♪♫ caek's corner ♪♫

dear caek,

i was wondering about space. so if the universe exploded and stars are just explosive accretions of mass and eventually everything will be really far apart from everything else, why is it all going to collapse sometime?

or is some stuff getting farther away from other stuff at a significantly faster or slower rate? because maybe then the combined mass of the entire universe would be enough to decelerate one of the more rapidly escaping densities such that it would fall back into some orbit---do this with everything in the universe and it eventually just settles into a steady state, right?

anyway thanks for being a scientist,

gbx

what is the difference btw space and time?

why does it matter what's happening in space when ppl are suffering here on earth

Are you the kind of guy who can pull off wearing all-white shoes, white pants, and a white shirt?

dear caek,

if you were in a film then who would play you?

^^relevant to my interests xp to lamp but this works too

i think maybe time and space are the same thing because at some point it is impossible to reconcile velocity and position.

i think if you take a space journey at a speed of .4 c you can come back to earth and play yourself as a baby

goin on a star voyage...movie star, that is!

is "space" an appropriate answer to "whats yr fav color" i mean is space a color cause pretty sure it is u might want to look into that

dear caek,

if you were in a film then who would play you?

dude from match point??? http://www.tribute.ca/tribute_objects/images/stars/matthew_goode.jpg

i was wondering about space. so if the universe exploded and stars are just explosive accretions of mass and eventually everything will be really far apart from everything else, why is it all going to collapse sometime?

it's not certain that it will, but if it does it will be due to gravity. there are three things: (i) the force of the big bang, which was big, maybe too big for anything to overcome and is still totally dominant on intergalactic scales; (ii) gravity, which adds up to quite a lot given enough time and everything in the universe to work with; and the third thing, which acts in the same way as the explosion (i.e. drives things apart) is ~~dark energy~~, which no one really understands and if basically some bullshit to sell new scientist [*]

so the question is, when you add these three together, what is the ultimate fate: collape, expansion, or exquisitely balanced steady state. i am not a cosmologist, so this is not really my area, but my understanding is that the latest thinking is that it's the last one, yeah. but the steady state we're headed for has galaxies much further apart than they are now, and is going to be an extremely boring place.

[*] this is not entirely fair. there's pretty good evidence that something other than just (i) and (ii) are happening, but we have no idea what, so we call it dark energy.

what is the difference btw space and time?

― Lamp, Saturday, December 5, 2009 9:37 PM (11 minutes ago) Bookmark Suggest Ban Permalink

in relativity, the only difference is you cannot travel backwards in time. it is otherwise identical to the other dimensions. in the real world, time is time and space is space, and the difference is obvious although i once did get so perfectly drunk that i was experiencing the world in derivatives with respect to time. totally amazing.

why does it matter what's happening in space when ppl are suffering here on earth

― harbl, Saturday, December 5, 2009 9:39 PM (11 minutes ago) Bookmark Suggest Ban Permalink

it absolutely does not matter what is happening in space, other than to the extent that knowing about it makes people happy. anyone who tells you that pure astronomy is anything other than culture is lying. i feel v. strongly about this and get into many arguments with astronomy geeks at work. i think it is totally dishonest to suggest that what astronomers do is important in the true sense of the word.

oh yeah i can def understand that. it's why i quit doing math&physics after undergrad. thanks 4 ur time ; )

Are you the kind of guy who can pull off wearing all-white shoes, white pants, and a white shirt?

― big darn deal (Z S), Saturday, December 5, 2009 9:40 PM (13 minutes ago) Bookmark Suggest Ban Permalink

i always wore white chuck taylors between the ages of 16 and 25 and that looked ok, but i have a very fair complexion (i got hospitalised with sunstroke in cornwall once), so i don't think that would be a good look for me. i think it works well for pierce brosnan though. he has amazing hair imo.

oh yeah i can def understand that. it's why i quit doing math&physics after undergrad. thanks 4 ur time ; )

― harbl, Saturday, December 5, 2009 9:57 PM (45 seconds ago) Bookmark Suggest Ban Permalink

it's the same reason i quit philosophy early in my undergrad. both astronomy and philosophy don't matter at all, but worrying about whether we exist or not did seem to be taking the piss a bit.

what is the best galaxy and why

pics ok

dear caek,

if you were in a film then who would play you?

