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420chan is Getting Overhauled - Changelog/Bug Report/Request Thread (Updated April 10)
How did such an inconceivably awesome object get stuck with such a stupid name? Ignore Report View Thread Reply
Henrietta Levitt - Thu, 18 Oct 2018 20:49:56 EST ID:gVSzJCUs No.57466
File: 1539910196953.jpg -(74041B / 72.31KB, 600x399) Thumbnail displayed, click image for full size. 74041
"Milky Way" sounds so weak and lame for a galaxy, especially the one we're renting. Cant we have come up with a cooler handle for our cosmic digs?
7 posts and 2 images omitted. Click View Thread to read.
Christiaan Huygens - Mon, 03 Dec 2018 11:34:34 EST ID:gRsMKZUR No.57520 Ignore Report Reply
there are dark zones around. probably some near where you live. or get a look at the sky on a nighttime flight, it's pretty awesome above most of the atmosphere
Johannes Kepler - Mon, 03 Dec 2018 20:45:06 EST ID:457vC2+I No.57523 Ignore Report Reply
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Stars, y'say? Heard there's a mighty fine mess of 'em iffen ya know whar to look. Use this here map and prospect yerself a dark zone, pardners:
Riccardo Giacconi - Wed, 05 Dec 2018 10:01:26 EST ID:IpCFcmN3 No.57526 Ignore Report Reply
1544022086421.jpg -(409398B / 399.80KB, 1920x1080) Thumbnail displayed, click image for full size.
that kind of a technical answer i needed, thanks. sorry for being a clueless plebian.

Mars eclipse Ignore Report View Thread Reply
William Huggins - Sun, 25 Nov 2018 21:39:22 EST ID:ckw062Hz No.57504
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if one or 2 of mars moons came between mars and earth during a time where mars is clearest and easiest to see with the naked eye, could one tell the moons were dimming mars red orange light? I understand phobos is really close but could the other moon make a significant enough eclipse or dimming effect to the red dot we see from earth
Fred Hoyle - Mon, 26 Nov 2018 17:36:55 EST ID:457vC2+I No.57505 Ignore Report Reply
Naw, not with the naked eye. Phobos, the larger moon, is only 27 km across.

Perseid meteor shower! Ignore Report View Thread Reply
Johann Encke - Wed, 31 Jul 2013 11:29:34 EST ID:evrPe8Vs No.51233
File: 1375284574338.jpg -(3913B / 3.82KB, 262x192) Thumbnail displayed, click image for full size. 3913
Anyone else gonna observe this beautiful event?

Incase you haven't heard from AUG 12th to the 13th between 10:30PM and 4:30 AM, The sky's gonna light up with massive fireballs brighter than Jupiter.
43 posts and 7 images omitted. Click View Thread to read.
Christiaan Huygens - Sun, 19 Aug 2018 18:20:31 EST ID:457vC2+I No.57435 Ignore Report Reply
Almost all meteor showers are annual or cyclical, dood. We aren't here to teach you astronomy, we're here to talk about it.
Roger Penrose - Tue, 09 Oct 2018 05:59:14 EST ID:U4u72hWB No.57464 Ignore Report Reply
if you don't ask they don't have time to tell.
Wilhelm Beer - Thu, 15 Nov 2018 04:28:30 EST ID:N7xCPuZj No.57491 Ignore Report Reply
Leonid shower's s'pposed to be coming up this weekend, for those who won't have a big honkin' snowstorm gumming up the skies, at least.

/STEM/ Ignore Report View Thread Reply
Arthur Eddington - Thu, 01 Nov 2018 23:18:58 EST ID:7ez/W0kB No.57485
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Slow board, maybe we should have /stem/
Subramanyan Chandrasekhar - Fri, 02 Nov 2018 03:15:02 EST ID:m8u2eXUq No.57486 Ignore Report Reply
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Everyone is planning a space party lately

Maybe they need more time to planet.

duuuuuude Ignore Report View Thread Reply
Galileo Galilei - Thu, 01 Nov 2018 22:59:06 EST ID:6fcUdTGI No.57484
File: 1541127546853.jpg -(256320B / 250.31KB, 1280x1281) Thumbnail displayed, click image for full size. 256320
see that spherical black shit under the gas? that the event horizon. not actually a thing but a region where even light falls in. that bubble isn't even contorned by gas but the gas's glow stretches in a sphere because of gravity tides.
this shit is awesome that's what it is

Dark Matter and GR - struggling to understand Ignore Report View Thread Reply
Bart Bok - Sun, 30 Sep 2018 09:15:14 EST ID:9RKOIT3O No.57458
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Hey there fellow egghead stoners. Would you be able to guide me through this?

