Stars.. seeing them.

[Mescalito]

Does a star get brighter when we see the glimmer or does the atmosphere clear and temporarily reveal the bright nature of the star.

M

[dubtrice]

it gets brighter when we see the glimmer because the atmosphere clears, ithink..

[shelbert008]

it's not because the atmosphere clears, it's because our atmosphere is moving. It's just as the earth moves the light from the stars get refracted and it appears as if it's twinkling.



But did you know that some of the stars that we see at night are already dead? It's just because it takes so long for the light to reach us that we can view as if it's a star whereas it may actually be a supernova.

[verklingen]

^ that's why i don't understand how scientists can use red shift to determine that the universe is expanding at an increasing rate. wouldn't a red shift only indicate that it was expanding at an increasing rate however long ago in the past that the distance between us and the observed object causes our perception of it to shift toward the red? think about it. the universe could slow its expansion (assuming there's enough matter out there to do so) and we wouldn't be able to tell until an incredible amount of time had passed. . . much longer than the current estimated age of our universe when taking into account what distance the light from such a decelerating object must travel to reach us, and compounding that by accounting for the increasing amount of space which continues to expand between us and it. given the principle you've described i don't see how red shift can be used to determine much of anything about the current state of our universe.

[dubtrice]

same here...

[shelbert008]

because they use red shift in part of many other formulas. Most of those formulas are derived from what we know about our own solar system and how it may change. But of course everything that our scientists do are really just educated guesses, there's no way for us to really know if the universe is going to continue expanding at an increasing rate. One thing that we do know though is that nature is unpredictable. And we may have these nice theories and formulas to try and predict the course nature will take, but they're just theories.

[Mafoo]

the light has traveled so far the sometimes the waves dont strike your eye as directly so they appear to twinkle. i think its called chromatic abberation

[msicidron]

it's not because the atmosphere clears, it's because our atmosphere is moving. It's just as the earth moves the light from the stars get refracted and it appears as if it's twinkling.



But did you know that some of the stars that we see at night are already dead? It's just because it takes so long for the light to reach us that we can view as if it's a star whereas it may actually be a supernova.

in fact recently the farthest thing ever seen was seen. it was a gamma ray burst or something that happened 9.2 billion light years from earth, but because of the expansion of the universe it ended up traveling 13.1 billion light years to get here.

[shelbert008]

in fact recently the farthest thing ever seen was seen. it was a gamma ray burst or something that happened 9.2 billion light years from earth, but because of the expansion of the universe it ended up traveling 13.1 billion light years to get here.

Awesome I didn't know that. Man, I love our telescopes lol. Just think, they're going to be even better in the future, think of all the things we can discover then. My mouth waters just thinking about it.

[verklingen]

^ correct. in deep space we observe the past, the distant past. therefor using such observation to infer the present state of our universe is absurd.

[verklingen]

^ i believe it man, but not exactly like that. let me explain.

you understand how physicists consider our universe to be suspended in a 4-d fabric of space-time? like how gravity is explained by the sun creating a dimple in space-time which the planets "roll" around like coins in that funnel-shaped deal they used to have at museums, and same with the moon in respect to earth, etc. so we understand that our planet is placed on the 3-d surface of a 4-d universe, kind of like how you and i stand on the 2-d surface of a 3-d globe. you follow? well, try and think where you would have to be standing on earth to be standing in the center of its surface. there are really only two ways of looking at it: either you can say no place is the center or all places are the center. naturally, you would consider the place where you stand as the center because that is your perception of it. in the same way it is "correct" to say that our earth is at the center of the 3-d surface of our 4-d universe. it's just a matter of perception.

[Mescalito]

It wasn't so much a question.. but an appreciation for perspective of two seemingly opposites simultaneously.

It gets deeper..


a perspective of reality in its totality. its definition.. maybe.


M

[Mescalito]

Don't speak about the sun like that mayn.

M

[al-Mu'akhkhir]

^ correct. in deep space we observe the past, the distant past. therefor using such observation to infer the present state of our universe is absurd.

have you considered a career in rocket-science?

[verklingen]

^ not quite, i was going more for astrophysics way back when

I understand 2d vs 3d and 4d, and perception, but how the sun plays into it is ridiculous.

the sun is just an example. anything with mass imprints space-time, "bending" it in such a way that the movement of nearby objects is influenced. the only reason we perceive gravity as some magical, invisible force is because our perception is constrained to length, width and height, and the fabric bends in some other dimension.

i'm not sure what you think i meant the sun was playing into. my main point was that any point on a plane with a closed curvature can be said to be at the center of that plane, so it's just as true for an earthling to say he is at the center of the universe as it is for any other being, at any planet or point in space, to say he is at the center.

[verklingen]

check this out man it really only sounds complicated with words. there's a nice visual 50 seconds in if you're especially pressed for time:



basically imagine you have a trampoline that you've set a bowling ball on. rolling a golf ball around it exemplifies how the planets "roll" around our sun, or how the moon "rolls" around our earth. but the curvature is of a higher dimension, so it surrounds the object in question. for example our planet curves the surrounding higher-d space toward it in such a way that when we jump we fall straight back to it, according with the inward curvature. it's the same concept as the bowling ball and golf ball, only we can't see what's bending.

[stonerkid]

could someone explain the whole 2d 3d 4d thing ?? i kinda allways thought we lived in 3 dimensions or the 3rd dimension...idk helps!!!!!

[verklingen]

we exist in the 3rd dimension.

einstein was able to explain the movements of large-scale bodies (i.e. the interplay of large-scale forces) by considering the 3 spatial dimensions and time as woven into a kind of fabric which is influenced by mass. new theories however add more dimensions to account for the small-scale forces which rule the interactions of small-scale bodies (electrons, protons, etc) in an attempt to get einstein's theories and quantum mechanics to operate in harmony. any number of spatial dimensions could exist and we'd never be able to perceive them because our perceptions are locked within our particular dimensionality.

read the book flatland.