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1:44 AM
@GeorgeSmyridis If you want to go the physics route and maintain a high level of industrial employability, go experimental materials, condensed matter or optics. Do not be sucked in by the siren song of theory. Even computation is risky though it at least will give you a secondary set of salable skills.
Also do not---under any circumstances---be sucked in by particle- or astro-physics in any form.
Love my particle physics degree. Loved my post-doctoral work. Would probably have made a pretty good industry R&D guy but had a really hard time getting my foot in the door and my colleagues report similar things.
And if you are wondering I ended up professing at a very small state U with no money, equipment, lab space, time off or assistants for research.
But at least like the teaching gig.
 
1:58 AM
@dmckee Are the experimental materials not quite concentrated in certain parts of the world (say, fabs)? And not only that, if you know how to do one experimental technique, sometimes they are (or seem to me) so highly specialized that it can be difficult to switch to something of more interest to industry. I have seen a lot of my friends who had chemistry majors (experimentalists) have problems getting employed. This could of course be country-specific.
 
2:22 AM
@dmckee I disagree. With observatories like LSST coming up soon, in addition to the already-existing set of observatories, data analysis is pretty big in the astro groups (just have to find the right advisor, of course). This would go a long ways to industry jobs in data science
 
2:33 AM
@KyleKanos It should, but it is hard to get a foot in the door. My big contribution to two of my projects was analysis coding. I'm a pretty decent coder with some "big picture" understanding and a lot of experience in distributed cooperative development.
The best programming job I was able to get interviews for payed about what i got as a graduate assistant.
 
Getting the foot in the door in industry always amounts to one thing: knowing someone there first
 
@KyleKanos Uhm. Evidently I don't know the right people.
 
I'm running into the same trouble :(
 
I did eventually find some good advice on tuning my resume for industry and was starting to get nibbles when my current job dropped in my lap.
Big firms almost all have a idiot computer program look at your documents first and they can circular file them if they don't get enough key-word matches.
So you phrase everything in industry terms in hopes that it will actually get to a hiring manager who can bring human intelligence to the job.
 
@dmckee Well it is always a risk for a company to hire someone who may or may not want to stay long term, so naturally they'd prefer someone who has shown interest (through part-time jobs, internships, whatever), which of course add to the difficulty.
@dmckee True to a certain extent. Often for PhD level jobs you might want to go through a recruiter, though, who will probably get your CV read by the guys actually making hiring decisions. A poorly written CV or a less than excellent fit will get a quick rejection, though.
 
2:40 AM
I've talked to a grand total of one (count her) recruiters who professed any interest or experience placing physicists.
Mind you, she did find me a back up gig: writing safety procedure documents for nuclear power plant operations.
Calls for a Ph.D. and practical experience with operations in radioactive environments and sounded like it was even more boring than patent clerking.
I did some safe procedures documents while I was postdoccing. It's detailed oriented and mind-numbing.
 
@dmckee Well I remember dropping my CV to one of those online job sites (not submitting it to any particular job at that time, but making it visible to people hiring), and had recruiters calling me the very next day.
In the end, I did not get my job through a recruiter. I did apply through them to one, and was rejected by the company out right (without invitation to interview) because my background was not mathematical enough for them.
I was quite surprised by the reason, but at least they did have a look.
 
Hey, python users this is useful.
 
 
4 hours later…
6:27 AM
Congrats @ManishEarth on your science mod positions :-)
 
thanks
 
6:44 AM
@ManishEarth Congratulations Manish !
@ChrisWhite Do you wear a Spock wig ?
 
7:33 AM
That was a wig? :P
 
 
3 hours later…
10:35 AM
wondering once again if my question should go here or on math.se
 
@paul23 what's the question?
 
