NIRCam: https://www.esa.int/ESA_Multimedia/Images/2024/04/Horsehead_...
MIRI: https://www.esa.int/ESA_Multimedia/Images/2024/04/Horsehead_...
Comparison: https://www.esa.int/ESA_Multimedia/Images/2024/04/Slider_Too...
How tiny are we (Humans, Earth, Solar system)... less than a speck of dust in the Sahara.
I used to look up in space when I was growing up and there wasn't any light pollution to the small town I was growing up in. At some point I think I started suffering from 'cosmic horror'. In later years I would pay attention only to the moon, and that reduced my stress significantly.
Nowadays (like in this bit of news, with photos) when I stick to the small photo in an article, I feel ok. When I see it in full size and I zoom in, and I realize that "sh*t! these 5-10-50 tiny white marks are GALAXIES.. and I have to change topics/tabs to keep the cosmic horror at bay.
I don't travel much but when I go to remote areas star gazing is up there on my list of things to do; watch the stars until you're about to pass out from hypothermia, go back inside, make some tea, enjoy the fireplace, forget about the daily (non) problems, it never gets old
What's more amazing is when you share this fact to most people "did you know each dot here is a GALAXY, not a star!" they go "heh... interesting" and shrug.
For some reason that makes the whole thing even crazier to me
I went to sleep thinking about the unignitable size and age of what's all around us in every direction, but particularly that I had just looked at our own galaxy... a galaxy that has been there for billions of years, has always been there my entire and is there right now and there's only this tiny invisible thin bit of atmosphere separating us from it.
Then I thought about the fact tha our solar system is orbiting it right now, and we're orbiting the sun on an invisible track, and the moon orbits us on its own invisible track too.
That's quite a lot to deal with when you only woke up for a pee in the middle of a night in a camping holiday in Wales.
Watching the zoom-out to picture ultra-massive black holes is surreal.
Number of galaxies in the universe: 200 billion to 2,000 billion
That is correct. The only tenable answer to "where did the Big Bang take place" is "everywhere".
But for now we can't really say if the universe in its entirety has a finite size.
It seems like GWB is a superposition of infinite overlapping waves that would be impossible to single out and "unwind" in order to form a map.
And big bang neutrinos are very weak, which makes them undetectable. My assumption was we'd need a breakthrough in measurement sensitivity but is there more to it?
The size and shape of the observable universe also changes. A moving observer, say someone doing 30% of lightspeed, will see further in one direction than another. Accelerate quickly enough and the "dark" side of your custom observable universe might catch up with you, causing all sorts of havoc.
I uncovered this for myself when asking, "where is that point now?" and discovering it was never a point at all, space is expanding from all points simultaneously.
It’s better to think of the Big Bang as describing a point in time rather than a point in space.
https://www.wolframalpha.com/input?i=plot+%28x%2Cy%29+%3D+%2...
f(x,y) = (c * x, c * y)
f(x,y) = c * (x,y)
f(P) = c * P
What do you mean by that last claim? Any observable region is bigger at later times than it is at earlier times. The reason all points always appear to be moving away from all other points is that that is in fact happening.
What's the significance of claiming that the size of the infinite plane never changes? It's just as true that if you start with the unit interval [0, 1] and let it evolve under the transformation f(x) = tx, the size of the interval will never change -- every interval calculated at any point in time will be in perfect 1:1 correspondence with the original (except at t=0). But this doesn't mean that the measured length of the interval at different times isn't changing; it is.
Our current knowledge is functionally zero in the grand scheme of things.
> We may not know the exact size at the start, but we know it was infinitesimally smaller than it is today. So the size of the initial universe isn't a big factor in the equations about how big it likely is today. Weather it started as a few centimeters across or a few thousand light years across, both are functionally zero compared to the current size.
Most things you're saying are correctly rooted except for what's beyond the observable universe. I'm not sure why the staunch belief that you can confidently claim this. To be clear, you aren't provably wrong - likewise not provably right either.
