I just lazily took pi/l for l=2500, the largest l that Planck papers plot. Indeed, the ground-based telescopes push to somewhat higher l.

Hmm, around 1 degree (where the fluctuation power peaks), the time scale for the CMB to change would be of order a billion years, or one part in ~10^(9) per year. I wonder how far off that kind of sensitivity is.

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What's 0.07° (4.2 arcmin) based on? It's somewhat close to Planck's FWHM at its highest frequencies (the main CMB frequencies are more like 5-7 arcmin), but Planck isn't the state of the art at small scales - that's the South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) with resolutions of about 1 arcmin.

Though as you say in another comment, there's hardly any CMB left at those scales. ACT has published a foreground-cleaned CMB temperature power spectrum with significant signal detection up to l = 3700 which corresponds to roughly 0.10° = 5.4 arcmin 0.05° = 2.9 arcmin.

I think I read a paper at some point about the feasibility of detecting the time-derivative of the CMB. If I remember correctly, it was actually the largest scales that were considered the most promising there, not the smallest. Those scales change extremely slowly, but the signal is also much brighter there, and from what I remember that won out.

Humidity is the key thing here. Colder air holds less water vapor.

There is an equation that describes visibility and the Western US always has much longer view-lengths than the Eastern US because of the relative water vapor content (and to a lesser extent, sulfates from coal are way way down in the whole US).

Too much detail here, but RH = relative humidity and the other stuff is pollutants in particulate matter in the air.

bext ≈ 3 × f(RH) × [Ammonium Sulfate] + 3 × f(RH) × [Ammonium Nitrate] +

4 × [Organic Mass] + 10 × [Elemental Carbon] + 1 × [Fine Soil] + 0.6 × [Coarse Mass]

+ Rayleigh scattering

Sorry, I typed "reionization" but meant "recombination"... I've fixed that.

To clear things up:

• Recombination is a process that occurred at a time of around 370000 years. At this time, the universe cooled enough that all of the free protons and electrons condensed into neutral hydrogen. Without all of the free electric charges, the universe became transparent. (The "re" in "recombination" is a complete misnomer.)

• Reionization is a process that occurred at a time of around 200 million to 1 billion years. This is what those videos are showing. When the first galaxies formed, the light emitted by their stars and black hole accretion disks ionized essentially all of the neutral hydrogen in the universe. (The universe didn't become opaque again, though, just because the hydrogen was far too sparse by this time.)

I'm by far not an expert. Someone else can probably weigh in more, but in veterinary drug books, they often list the drug and all routes of administrations and efficacy/ effects species, etc. It can get interesting in different species. Not all animals will take a pill.

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Tens of years... Wow, so short. Really puts the temperature uniformity in a new perspective for me.

Are this and this still about right for how we think it would have looked?

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On average, yes, but in reality the recession velocity is neither constant nor linear. Points at the distance of the CMB scattering surface are currently receding from us at more than three times the speed of light.

The Milky Way-Andromeda system is bound together by gravity, and so is unaffected by expansion. Newtonian mechanics is all you need to calculate the time until the two galaxies collide (notwithstanding the uncertainty in the current distance and relative velocity of Andromeda).

Remember the CMB light originated everywhere. So there will always be a distance such that light originating from that distance is just reaching us now. Cosmic expansion doesn't come into play here.

> The Andromeda galaxy is expected to collide with the Milky Way in approximately 4.5 billion years. Does this time take into account the expansion of space in between the two galaxies?

Space expanding doesn't physically do anything. It's just a convention that's useful in some contexts. (It represents a choice of coordinates on spacetime.)

Since the misconceived reification of expanding space is pretty deeply ingrained in the public consciousness, here are some articles discussing the point further.

(1) A diatribe on expanding space. This is pretty technical, but it's the most direct attack on the idea of expanding space. One key quote is that

> there is no local effect on particle dynamics from the global expansion of the universe: the tendency to separate is a kinematic initial condition, and once this is removed, all memory of the expansion is lost.

For example, the Milky Way-Andromeda system is no longer expanding, so cosmic expansion is simply no longer relevant to it.

(2) The kinematic origin of the cosmological redshift. Very well written and less technical, although there are mathematical arguments. The main point of this article is that the cosmological redshift -- often framed as a consequence of space expanding -- is more precisely viewed as just a Doppler shift.

(3) On The Relativity of Redshifts: Does Space Really "Expand"? The least technical of the batch. This article is also focused on the interpretation of the cosmological redshift. It includes the choice paragraph:

> While it may seem that railing against the concept of expanding space is somewhat petty, it is actually important to set the scene straight, especially for novices in cosmology. One of the important aspects in growing as a physicist is to develop an intuition, an intuition that can guide you on what to expect from the complex equation under your fingers. But if you assuming that expanding space is something physical, something like a river carrying distant observers along as the universe expands, the consequence of this when considering the motions of objects in the universe will lead to radically incorrect results.

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That can be in rurla areas, in urban landscape it can be less smog, as rainfall drags it to the ground.

Hey, my field here (still in pharm school, but I'll specialize in delivery).

1. Getting an approval is a long, hard and expensive process, all things that you want to avoid. On top of that, a patent expires after a while, so other companies who didn't spend money on the research process can manifacture the med and sell it (the so-called generic drugs), BUT you can extend the patent if you re-patent it in a different-enough formulation.

2. Each route has its advantages and disadvantages, and the main ones are actually different enough to just choose in advance depending on the effect you need (instant vs slow release, for instance). However, there are A LOT of finer delivery methods which can be used, that can modulate the release (targeting something like a tumor or releasing through a precise pattern like concerta / ritalin XR, not to mention advanced methods that involves heat or other external stimuli).

Now, given 1) and 2), you can understand how the first try for at least a general method, the ones that fits the reason why it's being developed, patent and get the AIC (Italian for Autorizzazione all'Immissione in Commercio, don't know the English term, basically authorization to sell it) as soon as possible, after refining the chosen one.

After it's on sale, they'll find a way to repurpose or formulate it differently, maybe trying for an XR version, and testing for different delivery methods, which will be patented right before the other one expires. They calculate it to day precision.

Expansion is a big factor but you can think of the light of the CMB as having originated from everywhere. The part of the CMB we observe is a growing bubble. The light is traveling uninterrupted after having been emitted in the early universe.

To the second question, the expansion of space is not that significant between nearby galaxies.

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Also depends on the nature of the chemical and the desired results, and how anxious the developers want to bring it to market. For example, certain compounds are easy to inject, but developing an oral formulation (which are generally more desirable) would take longer. But if the drug is the first drug in a new class, the first to market status could trump oral availability.

Also, sometimes drugs are for specific applications - there is no point in testing a topical agent orally. Or the rectal absorption of a drug intended for join injections.

But sometimes it happens that a smart person thinks "hey, this drug I've been injecting could work on hemorrhoids." So then that might be studied.