0
Q: Hyper/parabolic kepler orbits and "mean anomaly"

paul23In an elliptical kepler orbit there is an easy recipe to describe the motion/position of a satellite at time $t$. One just follows the following steps - an important detail for me is that the numerical part has always the same error, the error doesn't increase with time, nor is it based on the ti...

 
seems like physics
@ChrisWhite some unsolicited (and probably not even that useful) advice: if and when you do make the decision to leave academia, don't waste any time doing so
 
 
2 hours later…
1:07 PM
@dmckee @alarge @ChrisWhite @KyleKanos @ACuriousMind So are there any advantages as far as job prospects are concerned to become a physicist than an engineer? They all get similar jobs anyway :/
 
1:18 PM
@skillpatrol Why? We were all involved in a conversation yesterday (last night for some), so he's trying to continue it
 
sorry, didn't know that :(
 
@GeorgeSmyridis I honestly don't know what the advantages/disadvantages would be, as I've got a physics degree.
@skillpatrol Scroll upwards, part of the conversation is at the top of the page :shrug:
 
1:49 PM
@GeorgeSmyridis Depends what engineering. Some disciplines require proper licensing.
In America, we have the Professional Engineering exam, which you cannot take unless you have a degree in engineering IIRC.
 
2:10 PM
Chat session coming up in a couple hours... I can actually be at this one! (yay)
 
Yay!
 
3:00 PM
I'm kinda surprised that this even needed to be asked:
15
Q: Why are Rocket engines at the base of the rocket?

DeepI don't know much about Rockets, but all that I have seen, from the Saturn V to SpaceX's Falcon 9 have the engine at the bottom. Doesn't this make the Rocket really unstable, like balancing a pencil on your finger and trying to lift it up? Why do we not pump the exhaust gases up to the top of the...

 
I would be in the chat session but I got kicked out of my cubicle
What time?
 
@0celo7 A little less than a hour
Also, 1. You had a cubicle? 2. You got kicked out?
 
@KyleKanos Those answers are really bullocks lol
highly upvoted bullshit
 
@ACuriousMind 1. Yeah, so? 2. More senior interns are despotic rulers.
 
3:20 PM
Ahhh, finally back after vacation. How is my favourite physics chat room?
 
Deskless
 
Also, @0celo7, I'm not sure what game that was, but it sounded like D&D. Why do you think I know anything about it?
 
@GeorgeSmyridis Perhaps you misconceive that someone with a BE cannot pursue a research career.
 
@JimsBond Huh?
 
Jun 25 at 1:12, by 0celo7
@ACuriousMind @ChrisWhite @JimsBond Is there any special reason why the Steel Mace is doing crazy amounts of damage? It's 34 (at lvl 1) vs. ~25 for a steel longsword and when I spawned Daedric weapons using the console, they're doing a lot less damage.
 
3:21 PM
It was probably Skyrim.
Yeah, Skyrim.
 
Ah, didn't play that either
But I see why you thought I did
 
I just referenced the PC gamers who were in chat at the time.
 
Console > PC
 
^^^^^^Asychronous communication protocol.
 
@KyleKanos Defense?
 
3:23 PM
With consoles there is no fuss.
 
PC has better graphics
 
@JimsBond Every NES, SNES, Genesis, N64 and PSX game in existence
 
@KyleKanos all available on PC
 
Modding ruins blood pressure. Freaking mod conflicts and load order.
@JimsBond Nope.
 
@JimsBond (a) not true (AFAIK), (b) they don't play as they do on console
The emulators do not actually replicate the system identically, just emulate it for playability
 
3:25 PM
I have emulators for all of them, never found a problem in finding games or playing them
 
How is that not illegal?
 
Thankfully, you don't know my real name
 
@JimsBond Uh, it's Jims Bond, duh!?
 
You're Bond, Jims Bond.
 
I think the FBI can easily identify The Jim.
 
3:27 PM
The thing about being a super famous secret agent is that everyone knows who you are. It's not a secret anymore
 
Well, technically, James Bond isn't a spy, but an ornithologist
 
@0celo7 The emulator isn't illegal to own. It's illegal to make, but not own. And you can use it legally if it's for mounted games that you actually bought and own
 
@KyleKanos Why no GCN and Wii in that list?
 
@JimsBond It's illegal to make an emulator? I thought it was just illegal to DL the ROMs
 
How can you DL ROMs legally? It's stolen property.
 