― caek, Saturday, December 5, 2009 9:42 PM (17 minutes ago) Bookmark Suggest Ban Permalink

great question. the answer is simon pegg.

dear caek,

what is your favourite john updike quote about astronomy?

although i once did get so perfectly drunk that i was experiencing the world in derivatives with respect to time. totally amazing

o_O

caek: does the massiveness of space ever seem sinister to u?

is "space" an appropriate answer to "whats yr fav color" i mean is space a color cause pretty sure it is u might want to look into that

― ice cr?m, Saturday, December 5, 2009 9:46 PM (14 minutes ago) Bookmark Suggest Ban Permalink

that question has an answer thanks to the nerds at at&t bell labs:

http://i50.photobucket.com/albums/f325/caek/bellhorn.jpg

they may not do mms messaging or tethered mode, but this is cool:

http://lambda.gsfc.nasa.gov/product/map/current/pub_papers/fiveyear/basic_results/images/med/gh5_f12_PPT_M.png

what is the best galaxy and why

pics ok

― crazy farting throwback jersey (gbx), Saturday, December 5, 2009 9:59 PM (8 minutes ago) Bookmark Suggest Ban Permalink

imma get back to you on that one.

dear caek,

what is your favourite john updike quote about astronomy?

― caek, Saturday, December 5, 2009 10:00 PM (7 minutes ago) Bookmark Suggest Ban Permalink

caek: does the massiveness of space ever seem sinister to u?

― Lamp, Saturday, December 5, 2009 10:05 PM (2 minutes ago) Bookmark Suggest Ban Permalink

It is not true that developments in physics go ignored by professional humanists or by the common man. The basic facts get to us all and frame the way we think and even feel. The picture physics paints of the material universe is arresting enough to make the newspapers but far from flattering to our individual identities. Astronomy is what we have now instead of theology. The terrors are less, but the comforts are nil.

-- John Updike, 2005 iirc, Physics Today

seriously though (i) yes, terrifying moments of clarity every year or two (ii) listen to this short story, it will only take you 15 minutes and it is pretty much on the money about the end of time: http://freakytrigger.co.uk/ft/2008/04/a-bite-of-stars-a-slug-of-time-and-thou-episode-5/

a favourite galaxy:

NGC 1300

http://www.phys.ncku.edu.tw/~astrolab/mirrors/apod_e/image/0501/ngc1300_hst_c30g90.jpg

itt a strange man asks you if you saw the massive bar and dust lanes and flocculene on that galaxy

Can you explain a bit more about forces? Like, for instance, is gravity subject to relativity rules - if something starts increasing in mass really fast (uh pretend this is possible I guess), do nearby object start feeling the extra tug immediately, or only after exactly (distance/speed of light) seconds? I guess it must be the latter but why does that make any sense?

M104 (aka the Sombrero galaxy)

http://www.strw.leidenuniv.nl/~broek/pictures/sombrero_galaxy.jpg

she's a beaut

whoa it's like a plate!

M104 u r a treat

how many of the stars i see are actually galaxies

http://i49.tinypic.com/2ez2rs6.jpg

forces are propogated by massless particles. e.g. the electromagnetic force, which is the force that dominates our lives, keeps us warm, prevents us from walking through doors, etc., is propagated by the best known massless particle, the photon.

massless particles travel at exactly the speed of light. therefore forces can only propagate at the speed of light, you are correct.

there is a thought experiment about this involving the sun suddenly disappearing. if this happened then the earth would stay on its orbit for 8 minutes, before suddenly flying off into space, because that's how long light takes to reach us.

the reason all this makes sense is complicated and difficult to explain without getting into special relativity, which is not my strongest subject, and not something i've ever been good at teaching. but perhaps if you're comfortable with the idea that you can't send information at faster than the speed of light, then it would make sense to you that you can't have forces that operate faster than that (or instantaneously) because they could be used to transmit information at faster than the speed of light.

this wikipedia article makes a decent stab at this. of course once you throw in quantum mechanics all hope of understanding this is lost, because that stuff makes no fucking sense whatsoever.