So, the whole concept of dark matter and energy. I find it a little dubious, I take it this hasn't been confirmed in any way - rather, like many theories in physics has been introduced as an attempted explanation of mismatch between empirical data and theoretical predictions.

But this is just an impression I've got from the superficial knowledge of modern physics I've got, so I'd rather first understand the basis for this hypothesis better before judging it dubious.

So the way I understand it is the concept was proposed in 30s to explain the observed movement of galaxies, in particular why some stay in clusters rather than be launched off due to the acquired speed.

So it is inferred that there must be enough gravity force to keep them together instead. This begs the first question: what is the expected mass calculation based on? As in, how'd they go about measuring that?

But all right, aside from that bit I'm missing, assume the mass predictions are sound. In Newtonian mechanics - so far so good. But now if we introduce GR we allow the concept of black holes which would escape our observations. Why does that not account for 'dark matter' effect? It fits the criteria of (1) great mass (2) inability to be observed

So the way this is taken into account, I understand, that all right - there may be black holes which we cannot observe, but we still have a rough prediction on their mass which we infer from gravitational lensing - and that is way not enough to account for 'dark matter', and hence the concept remains valid.

My questions to you anons:
1) Is the line of reasoning above more or less sound
2) Any resources on the subject to recommend which would explain in bit more detail how the calculations made? (seems like internet is full of pseudoscience articles but I can't seem to easily google a decent source)
3) Could it be possible that inferring
i) mass bends spacetime
ii) spacetime is observed to be bent
iii) therefore there must be mass
is wrong, because mass may not be the only reason the spacetime is bent. That is, could it be that the 'dark matter effect' is not due to some exotic type of matter, but rather an innate (or otherwise not yet understood by our science) geometrical feature of spacetime.
Johann Encke - Mon, 01 Oct 2018 01:21:26 EST ID:457vC2+I No.57461 Ignore Report Reply
>> what is the expected mass calculation based on?
Light from main sequence stars. We look at a galaxy, look at it's luminosity to estimate the number of main sequence stars, and estimate mass from that. Almost all galaxies thus have a totally insufficient amount of normal matter to account for their mass (although we have found some galaxies without dark matter, or with hardly anything but dark matter, but this is quite rare) or rather, what their mass would have to be in order for them to maintain coherency.

>> there may be black holes which we cannot observe, but we still have a rough prediction on their mass which we infer from gravitational lensing
You would think we could do this, but in practice we can only use gravitational lensing and other gravitational effects to detect black holes in this way if there is a significant amount of parallax on the black hole (otherwise, unless we are just lucky enough to have a sufficiently bright star in line with it and us along its event horizon, we will simply miss it) for this reason we can use this method to kind of hunt randomly for black holes, we can't use it to estimate how many black holes there actually are -- we have no idea as to the answer to that question, from an empirical standpoint.
>>2) Any resources on the subject to recommend which would explain in bit more detail how the calculations made?
>>iii) therefore there must be mass
I think there are strong reasons to suspect this line of thinking might be flawed, especially since the only reason we describe dark matter as matter is simply because we can't think of anything else to describe it as. Relatively popular but unaccepted are theories that dark matter and energy represent the influence of alternate quantum realities upon our universe, or may otherwise be some sort of shadow of the m-brane. Unfortunately, a long running contender for non-DM/DE explanations, MOND, was recently disqualified due to new observations, although people are seeing if it can be saved with an update.

In short, absolutely it could be something else. DM/DE really is just a placeholder. But that begs the question: what else? We've been scratching our heads on that one for almost a hundred years, and we have uncovered startlingly little.
Fred Hoyle - Sat, 06 Oct 2018 19:23:55 EST ID:8/fKg+Ea No.57462 Ignore Report Reply

Hopefully the James Webb space telescope will be launching under it's most recent date in 2021 and provide us some new insights.

