ago, which is why we didn’t see their drive flare as they decelerated. They unfurl a huge light blocking device overnight that prevents us from seeing the sun in the morning.
Nothing I said there disagrees with fundamental physics. We are intelligent and evolved naturally, aliens could have. While I can’t think of any reason for aliens to show up, they could have done so. Interstellar travel is probably possible using antimatter fuel - the technical obstacles are immense, but nothing fundamental says it cannot be done. Optical cloaks using various forms of optical devices have been demonstrated, although cloaking a gigantic starship would be difficult. I cannot think of any reasons intelligent aliens would want to hide for a century and then suddenly block out the sun, but if you view possible actions an entity might take over a spectrum of possibilities, this action is possible.
But if the sun has some kind of limits to it’s lifespan (or it’s current configuration), each day brings us closer to some night in the future when it burns out (or skedaddles) or something.
So more experience gives us greater confidence in the sun rising each day. Just when we’re really sure, hydrogen runs out and -poof!- out like a candle!*
*I know it doesn’t work like this, but this is a thought experiment, isn’t it. Just think of your own life. Outside of occasional comas, you yourself have risen every day. Yet as your years advance, you become less certain of arising the next day, rather than more confident of continuation.
Good point. I was making an argument from statistics which essentially treats each sunrise as an independent dice roll: rise or no-rise? What’ll it be today?
In that scenario, the more trials which result in it rising, the more confident we become that it will continue doing so. We just had a whole thread on the statistics behind this; I suspect that thread aroused the OP’s curiosity about the Sun as a related question.
Your approach is quite different. Not saying it’s wrong, just different.
You’re right that if the Sun is known to have an indeterminable but finite lifespan, AND if it’s known that the Sun dies with a “poof” without any discernable warning, then each sunrise tells us we’re getting closer to that eventual inevitable poof
But in the absence of any knowledge about even roughly how long the Sun is expected to last, it doesn’t tell us much. Absent knowledge of the Sun’s lifetime, we don’t know how to decrement the odds of tomorrow being a sunny day too.
Your example of humans lifespans is deeply conditioned by your knowledge that human lives run to at most 120 years, and more likely closer to 80. And that I, and probably you, are well along the way to using up that timespan. But imagine if there was no record of any known human ever having died; we’re all still wandering around just fine.
In that case you’d be a lot less inclined to consider each day as evidence of an ever-shortening and all-too-finite fuse. You’d be more inclined to think that every additional year 'ol Methusaleh keeps walking is more good news for your longevity.
Obviously, when we talk about our actual knowledge of the Sun, we’re also generalizing from what we’ve learned about all the other stars we can observe in the Galaxy. SO even though we only have our one Sun at it’s current age, we have indirect experience of lots of other Sun-like objects at various stages of their lifespans. Which muddies these ontological questions a bunch.