how many of the stars i see are actually galaxies

― crazy farting throwback jersey (gbx), Saturday, December 5, 2009 10:22 PM (5 minutes ago) Bookmark Suggest Ban Permalink

not many. with the naked eye, in a dark place, you can see andromeda (m31):

http://www.tcd.ie/Physics/Schools/what/galaxies/m31_ware_big.jpg

and m33:

http://www.astrogb.com/images/galleria/M33.jpg

in the southern hemisphere you can see the small and large magellanic clouds, which are galaxies too.

however, there are a lot of galaxies. this is the hubble ultra deep field, which is not very pretty, but may give you an idea for how many;

http://imgsrc.hubblesite.org/hu/db/images/hs-2004-07-a-large_web.jpg

pretty much everything you see there (except the two twinkling things, which are stars, is a galaxy. there are about 10,000 in that image. that images is 1 ten millionth of the total area of the sky. and the hubble is only seeing a tiny fraction of them.

http://i49.tinypic.com/2ez2rs6.jpg

No : (. Law 4: "if thermal undershorts are worn, they are of the same main colour as the shorts"

dear caek,

what is a cool video about angular momentum?

great question. i would have to say:

https://www.youtube.com/watch?v=r__nGqGpTD8

I'd agree with you, xp, but Keith Hackett says: "Yes. Let the substitution go ahead because there's also nothing in the laws to prevent playing in furry trousers – and there's no reason for you to intervene because the trousers are clearly not dangerous to either the player or his opponents. You should monitor the situation though in case problems do occur – at which point you'd have the authority to have him removed, even if the side have used all their substitutes."

So I asked Mrs K to arbitrate and she said: "Yes, for the humour value."

xxxxpost

The abyss gazes also...

These pictures - they are amazing.

xxp, some people are pragmatists or intentionalists, myself i am a textualist.

dear caek, what is a pretty thought about people and stars and shit?

For many years I put up a Day of the Dead altar every November 1 in my Mexico City apartment. I did this in collaboration with the woman who used to take care of it and me; Señora Jacinta Cruz Ilescas, a Zapotec woman from a village in highland Oaxaca where traditional dress has long disappeared and only Spanish is now spoken. In a fever of creative ambition, we would find new ways each year to suspend cloth backdrops on a bare wall. We would pin paper cutouts to the cloth; wrap and stack shoeboxes to create small free-standing altars on the larger one; surround portraits of the departed with fruits and the fruit with flowers and small plates of the favorite traditional foods of the deceased. Then we would fit a dozen prayer candles among the dense display of offerings and try to make the whole thing fireproof.

Finally, after we had admired the result and pointed out the current altar's virtues with regard to the previous year's, Señora Jacinta would invariably say, "Ah, señora, but if we were in my pueblo, we would be able to uproot a vine chock-full of jicamas, and make an arch for the altar with it. That way it would be right." Years ago, I read that the Maya people of southern Mexico also make a ceremonial arch from jicama vines, and they still remember why. The radish-like jicamas, which hang down from the vines, and have brown skins but are white on the inside, represent the stars of the Milky Way.

Another cool food-space connection: galaktoboureko! but that's probably just because it's Greek.

i think it is totally dishonest to suggest that what astronomers do is important in the true sense of the word.

― caek, Saturday, December 5, 2009 9:53 PM (1 hour ago) Bookmark

i think this about a lot of intellectual careers (incl. my own, if i ever manage to have a career), but as long as you're honest about it, it's ok to do something just because it's really interesting and somebody's willing to pay for it.

yeah, i agree. i've done my phd during a weird time, and i think it's worse than usual at the moment. funding situations occasionally become so desperate (e.g. now) that you see people convincing themselves that what they do is v. important so that they can convince other people. i think this is disastrously counter-productive, both for the long term attitude of the public toward science (i genuinely worry about what's going to happen when the science results start coming out of the LHC and the electorate are going to be like 'are you fucking kidding me?') and for our internal intellectual health (as big bad betrand russell said, "One of the symptoms of an approaching nervous breakdown is the belief that one's work is terribly important.")

Another cool food-space connection: galaktoboureko! but that's probably just because it's Greek.

galak = milk, hence the milky way is a galaxy. i was not aware of those cakes though. they look good!

awesome thread!

w/r/t: https://www.youtube.com/watch?v=r__nGqGpTD8

do you, caek, condone the practice of dress shirts tucked into shorts?

I do not condone the practice of adult men wearing short trousers at all, but that is next level. I condemn it!