That FTL means time travel meme Ignore Report View Thread Reply
Pierre-Simon Laplace - Sat, 16 Dec 2017 22:22:45 EST ID:hGyQlc1t No.57130
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I have a question regarding this:
If you look at this gif it shows you "backwards" travel:
The first "jump" after the first acceleration points into the direction that corresponds to the lower left quadrant of the previous reference frame leading to backwards time travel.
However: Drawing it into the upper right quadrant should be equally legal which would imply forward time travel. This would imply that direction you are moving in space would dictate the direction of the "time travel" which seems entirely non-sensical to me.
I guess this is also the point but I still get the feeling I'm missing something here.
20 posts and 3 images omitted. Click View Thread to read.
Bernard-Ferdinand Lyot - Thu, 27 Sep 2018 18:55:44 EST ID:3nlPOKZc No.57456 Ignore Report Reply
Bart Bok - Sun, 30 Sep 2018 09:42:04 EST ID:9RKOIT3O No.57459 Ignore Report Reply
>However: Drawing it into the upper right quadrant should be equally legal
Equally illegal? ;)

>This would imply that direction you are moving in space would dictate the direction of the "time travel" which seems entirely non-sensical to me.
These diagrams are entirely symmetrical in terms of all dimensions, as in choice of 'left' and 'right' just as 'up' and 'down' is arbitrary

I feel there is an ambiguity in what constitutes time travel. As in, the intuition we typically may have about this being '2018-09-30' -> '2008-09-30' same place.

But in terms of general relativity, any travel with speed >c is time travel. This is called moving in a 'timelike curve' in 4D spacetime - as opposed to 'spacelike curves' which we (and all we know) typically move on. On the GIF all curves within yellow area are spacelike and blue area timelike.

So for example if you 'teleported' a light year away from your current whereabouts, that'd be considered time travel. Because if you send a light signal to earth, and teleport back - you will not see it for another year. So you influenced the future without exactly 'changing' the date on your calendar

Mind you if you simply travel half a year back/forward keeping your position fixed, you'd arrive in some different place because likely the earth, sun and entire galaxy would've moved away.
Bart Bok - Sun, 30 Sep 2018 09:55:02 EST ID:9RKOIT3O No.57460 Ignore Report Reply
or maybe better example:
  1. you travel a year back in time from now to 2017
  2. you end up a light year away from initial position
  3. 2017 you wants to send stock market results to 2018 you
  4. at best 2017 you will be able to send them with speed of light
  5. light takes a year to arrive to 2018
  6. in that case, the information you're sending arrives in 2018 and you haven't actually managed to send it back in time, because it still has to make up for the distance before it reaches you

if you change space distance from 1 light year away to 0.5 light year away however, you will be able to send information to 'past you' (with speed of light) so it arrives mid-2017 (and either you're filthy rich or paradoxically disappear hehehe)

Interchan Warning System Ignore Report View Thread Reply
Maximilian Wolf - Fri, 28 Sep 2018 00:48:46 EST ID:9ugkcJUP No.57457
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***End of message***
Bernhard Schmidt - Thu, 15 Nov 2018 20:29:27 EST ID:rNBxnMOH No.57496 Ignore Report Reply
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All weebs should be shot nb

fate of universe Ignore Report View Thread Reply
Jocelyn Bell - Sun, 14 Sep 2014 23:31:05 EST ID:SknUZfy5 No.54393
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Is there a theory that says that eventually the universe will expand so large that it will collapse in on itself and create another big bang?

What are your thoughts on the fate of the universe?

"The Last Question" by Isaac Asimov is a short story about the fate of mankind and the universe. Idk if everyone on this has read it or not, but I love it. Here's the link: http://www.multivax.com/last_question.html
44 posts and 6 images omitted. Click View Thread to read.
Charles Messier - Tue, 04 Sep 2018 11:45:13 EST ID:457vC2+I No.57444 Ignore Report Reply
I'll help Lemaitre out by saying the first two statements are uncontroversial possibilities thoroughly discussed ITT. The first is the Big Freeze, Heat Death, leading to a Big Rip: https://en.wikipedia.org/wiki/Big_Rip
The second is the Big Crunch, which is now thought to be impossible under current observations but was popular in the 20th C.: https://en.wikipedia.org/wiki/Big_Crunch

As for the third I have no idea what he's alluding to and I'm really interested also.
Johannes Kepler - Sat, 22 Sep 2018 19:46:39 EST ID:kahFeNFq No.57452 Ignore Report Reply
>Woah what? Who thinks that?
people trying to unify quantum mechanics and general relativity into a single theory

do you try to quantize gravity or do you try to gravitize quanta?
do you treat quantum entanglement as tiny wormhole?
do you treat blackhole as the entropy surface?
could geometry of space be determined by level of entanglement in quantum foam in a region of space?
could dimensionality of space be an emergent property of quantum mechanics?

