Space and Astronomy in general

Also, as I understand it, the further we are away from the center of the universe, the more of the universe is further than 14 billion light years away.

I am sure someone has estimated how close we are to the center of the universe. I mean, I guess we are 10 billion light years away? More because the universe is expanding faster than the speed of light?

fangblackbone wrote:

Also, as I understand it, the further we are away from the center of the universe, the more of the universe is further than 14 billion light years away.

I am sure someone has estimated how close we are to the center of the universe. I mean, I guess we are 10 billion light years away? More because the universe is expanding faster than the speed of light?

The universe is infinite, therefore it has no center.

Conversely, by definition, we are at the center of the observable universe.

I don't think we have any way of knowing the true center of the universe, or if there even is one. All we can know is the center of the observable universe, which I'm sorry to say, Galileo, is Earth. Specifically it's me.

Edit: what Jon said. But it's still me.

The universe is infinite, therefore it has no center.

I thought there is a spot for the big bang that would be considered the center of the universe.
If there is no center, then how do we know how old the universe is?

fangblackbone wrote:
The universe is infinite, therefore it has no center.

I thought there is a spot for the big bang that would be considered the center of the universe.
If there is no center, then how do we know how old the universe is?

The best way to think about the big bang is that it happened everywhere at once, rather than at some central point (center of what, after all?)

We can estimate based on how far away the CMB is, since the CMB would be equally far away from any other point in the universe.

fangblackbone wrote:
The universe is infinite, therefore it has no center.

I thought there is a spot for the big bang that would be considered the center of the universe.
If there is no center, then how do we know how old the universe is?

The Big Bang was everywhere, because all of space previously existed in a tiny, tiny region. When the Universe expands, it is not expanding away from a specific point in space. Space is expanding everywhere. ALL of space is expanding away from every other part, being stretched apart. So, there need not be a geometric center of the Universe and there is definitely not a point from which the universe is expanding (at least not in space…in time, sure).

Hmm, so hypothetically a galaxy could be moving towards our galaxy but since the universe is expanding faster, that galaxy will never reach us and is actually getting farther away?

I thought from Cosmos that while the universe grew (if that is even a proper word for it) to like 90% of its size in billionths of a second, it was a "point" before that? I guess it was a "nothing" before that?

fangblackbone wrote:

Hmm, so hypothetically a galaxy could be moving towards our galaxy but since the universe is expanding faster, that galaxy will never reach us and is actually getting farther away?

Invalid hypothesis - if I'm on a 747 flying directly away from you at 500 knots, but I'm running down the length of the airplane from the cockpit to the tail (i.e. "moving towards you") at 10 knots, I'm not moving towards you.

fangblackbone wrote:

Hmm, so hypothetically a galaxy could be moving towards our galaxy but since the universe is expanding faster, that galaxy will never reach us and is actually getting farther away?

correct! Like it's swimming upstream toward us but the river is flowing faster than it can swim.

I thought from Cosmos that while the universe grew (if that is even a proper word for it) to like 90% of its size in billionths of a second, it was a "point" before that? I guess it was a "nothing" before that?

Obviously we can't know for sure what it was like before inflation happened, but let's say it was a point. That point contained literally everything, including space itself. The expansion of this point gets very tricky to conceptualize because it's expanding in 3 dimensions, rather than 2. The typical analogy is that of a balloon being inflated and how its skin expands without any increase in mass. That happens in two dimensions, so now try to imagine the "skin" of the universe expanding in 3 (I can't).

Chairman_Mao wrote:

I don't think we have any way of knowing the true center of the universe, or if there even is one. All we can know is the center of the observable universe, which I'm sorry to say, Galileo, is Earth. Specifically it's me.

Edit: what Jon said. But it's still me.

Yours is you. Mine is me. Technically every point in existence is the center of its own observable universe.

Loving this discussion!

A good article about Webb’s leadership during the “Lavender Scare,” when LGBTQ federal workers were expunged from the State Dept. and NASA. There’s and even better Twitter thread by the author.

@adamspacemann wrote:

"That Webb played a leadership position in the Lavender Scare is undeniable," they write. And then again later, just in case we didn't get the point: "I
have not been able to find any credible sources that dispute that Webb played a leadership role in the Lavender Scare....

"To the contrary, the rigorous, scholarly, and peer-reviewed materials about that time--including archival records--quite explicitly situate Webb as playing a leadership role in the Lavender Scare firings as early as 1950."

@adamspacemann wrote:

This same person goes on to explain exactly why keeping Webb's name on the telescope is harmful "The name of such a facility will be bound to hundreds, if not thousands of people’s careers. The name will be tied to their data, their findings papers, and their press releases."…..

Furthermore, much like there are NASA Hubble fellows and Spitzer fellows, one day there's going to be Webb fellows. Can you imagine a queer astronomer being totally happy and joyful to receive a fellowship with the name of somebody who worked to exclude people like them?

The whole argument that “Webb was a man of his day” is completely destroyed by these last comments and this one from astronomer Scott Gaudi:

Scott Gaudi wrote:

"We’re naming a telescope for people now, and we should be following the morals that we believe in now."

Webb Telescope’s Coldest Instrument Reaches Operating Temperature

MIRI is now below 7 Kelvin. Time to finish up some calibration and get to the science.

7K... What is ambient out there?

Robear wrote:

7K... What is ambient out there?

No such thing as ambient in vacuum.

The effective ambient temperature in space (if you shield off all sunlight) is the temperature of the cosmic background radiation, 2.78 K. This is the temperature an inert body would reach in equilibrium, if there are no other internal or external sources of energy.

In practise there are a couple of caveats here: first, starlight would raise the equilibrium temperature a little, but I'm not sure how much; probably a small fraction of a degree. Second, the JWST's sun shield won't be absolutely 100% perfectly effective at cutting off all incoming energy; I think this probably accounts for most of the difference between the 7 K operating temperature and the background temperature.

At first I read that as -7K and my mind almost blew a gasket

Jonman wrote:

No such thing as ambient in vacuum.

What does this mean in practice?

Chairman_Mao wrote:

At first I read that as -7K and my mind almost blew a gasket

That's probably the current temperature up in Winnipeg.

If anyone can manage to get below Absolute Zero it's those guys.

Robear wrote:
Jonman wrote:

No such thing as ambient in vacuum.

What does this mean in practice?

Ambient temperature is the temperature of the surrounding medium. E.g the temperature of the air in the room you're in.

There's no surrounding medium in space to reference the temperature of.

Alternative answer - it means I'm a pedantic snot

I didn't think space was an absolute vacuum...

slashpedant++

"Touched down" lol

\

Now, all we have to do is find the rest of the Millenium Falcon.

I think the most amazing thing to me about pictures like that is when you transpose yourself in that spot and humbly realize you are on another planet.

It may be debris, rock and dirt but it is alien debris, rock and dirt...

Robear wrote:

"Touched down" lol

That was totally unintentional I assure you.

Also:
NASA’s Webb In Full Focus, Ready for Instrument Commissioning

NSMike wrote:

Sagittarius A, baby.

That's one impressive A*Hole.

Wow!
That zoom in animation is awe inspiring. An awesome A*hole I guess!