And if you had blinked, its multi-billion-light-year journey would have been in vain.
And it’s also, as best as we can tell, consistent with models that are completely, utterly different from that. In other words, we have no clue.
Oh, I see what you’re getting at. Ignorance fought!
Glad to help
Just as a contrast to the Hubble Deep Field image, there is the Boötes void. In an area that should have about 2000 galaxies, there are 60.
Voyager 1 has passed through the Kuiper belt more or less (the boundary is fuzzy) but the outermost part of the Kuiper belt is less than a thousandth of the way to the Oort cloud. All the hulabaloo last year about Voyager 2 entering interstellar space was because it had crossed the heliopause.
Cool. I’ve wondered about such spots.
We cannot begin to answer the OP’s question quantitatively unless we know the precise dimensions of the fingernail in question.
This person might be able to blot out the entire universe.
Sorry, but this is not in contrast to the Hubble Ultra Deep Field. As your cite tells us, the diameter of the Boötes void is only 330 million ly, or 0.27% the diameter of the observable universe, which is a very small fraction of the depth of the Ultra Deep Field. That means that if someone did an Ultra Deep Field in the middle of that void, it would look about the same as the actual HUDF. The main difference would be somewhat fewer foreground galaxies.
As pointed out upthread, these voids and dense clusters average out when you combine everything out to the edge of the observable universe.
I’m getting confused. Does this square with the known distribution of galaxies which seem to suggest very substantial voids? Or are you saying that Geller et al didn’t look deep enough?
There are voids and concentrations or galaxies. Size-wise they’re 3 or more orders of magnitude smaller than the observable universe. So looking in any direction will mean you’re probably looking through 1000 or more voids and clusters. (Well, OK, as long as you don’t look where there’s some foreground obstruction, such as the Zone of Avoidance.) Anyway the voids and dense clusters will average to about the same number of galaxies in any direction.
You’re right. I should have read the description more carefully.
Well thank you.
Would polar coordinates extended into three dimensions not be the right unit to avoid that problem? You should measure those degrees from the center of the Earth (which would be confusingly called a pole) in radians.
Still doesn’t help, because spherical coordinates still have a pole along the z axis. They’re basically just latitude and longitude, combined with height.
What you can use are r, longitude, and sine of latitude.
Please correct me if this is my ignorance speaking, but if the observer were standing on the surface of the Earth wouldn’t they have only half of the galaxies in the observable universe in their field of vision? The rest would be blocked by the the Earth itself, so any calculation should only take half of the observable galaxies as one of its values, right?
That’s relevant for how many you’d see, but not for how many your thumb would block.
Unfortunately not. Consider a one degree wide strip of a sphere, near the sphere’s north pole. If you naively calculate the area of that strip you’d get 1 degree wide by 360 degrees long - just the same as the area of a strip at the equator. But the strip at the equator has a much bigger area, in units of square feet, square meters or square degrees (or the proper unit, steradians)
not “moving away” exactly, just “getting further away”
It’s more a case of more space appearing inbetween, than it is a case of moveing at speed through existing space.
This is why the universe can be 93 billion light years across, despite starting as a point source only 13.8 billion years ago.
I did not write spherical coordinates, but polar coordinates extended in three dimensions. There is no north pole there.
I insist: you should not take a ring between any two latitudes that will obviously be bigger close to the equator than close to the pole, but the maximum circle, which is always equal, as a reference. Every step should be a 1/nth (n being arbitrarily small) of a radian and should be the same area variation, step by step, close to the equator or close to the pole. In fact, there is no pole in polar coordinates other than the point (0, 0, 0), where the system gets its name from.