The replies to you are just fine, they represent a significant portion of the scientific community that says our universe is likely infinitely big and that, possibly, the big bang was infinitely small, yet still, still infinitely large. An infinite expanding into infinite still results not knowing what's out there.
PBS Space time talks about it in terms of "scale factor"[0] instead of absolute diameter.
Still, these are all debatable theories, so your take _could_ be valid, but generally, it points infinitely large.
As has already been pointed out, our best current model of our universe is that it is spatially infinite. That means an infinite number of galaxies.
The finite galaxy numbers that astronomers give are for the observable universe.
> The size and shape of the observable universe also changes.
Not the way you are describing, no. The observable universe does increase in size as time goes on, because there is more time for light to travel so the light we see can come from objects further distant. Its shape, however, does not change.
A good reference is Davis & Lineweaver's 2003 paper:
https://arxiv.org/abs/astro-ph/0310808
> A moving observer, say someone doing 30% of lightspeed, will see further in one direction than another.
I don't know where you're getting this from. What part of the universe you can observe from a given point does not depend on your state of motion.
> Accelerate quickly enough and the "dark" side of your custom observable universe might catch up with you, causing all sorts of havoc.
This is nonsense. The Unruh effect is (a) nothing like what you are describing, and (b) irrelevant to this discussion anyway, since the Unruh effect only applies to objects which have nonzero proper acceleration, which is not the case for any galaxies, stars, or planets in the universe.
The unobserved universe is likely to be many orders of magnitude larger than the observed universe. It is possible that it is unimaginably larger.
Technically, it is possible that the unobserved universe is infinite, however whether that is a credible option depends on individual scientists informed intuitions. We simply have no experimental or theoretical evidence either way at this point.
So there is no estimate of how many galaxies there are in the universe in toto.
And that assumes the observable universe is homogeneous, which it isn't
It is now, but up until a few billion years ago, it wasn't, it was decreasing. Many of the objects we currently see are far enough away that the light we are now seeing from them was emitted while the universe's expansion was still decelerating.
> that assumes the observable universe is homogeneous, which it isn't
No, the models cosmologists use do not assume the universe is homogeneous period. They only assume it is homogeneous on average, on large distance scales (roughly scales larger than the size of the largest galaxy clusters).
My understanding is that, at the largest scales, clusters of galaxies are organized along a series of gravitationally bound filaments, sometimes called the cosmic web.
So they aren't distributed like random noise, but more like a web. I have no reason to think this changes anything about calculating average densities, but it is notable that there's the general density but probably a significantly different density within that structure.
400 billion is the high end.
The images that combine all of the frequencies from Chandra X-rays, Hubble's optical, and now Webb's IR make for some truly fascinating images.
Before you jump to "bonkers" maybe give the people you reply to some credit- I'm an amateur astronomer with facts at his disposal.
As am I, and any time I use an eye piece, it is nothing but b&w for DSOs even for something as bright as Orion's Nebula. The spirit of the conversation is if people can see the true color the way images from large telescopes posted in articles like this. They cannot. You take the reaction from the average person that has only seen processed images after looking through a telescope for the first time, and they will almost always have a bit of disappointment in their voice. I have taken my scope to rooftop bars and let patrons look through at whatever can be seen at the time. I have yet to do this and not meet someone that's never looked through a telescope with their own eyes--which is the point of my effort.
For demonstration, I always attach a DSLR to prime focus and display Live View.
I mean, just look at what you wrote:
> Using a telescope to look at things, one only sees a black and white image.
as anyone who owns a telescope that can point at trees knows, you can definitely "look at things" and see them in colour (assuming you have normal colour vision).
I remember seeing Jupiter in colors when looking at it from the backyard of a friend of mine.
That telescope didn't have a motor and we were constantly chasing Jupiter manually. It stays inside the ocular only for a few seconds, then Earth points us into another direction.