>I know relating the the dimensions of space is that one that suggested that 3 dimensions of space and 1 of time was the only logically possible one, that all other kinds of universes would be literally impossible. I don't agree with that idea but it seems like people have given up on making a rigorous theory of the relationship between the dimensions (or assume GR's spacetime covers it.)

try incorporate probabilities into dimensions of space

does the "literally impossible" part come from encountering infinity and divide by zero with utilizing earlier understanding of mathematics?
Chushiro Hayashi - Sun, 23 Sep 2018 00:01:29 EST ID:457vC2+I No.57453 Ignore Report Reply
>>does the "literally impossible" part come from encountering infinity and divide by zero with utilizing earlier understanding of mathematics?
Perhaps, it is more like the image suggests; it's a suggestion about the topology of spacetime and whether causality or space could be consistent with that number of dimensions. However, it's equally likely that all those other possible coordinates could also have universes like ours, in which the mathematics equally suggest that only their dimensional composition is possible and all others impossible.

How does a closed Ignore Report View Thread Reply
jolinar - Mon, 16 Jul 2018 20:31:55 EST ID:4+cG6NBX No.57348
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Timeline curve work? Could you be trapped in it forever ?
I have a writing prompt
Stephen Hawking - Tue, 17 Jul 2018 00:04:28 EST ID:457vC2+I No.57349 Ignore Report Reply
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Closed timelike curves are totally theoretical objects -- we have no real information about how they would work, or if they are even possible. Essentially, what is 'curved' in a CTC is the 'geodesic' of spacetime. What this means that, for example, if you had a geodesic curvature in space at a 45 degree angle and you fired a laser beam into that space, as it entered it the beam within it would appear to you (if you could see it reflected) as if it had bent at that same angle even though it encountered no object. In a 'closed' timelike curve, remembering that space and time are a continuum, if the curvature is so extreme that it forms a torus, i.e. loops back on itself, and one traversed the distortion in the (normally flat i.e. euclidean) curved spacetime, one could end up at the end of passing through the distortion at the same point in space, but an earlier point in time.

If you were stuck on it would depend on how you got into such an unusual object in the first place. If the geodesic torus could only be made so small, so that in order to traverse it one had to travel at relativistic speeds, the degree of time distortion could be amplified. Also, it's possible that actual matter (rather than energy) trapped within a CTC could become inertially unbound, so there might be no way to stop a spacecraft (for example) that was travelling through one, trapping its crew on an eternal voyage into the past (or future, depending on the 'direction' the geodesic is distorted in the fourth dimension.)

Anyway, a lot of people will not see any time travel story as 'hard sci-fi' so you probably have a lot of leeway. Hawking famously believed that a CTC would destroy itself in a cosmological version of the grandfather paradox, as heat from the torus' relative future would propagate backwards in time, eventually creating a thermal singularity that would destroy it.
Vesto Slipher - Thu, 13 Sep 2018 15:52:54 EST ID:BJSneKKV No.57445 Ignore Report Reply
I’ve seen it trapped forever
Annie Cannon - Sat, 15 Sep 2018 13:46:07 EST ID:yzfSDg8q No.57446 Ignore Report Reply
Theoretically, you cease to exist in the timestream as soon as you get in the box, while your time-travelling double (who left the box at some point in the past) continues along the timestream as normal and never gets back in the box. In theory.

moon Ignore Report View Thread Reply
Jocelyn Bell - Thu, 31 May 2018 10:35:24 EST ID:HhkM3rED No.57285
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Does the moon really have influence on behavior? Or is it a well loved myth?
13 posts and 4 images omitted. Click View Thread to read.
Stephen Hawking - Tue, 17 Jul 2018 00:22:10 EST ID:457vC2+I No.57350 Ignore Report Reply
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I think I'll play it safe and leave it at that for here. Took the meta topic (of skeptical illuminism) to /spooky/ like you suggested, to expand it a bit beyond simply astrology. See ya there anyone who is still interested!
Jericho !.iRAtomic2 - Wed, 22 Aug 2018 00:13:41 EST ID:qgHixtEA No.57436 Report Reply
So, as a general skeptic of anything that can't be scientifically proven, I never actually believed in this.

Until I started working with people with developmental disabilities.