3:30 PM
@KyleKanos It's illegal to make unless you purchase the rights from the console developer
 
@0celo7 Because classic VGS > next-gen VGS
@0celo7 For cartridges, you need special connections. For discs, you can just rip it to ISO
That is, special connections to connect it to the computer to take the data
 
and ripping discs to iso for your own personal use is legal
 
^Even for making personal-use copies, AFAIK
 
You said you had no trouble finding them, not buying and ripping.
I'm asking how finding is legal.
 
@0celo7 It's legally ambiguous
 
3:32 PM
@0celo7 How is doing a Google search illegal?
 
@KyleKanos You know what I mean.
 
and if after that search, my computer "accidentally" downloads it.....
 
I think identifying PC rips is more difficult than console ones, ain't it ?
 
PC games have lots of DLC and bonus content for those that get updates and have legit accounts. They know how to incentivize people to buy the game and make money in the event that people pirate it anyway
Besides, at < $1/h of entertainment, who needs to pirate VGs?
 
3:38 PM
Poor college and high school students.
 
@JimaBond Console games don't have that ?
Incentives?
 
@KyleKanos that's a shit DL speed, no wonder
 
I always used to download the demo versions of games that I couldn't get full on the Sony store for my PSP. That'd leave me drooling for the full version. How less an incentive is that ?
 
3:54 PM
?
 
?
 
?
 
3:56 PM
!
 
(ノ♯`△´)ノ~’┻━┻
 
ᕦ(° Д°)ᕤ
 
⌨ █▬▬◟(`ﮧ´ ◟ )
 
3:58 PM
}8^)>
 
You people are insane.
 
(((φ(◎ロ◎;)φ)))
 
:)
Chat time!
 
Adventure time ! oh wait no that's something else
 
欢迎你们!我们来聊聊天儿。
oh wait
bold makes it official
:-P so, yes, chat session time! Welcome all. Who's here?
(who hasn't been posting silly symbols)
 
4:03 PM
I'm half here
 
(all of us posting silly symbols now feel sheepish...)
 
Wake up sheeple !
 
@TerryBollinger 哈哈,没关系 :-P
(haha, no problem)
 
The Chinese are invading
 
@Bosoneando, nice name and symbol there.
 
4:04 PM
@DavidZ I just googled that to figure out what it meant
And 0.5 seconds later I pop back to see you giving the answer already
 
Argh, I'm behind before starting!
 
reminds me of a funny story my friend was telling about Chinese speech and laughter, but I can't really do it justice in chat
Anyway, anyone have something to talk about today?
 
Hey, anyone read Garrett Lisi's new paper, released yesterday?
 
No, can you post a link?
 
4:07 PM
Great abstract.
 
True
 
Also, here's his Google+ announcement:
@ACuriousMind It really is already one of my all-time favorite abstracts...
Interesting how he deals with GR...
A very, very different approach from string theory.
String theory assumes spaces as a given, as a medium for vibration; Lisi instead tries to break space itself down into more fundamental parts (is my very early reading).
OK, has everyone now read and digested the 42 pages?... :)
 
On a different topic, I keep think we really need a definitive Q/A on "what is time dilation"
I keep seeing questions about time dilation that can't be answered because the OP has completely the wrong idea about it.
 
@JohnRennie Really? I did not realize it was controversial?
 
@JohnRennie is it like in stargate?
 
4:15 PM
@TerryBollinger It's not controversial for anyone who understands differential geometry
 
@paul23 Bad, spank!
 
But the vast majority of questions have no real idea what time dilation is or how it works.
 
@JohnRennie If a canonical answer could make differential geometry conceptually accessible even to early math types... hmm.
 
I have started drafting a canonical Q/A several times, but I've yet to find a really clear way of explaining it
 
@JohnRennie Have you posted any of that in any current answers (or elsewhere)?
 
4:17 PM
I've attempted lots of answers relating to time dilation, but none that give a really compete picture
 
@TerryBollinger Not sure you are comparing the right things here. When I look at the actions he writes down, they seem to reproduce the ordinary SM and gravity actions (which he says explicitly at the end). But it is known that the action for gravity is not quantizable in a renormalizable way, so this paper does not seem to tackle the question of constructing a quantum theory of gravity, while string theory does.
 