I do not condone the practice of adult men wearing short trousers at all

says the referee

dear caek, what was a cool astronomy picture you saw today?

staring at the milky way whilst getting directly blasted by a solar flare yes!

i bought a NAS

― 𝔠𝔞𝔢𝔨 (caek), Tuesday, August 25, 2020 2:57 PM (one year ago) bookmarkflaglink

i sold it

― 𝔠𝔞𝔢𝔨 (caek), Wednesday, 15 December 2021 20:13 (yesterday) bookmarkflaglink

i hope my girlfriend don't mind it

http://www.jwst.nasa.gov/ is going up in a few years. that's a 6m mirror. going to be a pretty big deal iirc.

― caek, Wednesday, March 3, 2010 8:14 AM (eleven years ago) bookmarkflaglink

"Oh noes, we forgot to take off the lens cap!"

lol "a few years". i'm not sure how late it actually ended up. five years?

Originally planned to launch 2007, then in 2005 they pushed out to 2013.

christ

yup, but a lag of 15 years wouldn't even register on a geologic time scale

Fuck, the mirror is foggy. I repeat, the mirror is foggy. Mission failure.

we're 3-4 months away from knowing if it all works iirc

camera pans up to reveal a giant eye staring into the telescope

https://www.youtube.com/watch?v=MdfUSNzc0Xk

was looking for a more detailed story about the one of the early engineering images from JWST and ended up on phys.org. good site!

two delightful stories

https://phys.org/news/2022-03-gaia-snaps-photo-webb-l2.html
https://phys.org/news/2022-03-asteroid-impact.html

Gaia snaps photo of Webb at L2

best spacecraft friends

maybe not useful for caek, but the sixty symbols youtube channel did just post a little bit of discussion about the calibration image.
https://www.youtube.com/watch?v=Zbj8pMfK9Ek

I wrote a paper with that guy!

cool! i had wondered if he was someone you'd run into before

good livestream

At their worst, the Nautilus dive streams are fascinating. At their best, you watch new species being discovered live. Particularly recommended if you enjoy space launches. https://t.co/VcjPcWKmCT

— Charlie Loyd (@vruba) March 23, 2022

hi caek, nice corner!

feel free to ignore any or all of this, which starts the chilling words, "i have a comment and then a question"

the comment is that the james webb telescope ("the webb?" <-- a question inside the comment) has helped me understand, more concretely, some familiar old ideas about relativity and time travel in a more concrete way. i've understood that the light that we see from distant objects like stars are images of a previous time, since the light emitted has to travel for years (a "light year", if i may coin a phrase) before it reaches us. but i never really thought about the ramifications of capturing the light of more distant stars than ever before. it's just "light" but it's also an image of the distant, distant past.

that got me thinking (yes this is still the comment - i am seriously replicating a real life "comment and then a question") about what it means to travel along the path of that light, back toward the origin of the star, realizing that in a way it would be like accelerating into the past. if you stood on earth and received the light at normal speed (light speed), you experience the past of that distant star at a steady, human/earth rate. but when you begin to travel into the light, your experience of their past happens more rapidly - it's all in there, it's just more compressed (?). and that, if you could travel against the light quickly enough, you experience all of the billions of years of its history in the time that it takes you to travel from earth to the star.

and then (comment!), in the other direction, that you could could effectively freeze one's experience of time by "riding along" the path of the distant star's light at the exact same speed, always seeing it in the same way. and that in a sense you could "reverse" time if you could move even faster than the speed of light, and traveled back to an earlier form of the light/image. it's cool that the images from the webb make that kind of idea of more understandable and real (at least to me).

*loud booing from a 4th year grad student*---alright alright so here's my question! jfc.

all of that got me thinking about where the origin of the big bang is supposed to be, and how seeing more distant stars could help us understand our own galaxy's position in the universe. i've had the idea that the big bang is in the "middle", with matter generally heading outward ever since. that might be wrong in itself, i don't know. [coughs directly into mic, saliva sounds]. would the webb's ability to see farther than ever before provide additional data about the previous celestial coordinates/paths of existing stars/objects that we already knew about? is it possible to "see" that an existing galaxy briefly obscured another galaxy or affected its gravity/path at some point in the past?

i don't know, you can disregard and ad lib freely, i'll take my answer off the air, thank u caek

"if you could travel against the light quickly enough, you experience all of the billions of years of its history in the time that it takes you to travel from earth to the star."