For whatever reason, the day after full moons, behaviors in clients would spike drastically. Most of the times that I was attacked, bitten, had my hair pulled, was the first day after a full moon. My personal belief was that this may simply be a function of the increased amount of light at night, with my reasoning being that it kept people up more at night, especially those who were sensory sensitive. As irritability is a common side effect of lack of sleep, this would lead to clients being more sensitive to stimuli that might upset them. Obviously, this is all anecdotal, but I think it deserves to be said. I actually have data on attacks and behaviors from one client who required close recordkeeping, but have yet to compare this data to full moons. However, I do know that at least a few times, the night was completely overcast. Perhaps enough light filters through the clouds to support my theory of light interfering with sleep, but I really couldn't say without having actually measured the amount of moonlight on a nightly basis. And if it was solely a question of light, why didn't these behaviors occur in a smooth curve as the moon waxed and waned, instead of tending to occur all at once, the day after the full moon?

I really don't know. I wish I had answers, because it would have helped me out a lot in my last job.
Edmond Halley - Wed, 22 Aug 2018 15:08:12 EST ID:457vC2+I No.57437 Ignore Report Reply
How could it really be the light though, since humans have been exposed to a huge amount of additional light thanks to artificial lighting and no one has gone crazy? There would have to be something special about light coming from the moon, which is even a more woo-woo direction to go in that assuming it has something to do with the tides or magnetism.

Lakes of liquid water found on Mars Ignore Report View Thread Reply
Caroline Herschel - Thu, 26 Jul 2018 15:44:03 EST ID:CZNpyEE2 No.57358
File: 1532634243590.jpg -(3262171B / 3.11MB, 5333x3333) Thumbnail displayed, click image for full size. 3262171
Ground-penetrating radar images of the southern polar cap of Mars taken by ESA's Mars Express suggest the presence of liquid water 1.5 km beneath the surface. As pure liquid water probably cannot exist at such a shallow depth and low temperature, the research team posits that the water is a brine with salts and perchlorates that dramatically lower its freezing point. The largest discovered aquifer is 20 km wide, but its thickness cannot be accurately estimated. The water reservoirs would take the form of salty brine pools beneath the mile of layered ice and dust, or the water might be a component of thicker brine-dirt sludge, mixed with Martian regolith.


Astronomical data Ignore Report View Thread Reply
James Randi - Fri, 29 Jun 2018 13:36:57 EST ID:BPHCgbLm No.57327
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I had an idea to build a digital astronomical clock for fun in unity as a learning exercise. It would include solar system clock showing the "time" and such on various planets and a 3rd model of the solar system.
I'd like to try aim for a bit of realism and have the models of planets be in accurate locations to real life.
What would be the best source for finding out planet locations so that they don't all start in the 12 oclock position when I start my program?
Like if I added Mars, how do I find how far into its solar year (month?) It currently is on Mars?

I'm new to coding in general, I already have the data for earth but that's done simply by telling the program to check the system clock and moves the model of earth to right orientation.
6 posts omitted. Click View Thread to read.
James Randi - Fri, 06 Jul 2018 20:46:11 EST ID:CxvjOUYt No.57340 Ignore Report Reply
any links to some sort of table would be helpful too
Urbain Le Verrier - Sat, 21 Jul 2018 13:39:49 EST ID:hGyQlc1t No.57355 Ignore Report Reply
they mention:
digging a little there is also this:
which leads to this
Urbain Le Verrier - Sat, 21 Jul 2018 13:51:43 EST ID:hGyQlc1t No.57356 Ignore Report Reply
Digging a little lets me realize that using that python api would be massive overkill
The table you want is here:
or to precise in this pdf document:

images Ignore Report View Thread Reply
Bruon Rossi - Fri, 29 Jun 2018 11:49:29 EST ID:vxFcQ9yD No.57323
File: 1530287369168.jpg -(3086272B / 2.94MB, 7680x4320) Thumbnail displayed, click image for full size. 3086272
Since this is an imageboard, let's post space related images.
1 posts and 1 images omitted. Click View Thread to read.
Bruon Rossi - Fri, 29 Jun 2018 11:52:42 EST ID:vxFcQ9yD No.57325 Ignore Report Reply
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Bruon Rossi - Fri, 29 Jun 2018 11:56:12 EST ID:vxFcQ9yD No.57326 Ignore Report Reply
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Vera Rubiin - Sat, 07 Jul 2018 18:30:41 EST ID:fjAVn7KX No.57341 Ignore Report Reply
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