@ACuriousMind I... think I agree with you? I've been looking so far just at the group stuff, not really the GR parts. But yes, it does not take a quantum gravity tact at all, does it?
 
On another different topic, I've just noticed my daily rep on the SciFi SE is greater than on the Physics SE. That's a first.
 
@JohnRennie for what it's worth, I always figured that as an indicator of someone who shouldn't be asking about time dilation here. Not that I would be opposed to having a canonical Q&A if you want to do it.
 
Does it influence sattelites/rockets?
 
4:20 PM
@JohnRennie What is the main conceptual issue you'd wish to explain? I have the impression that the issue is not that people can't find explanations of time dilation, it's that they cling to some of their classical (or unphyiscal) preconceptions when interpreting these explanations, and then get horribly confused.
 
@JohnRennie I keep wanting to look for such a model, but also keep not having time. I think it's a great goal, and I suspect it is doable.
 
yes - make a Q&A, no - > boring no need
 
@JohnRennie I've never even looked there, didn't know it existed.
 
@ACuriousMind the elapsed time is the proper length of the trajectory, which is different from the coordinate time of a different observer
But whenever I've tried to write the definitive Q/A I keep getting bogged down in explaining how proper time is calculated
I've yet to find really good, succinct, clear way to explain it
@TerryBollinger quite a few of us physics heads are on the SciFi SE. dmckee has quite a high rep there.
4
Q: Does the Juice of Sapho do anything other than stain?

PraxisMentat Masters regularly consume the Juice of Sapho, causing their lips to stain. According to the Dune Wiki, Sapho, or more commonly the Juice of Sapho, was a high-energy liquid extracted from the barrier roots of the planet Ecaz. It was used by Mentats who claim that it amplifies the me...

 
@JohnRennie I might suggest a picture
 
4:27 PM
@JohnRennie I'm tempted to talk about a paper I'm writing on what seems to be an overlooked invariant when slicing space time... no, not yet. SR is even cooler and stronger than it might seem from geometry alone.
 
@JohnRennie Perhaps then the best case would be write a canonical Q&A about calculating proper time and one on time dilation?
 
That was the sort of description I was trying to write
 
it's giving me "access denied"
 
@KyleKanos worth a try. The thing is that it isn't obvious why you're rambling on about proper time unless it's in the context of time dilation.
 
not that it matters, really - I don't have any specific ideas of what would make a good picture
but I usually find that things which are hard to explain with words are a lot easier with pictures
 
4:29 PM
@JohnRennie I'll look up the sci fi group
 
@JohnRennie Well circular references are totally fine by me :)
 
@DavidZ Try now ...
 
it works
 
@JohnRennie that reminds me of an animated figure that used to be on Wikipedia, but I could not find it in a quick look.
 
@DavidZ the diagram was going to start with the Pythagorean expression for ds, then explain that in SR we use the Minkowski metric instead. But I struggle to explain this clearly.
 
4:34 PM
Hmph, looks like they removed it...
 
@TerryBollinger I think I may know the one you mean, but I can't find it either
@JohnRennie huh, yeah, well like I said I don't have any groundbreaking ideas
It's not exactly easy to visualize the Minkowski metric in a way that clearly shows its differences from the Euclidean metric
@TerryBollinger :-(
 
@DavidZ It does feel like roughly the right direction, though I wonder if a bit of creative slicing of the block universe might convey some of the issues too...
 
Actually I started by trying to write the definitive article on the twin paradox, but realised I needed to explain time dilation to do it. Hence the attempt to write an article on time dilation.
 
@JohnRennie I dove in deeply to some of the twin paradox descriptions once, and too many of them are sloppy or flat-out wrong. A good description needs to bridge Minkowski and Euclidean, and as you noted that is just not easy to do in a clear, understandable figure.
 