"effectively freeze one's experience of time by "riding along" the path of the distant star's light at the exact same speed, always seeing it in the same way."

these things are not possible, because, however fast you go, in whatever direction, light travels at the speed of light relative to you. that's special relativity baby.

"the webb's ability to see farther than ever before"

i think you're a bit confused about the way in which it is true. imagine a sailing boat. the webb telescope doesn't see further by moving the horizon away from us. things still drop below the horizon when they drop below the horizon. the webb allows us to see further by having better eyesight. i.e. at a given distance, the webb can see fainter things than existing space telescopes. in the case of telescopes, the horizon is set by the speed of light. it is essentially the speed of light x the age of the universe away from us. no innovations in telescope design will ever change this.

if I may throw some of my thoughts in the air here

what we see is long gone - it either doesn't exist anymore or it's far away from where the light started its travels (point at the Sun: you're wrong, you're pointing at where it was 8 minutes ago)

the big bang happened everywhere. the whole universe was there when it happened. (/it's still happening)

thanks caek!

i do want to say that for a brief time, i felt like i could barely understand time travel and how it might work, and in that moment i was standing on the shoulders of nincompoops

Time does slow down for you the faster you travel though (i.e. In your subjective experience, external events speed up). This is the probably the second easiest way to travel forward in time, the first being cryogenic freezing (pending first successful thawing of human subject).

Time does slow down for you the faster you travel though

This is definitely true in Nebraska

but the very easiest way of all to travel forward in time is to do nothing special at all and just let it happen

I knew i should have specified faster than one second per second.

faster than one second per second

but cryogenic freezing doesn't alter the pace of time itself; it merely suspends one's perception of its passage even as time galumphs along at its normal rate.

If I pass through a wormhole or race off and back at light speed or accidentally fall into a cryogenic freezer, what's the difference when I appear/arrive/wake up in the year 3000?

there is no difference in your perceptions, but there is a major difference in the physics

first of all, techno

xp

i hold that the techno would be extremely different and immediate

besides that, energy lasers have replaced bullets, every door requires a digital key card, and your name is cobra19

cobra19? What is this, the 2500s?

haha, otm it's true

iirc if you can hit warp 10 you will experience being everywhere all at once, but then you turn into a lizard

The W boson appears to be heavier than expected:

https://www.science.org/doi/10.1126/science.abm0101

Yeah I've seen skepticism on this from people who know more than me, gonna need a ruling from caek.

Not my area at all but here’s a couple of posts on it by reliable scientists

https://telescoper.wordpress.com/2022/04/09/massive-excitement/

https://profmattstrassler.com/2022/04/08/a-few-remarks-on-the-w-boson-mass-measurement/

oh! thanks!

The James Webb Space Telescope analysing sound from the heart of the galaxy is amazing. I had no idea this was possible
(film courtesy of NASA) pic.twitter.com/mrOQ0LnlB6

— Chris (@justachrisaway) March 29, 2022

https://www.npr.org/2022/05/12/1098472567/image-black-hole-milky-way?t=1652362048265

https://media.npr.org/assets/img/2022/05/12/black-hole-milky-way-bb0124cb43ed0a77533657759baa424f5d5fce7c-s800-c85.webp

itt: stanm posts hole

pictured: the day after spicy food

how many billions of years do I have to wait before I'm pulled into the giant black hole?

make it now, please

dynamically extremely difficult for anything other than dust and gas to get pulled into a black hole, sorry for your loss.

you might get lucky when we collide with andromeda in 5bn years, but both galaxies are almost entirely empty space, so probably not.

i can wait

fun fact: you could easily fit all the other planets in the gap between the earth and the moon.

cannot stress enough how empty space is.

Andromeda, the closest galaxy, is 2.5 million light years away. 2.5 million years ago, the first homo habilis started to evolve. If humans could travel at the speed of light (in stasis, I suppose), look around a bit, make friends with some andromedans and then come back, what species would they report to, 5 million years in the future? (if they managed to find the solar system and Earth again and something was still alive here, that is).

And that is our closest neighbouring galaxy, remember.

there's a lot of space in space.

[cue Hawkwind's "Space Is Deep"]

dust and gas

ease yourself into
a body bag