I apologize for my poor explanation. I understand that there are regions in our universe where causality cannot apply due to distance and time limitations.

My intention was not to suggest that there is a single shared "now" across the universe. Rather, I meant that the local "now" we experience is the time period where object interactions and state changes occur.

In hindsight, my use of the phrase "unbroken fabric of causality" may have been misleading. What I intended to convey is that within its sphere of influence, causality remains unbroken and could be considered to have one "now" that bends and conforms to the fabric of space/time in that region. However, beyond a certain distance, causality no longer applies, as even light emitted from our location will never reach those areas. In my mind that place would have its own separate discreet "now" to ours.

That is why I used the quotation marks and "better than", but I can't think of any other better reference point

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"They" cant tell us because nobody knows. Chances are, it'll always be impossible to know. It doesnt matter that much though, whichever answer it is, its gonna be too weird to wrap our heads around. That's already the case with a lot of physics we do somewhat understand.

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One way to see this is to consider the clock paradox. Spaceships A and B are moving about 86% the speed of light relative o each other. Spaceship A look at B and says the clock at B has slowed down by half. Time slows down for moving objects. But B says no, they are not moving, A is moving. So B says the clock that the clock at A is the one that has slowed down by half.

So how do we test who is right? If A goes and parks next to B to prove they are right then B would appear to be right. But if B goes and parks next to A to prove they are right then A would appear to be right. “Now” is not any more universal than up and down.

I think the question there in terms of "absolute" is that the CMB is "special" in the sense of being the most distant observable "object", and thus is kind of "absolute" in the sense that its the most encompassing of all possible frames. I.e. all of the rest of the observable universe is within it. Kinda like a skybox in a video game.

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In simpler terms, time on earth and on Mars will never be in sync. People traveling back and forth will experience time differently as well, relative to their counterparts on Earth or Mars.

It actually varies by species! Penguins, on one extreme, have zero hollow bones, keeping a heavy, marrow-filled skeleton to help with deep diving.

For most other birds, the skeleton is actually quite marrow-rich when they are just hatchlings. As they grow into adulthood, the skeleton gradually becomes pneumatized, with air sacs displacing red marrow in many bones. However, this displacement is not 100%...small spots of marrow persist into adulthood in many bones that researchers would otherwise call "pneumatized" or "hollow".

A few bones tend to escape pneumatization entirely, especially the femur and the tibiotarsus. In most birds these red-marrow-filled leg bones will make up the bulk of blood cell production. Other common red-marrow sites in birds are the radius/ulna in the wing, and certain sections of vertebrae (especially the caudal vertebrae in the tail). Many other bones will retain just a small amount of marrow in some birds, and none in others, so there is variation from species to species...but in general those three sites (fibia/tibiotarsus in legs, radius/ulna in wings, vertebrae in tail) will play a big role in making red blood cells for most birds.

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Causality is the reason for there being different nows since if causality existed irrespective of time then things outside of now, from the perspective of an observer, could causes changes too far away to have actually been caused by the observer if, say, information could propagate faster than light. The reason light speed is what it is is because light speed in a vacuum is the speed of causality.

Your definition doesn't make sense as the period where the causes can be manipulated since, for example, my observation of the light from a distant galaxy is completely unaffected by anything happening in my now since the "now" of the galaxy I'm observing occured billions of years ago from my now. Now is entirely relative. The only way I can see the now of the galaxy I'm looking at would be to go there, and by then the now I want to be part of would have passed.

So, what I described it the opposite of that assertion. No one has to be around to observe difference in time, it is inherent to the fabric of reality.

Also, if a tree falls in the woods and there is no one to hear it, it still makes a sound as sound is the propagation of a fluid compression wave, which occurs regardless of an observer. What it doesn't make is a noise, since noise is the conscious experience constructed by the brain using the stimulus of sound.

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I think of the "now" as a kind of unbroken fabric of causality. Although I guess with the universe expansion and stuff there are places that will float past the horizon where anything connected to our specific causality cannot interact.

Anyways in my mind "now" is more tied to cause and effect than it is strictly a time based measurement. As in "now" is simply the period where the "cause" side of cause and effect can be manipulated.

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That's cool it seems way more complex and diverse than I thought. I thought all bones were calcium like matrices with small differences but turns out birds have some other composite

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Bingo! This is effectively the same thing.

However, I have to be a bit pedantic here, in your example the dice might always have been "destined" to be the same, becauase a simple explanation could be that I glued the dice to the bottom of the can, both facing the number 3 up, and that you and a friend measure the same thing because the dice were always going to show 3. This is what we'd call a 'hidden variable theory' and is almost surely not how quantum probability works.

But yeah, entanglement simply means that knowing the outcome of 1 of the experiments gives you some sort of knowledge about the other experiment (like I said, this could be knowing the exact outcome of the other, or just give you better odds than pure luck for guessing the other experiment). The key concept is that you can't control the outcome of the experiments, you just improve your chances of guessing the other experiment correctly, which is exactly what happens in your dice example.

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So if a tree falls and there is noone to hear, it doesn't make a sound.

Short answer: Yes.Long answer: Galvanic corrosion takes place when any two metals come in contact with each other. The severity depends on how cathodic/anodic they are in relation to each other. How aggressive the reaction is depends on how different their electrochemistry is, with the more anodic metal losing material or corroding.Steel is also a very broad category. Where a low alloy steel might corrode in contact with aluminum bronze, a bimetallic couple with stainless steel would cause the aluminum bronze to corrode.
Search for "galvanic series" charts to see where your materials end up to get a general idea of how they would react