The point about the twin paradox is that the stay-at-home twin calculates proper time using the Minkowski metric while the travelling twin uses the Rindler metric for all or part of the trip.
But I find myself embarrassingly unable to calculate geodesics in the Rindler metric.
Although I discovered something surprising along the way ...
4
Q: Trajectories in Rindler space with zero net time dilation

John RennieI've discovered a family of curves in Rindler space that have zero net time dilation. However I struggle to see why this should be so, i.e. what the physical significance of these curves is. My question is can anyone give an intuitive explanation for why these curves have zero net time dilation? ...

 
4:41 PM
@JohnRennie One observation: Any diagram really needs to push hard on the idea of true interchangeability of space and time. I don't think that gets conveyed well enough usually.
 
interesting...
 
@JohnRennie Reading...
Whoa, that's interesting. Will look at it after chat, though; you don't ask trivial questions!
 
@TerryBollinger If it was trivial I could have answered it myself :-)
I suspect there is absolutely no physical significance to my discovery and the zero time dilation is accidental. It was a surprising result though.
This assumes of course that my numerical calculation was correct ...
 
Hey, a small observation, tangential: For any isolated system of mass particles, there always exists a "fastest time" frame that includes the center of mass of the system. Yes?
 
@TerryBollinger Err, maybe. I'm not sure what you're getting at.
 
4:50 PM
@JohnRennie Pretty much just that: More specifically, if you create a system of particles from a single point in space time, let it expand and get very complicated over time, but eventually require that it all merge back together into a single point again, then the greatest time consumed will always be the particle that never moves away from the start.
Not profound at all, just interesting if you scale it up across larger systems
 
Still chat session time?
 
Yeah, technically it lasts an hour
Not enforced, though
(whatever that would mean...)
@TerryBollinger it's because the longest proper time comes in an inertial frame, right?
 
@DavidZ chat hour police, that's an interesting concept...
 
haha
 
@DavidZ Sure. Again, not profound, just interesting if applied hierarchically.
Alas all, I must leave a bit early today. @JohnRennie, interesting stuff and a cool question, thanks for sharing so much.
 
4:56 PM
We might be winding down anyway
 
I have to be going too.
Bye all.
 
see you!
 
Looks like I killed the session.
 
nah, blame the uncertainty principle
not the Heisenberg one, but the one that says all measurements come with an uncertainty of 10% or so
 
10% on 5 or so inches can make all the difference
 
4:59 PM
Pff I just read a topic: "I discovered by look at glibc (gcc libary) that the sine of small numbers is the number itself". - Good job missing a major step in your mathematical education..
oh and this is from a quite well "respected" source even.
 
Saying 'what kind of an idiot doesn't know about the Yellowstone supervolcano' is so much more boring than telling someone about the Yellowstone supervolcano for the first time.
2
 
xkcd? what's that?
 
@0celo7 Hey look, I even came back!
@JimsBond one of the coolest and most science-savvy online comics. You should check it out.
 
5:14 PM
ok, bedtime... see y'all later
 
@TerryBollinger Was a joke
 
^ that
 
@TerryBollinger referencing the comic
It's not possible to be in academia and this chat and not know xkcd
Unless you have me and ACM blocked, then maybe.
 
And if I had you blocked, you'd never know it because I'd answer back randomly as if you were there anyway
because, ACM, magnets can be used for anything
 
@JimsBond You'd just randomly @ me and say random stuff? Insidious.
 
5:20 PM
@0celo7 No, I haven't played that game either
 
@JimsBond No one likes Candians anyway; maple syrup is shit; the Queen is a freeloader.
 
@JohnRennie I should finish the thought: For a system of mass point that all originated in a single frame, but has never 're-converged to that frame, do there exist a frame-defined set of mass particles for which elapsed time will always be higher than for any other mass particles?
The answer is of course yes: It will be the set of particles that have remained in the initial inertial frame for the entire time since divergence.
Now while it gets more complicated for something like the Big Bang, the same question can also be applied by scaling upwards to the entire universe.
 
@0celo7 That's okay, we'll figure something out, eh?
 
@JimsBond How can you reference posts if you blocked me? Busted.
 
Which leads to an interesting postulate: Do there exist stars in the universe that have the potential always to demonstrate morealpsed time if you travel to them?
 
5:32 PM
@0celo7 I assume you've just try to call me out on not blocking you. It didn't work. I just assume you say something, hit reply on the most recent post, then change the number to something appropriate. Works every time
 
@JimsBond oO freaking diabolical genius.
 
@0celo7 Because that's the way it works
 
The likely answer is yes. More specifically, they would consist of stars that have remained close to the CMB frame since the original of the universe.
 
@TerryBollinger test
You liar holy shit
 
@0celo7 That number wasn't in this chat room
 
5:35 PM
Hi folks... What the neck is going on?
 
@TerryBollinger nothing, move along
 
Imperial business, move along citizen.
+10 for game name
 
Jimperial business
 
1/10
 
5:36 PM
These are not the droids you are looking for...
 
There are droids here?
 
Does anyone else smell bratwurst?
 
Yes, but only because I'm right behind you
 
Creep
 
ERROR XDG5368 Excessive unresolved external references, shutting down now...
 
5:40 PM
you looked
 
How did you get through Senate security
@JimsBond Wrong!
 
I think keeping your rep at a nice multiple of 5 is reason for some to avoid downvoting — Jims Bond 15 mins ago
There is that too
 
@KyleKanos It's my major reason for or against downvoting
 
Of course, you can play the game so that you just downvote appropriately to maintain the multiple-of-five
(i.e., downvote 5 questions at a time)
 
Yes, but once it's there, it's hard to find 5
plus you have to worry about answers being deleted
 
5:42 PM
Okay, downvote 1 for every 2 Tag Wiki suggestions!
 
@ACuriousMind I got my cubicle back
 
@KyleKanos Will do
 
@0celo7 Yay! So you can return to doing nothing important at a desk
 
@ACuriousMind FYI, I'm writing a letter to a constituent.
 
@0celo7 You mean to tell me some HS scrub is writing me letters in place of the guy I elected into office!?
 
5:49 PM
@KyleKanos No
 
Okay, good.
 
And FYI, I'm a few credits short of an Associate's Degree
So I'm a college mini-scrub
 
that was low
So I deleted it
 
Low?
You don't even have a Ph.D. yet
 
What? Yes I do
 
5:51 PM
You're not allowed to be stuck up yet
 
I've got the degree
 
Prove it.
 
Maybe later
 
That gives you time to forge it.
 
It'd take some gimping to clean up the image (i.e., removing non-essentials & more revelatory information than I'd rather have)
 
5:54 PM
How would I know it's yours?
You could have jacked it from some poor shmuck.
cf. ACM's Alicia Keys thing to get a feel for the rigor of my process
 
You'll have to just trust me
Also: who the heck voted to close this question as non-mainstream!?
3
Q: Is magnetic reconnection reconcilable with magnetic field lines neither starting nor ending?

David HansenAccording to Maxwell's equations, magnetic fields are divergence-free: $\nabla \cdot \mathbf{B} = 0$. If I understand this correctly, this means that magnetic field lines do not start or end. How can we reconcile this with magnetic reconnection?

 
@KyleKanos I am certain you'd have to ask CuriousOne that.
 
@ACuriousMind 20,000 rep magic tell you that?
 
@0celo7 No, educated guess
 
@0celo7 No, basic logic tells me that.
 
5:58 PM
@ACuriousMind Damn. Burn.
@ACuriousMind Also, what's with this burn?
:(
 
@0celo7 You were repeatedly complaining that you were bored by your tasks, I didn't see why you were upset by losing your desk :P
 
@ACuriousMind Bored != unimportant
You don't need to remind me how insignificant I am :'(
Interns are people too!
 
@0celo7 We all are utterly insignificant.
 
@ACuriousMind Not when I cause Chernobyl 2: Nuclear Boogaloo
@ACuriousMind On what scale?
 
@0celo7 Took you a while ;) On a galactical/cosmological scale, of course
 
6:12 PM
@ACuriousMind Like I said, doing things.
Important intern duties.
@ACuriousMind Can I make a galactic nuke?
 
I don't know, can you?
 
Can I make an H-bomb out of the sun?
Is that feasible?
 
@0celo7 Just add more hydrogen to speed up getting to a supernova.
 
Since our sun's not a binary, you'd only be able to get a Type II SN, which means you're adding a few solar masses worth of H....
 
I said speed up, so how much you need depends on how soon you want it to go boom...
actually, can't recall if the Sun is on track for SN with its current mass, or does it just go RGB and shed outer layers?
 
6:28 PM
Just RGB
 
ah, about 8 Msun to get a type II, well, some work to do then...
 
If we could survive the expansion phase, we'd have a pretty white dwarf as a sun
Though, the surface temperature would be at least twice as hot, so that may not be fun
 
it will cool though, just go on vacation for a little while until it's back to pleasant
actually, higher surface temperature + lower surface area = probably lower luminosity, no? might be ok...
 
We've got something like 5 billion years before that happens, so we'll have plenty of time for terraforming other planets (if not straight-up leaving Sol)
With current technology, a shuttle could make it to Pluto (not that it's a planet...) in around 15 years. I think ion drives (or some other currently theoretical propulsion system) are expected to do it in like 5 years
 
Do we even have to go that far? IIRC, the RG would be a few AU in size, but a moon of Jupiter or Saturn might be ok.
would be an awesome view from there, too
 
6:35 PM
Astro nerds...
 
Estimates range between Earth and Jupiter
I suppose we'd have better knowledge of our sun 5 billion years from now, so we'll have narrowed that massive window down some
Of course the problem could be size:
 
Will humans still exist in 5 bn years?
 
even if it extends to Jupiter, Saturn is still another 4 AU out, and RG's are fairly cool
 
The left-most red line (second grouping) is earth
 
u,,,
umm, what's the y-axis?
 
6:37 PM
Relative sizes
Probably radii
 
ah right
 
The big yellow one all the way to the left is the sun
Wish the chart maker ignored that :/
Apparently Saturn has a gravitational attraction similar to Earth
 
or you know, log scale
 
As does Neptune
 
as in surface gravity? (whatever "surface" means for a gas giant)
 
6:39 PM
Yeah, surface gravity
Sorry
This is a partial list of Solar System objects by size, arranged in descending order of mean volumetric radius, and subdivided into several size classes. These lists can also be sorted according to an object's mass and, for the largest objects, volume, density and surface gravity, insofar as these values are available. This list contains the Sun, the planets, dwarf planets, many of the larger small Solar System bodies (which includes the asteroids), all named natural satellites, and a number of smaller objects of historical or scientific interest, such as comets and near-Earth objects. The ordering...
 
np... Titan always sounds attractive in these sorts of conversations
 
Apparently Earth's surface gravity (in units of Earth's surface gravity) is 0.99732
 
heh
probably some detail like average surface gravity vs equatorial surface gravity or somesuch
or just definition then more accurate measurement
 
Agreed, but it's still funny to see it being not 1
 
nod
 
6:42 PM
And Titan's surface gravity is like 0.14 Earth's
So we'd be like Supermen there
And our kids probably wouldn't
 
more like muscle atrophy would set on quickly
nod
 
What if you lift 1/.14 times as much weight?
Can you get jacked in low g?
 
user54412
7:24 PM
@0celo7 When astronauts return to Earth after a couple months in the ISS, they do so in a stretcher because their muscles are so weak they can't even walk. And that's after strenuous exercise for hours every day.
 
7:54 PM
Why doesn't isometric exercises work?
 
user54412
@JohnRennie I don't know what exposition you plan, but invoking Rindler seems complicated. I've always seen the solution to the twin paradox as exactly the same as the Monty Hall problem: There are really three things (reference frames, classes of door), not just two.
 
user54412
There is the Earth twin, the outgoing frame, and the ingoing frame. Similarly, there is the revealed door, the selected door, and the unrevealed door. The error people tend to make is to conflate the latter two things in each case.
 
Both are brutally difficult to explain :-)
 
user54412
Astronomy announcement for those who haven't looked at the sky recently:
 
user54412
Jupiter and Venus are going to be quite close, closer than any time in the next 8 years.
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