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Harm Reduction Notes for the COVID-19 Pandemic


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- Thu, 01 Nov 2018 23:18:58 EST 7ez/W0kB No.57485
File: 1541128738303.jpg -(4349B / 4.25KB, 300x168) Thumbnail displayed, click image for full size. /STEM/
Slow board, maybe we should have /stem/
Subramanyan Chandrasekhar - Fri, 02 Nov 2018 03:15:02 EST m8u2eXUq No.57486 Reply
1541142902535.jpg -(56782B / 55.45KB, 720x638) Thumbnail displayed, click image for full size.
Everyone is planning a space party lately

Maybe they need more time to planet.


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- Thu, 01 Nov 2018 22:59:06 EST 6fcUdTGI No.57484
File: 1541127546853.jpg -(256320B / 250.31KB, 1280x1281) Thumbnail displayed, click image for full size. duuuuuude
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

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- Sun, 30 Sep 2018 09:15:14 EST 9RKOIT3O No.57458
File: 1538313314587.jpg -(134701B / 131.54KB, 835x557) Thumbnail displayed, click image for full size. Dark Matter and GR - struggling to understand
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 457vC2+I No.57461 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 8/fKg+Ea No.57462 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

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- Sat, 16 Dec 2017 22:22:45 EST hGyQlc1t No.57130
File: 1513480965587.gif -(117244B / 114.50KB, 323x402) Thumbnail displayed, click image for full size. That FTL means time travel meme
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.
Bart Bok - Sun, 30 Sep 2018 09:42:04 EST 9RKOIT3O No.57459 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 9RKOIT3O No.57460 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

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- Fri, 28 Sep 2018 00:48:46 EST 9ugkcJUP No.57457
File: 1538110126824.jpg -(74637B / 72.89KB, 548x550) Thumbnail displayed, click image for full size. Interchan Warning System


***End of message***
Bernhard Schmidt - Thu, 15 Nov 2018 20:29:27 EST rNBxnMOH No.57496 Reply
1542331767842.jpg -(133179B / 130.06KB, 1280x720) Thumbnail displayed, click image for full size.
All weebs should be shot nb

fate of universe

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- Sun, 14 Sep 2014 23:31:05 EST SknUZfy5 No.54393
File: 1410751865116.jpg -(810494B / 791.50KB, 1400x907) Thumbnail displayed, click image for full size. fate of universe
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
43 posts and 6 images omitted. Click View Thread to read.
Charles Messier - Tue, 04 Sep 2018 11:45:13 EST 457vC2+I No.57444 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 kahFeNFq No.57452 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 457vC2+I No.57453 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

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- Mon, 16 Jul 2018 20:31:55 EST 4+cG6NBX No.57348
File: 1531787515505.jpg -(85295B / 83.30KB, 1125x1111) Thumbnail displayed, click image for full size. How does a closed
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 457vC2+I No.57349 Reply
1531800268505.png -(130973B / 127.90KB, 431x393) Thumbnail displayed, click image for full size.
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.
Annie Cannon - Sat, 15 Sep 2018 13:46:07 EST yzfSDg8q No.57446 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.


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- Thu, 31 May 2018 10:35:24 EST HhkM3rED No.57285
File: 1527777324976.jpg -(2143958B / 2.04MB, 2580x2452) Thumbnail displayed, click image for full size. moon
Does the moon really have influence on behavior? Or is it a well loved myth?
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Stephen Hawking - Tue, 17 Jul 2018 00:22:10 EST 457vC2+I No.57350 Reply
1531801330505.jpg -(174176B / 170.09KB, 754x1070) Thumbnail displayed, click image for full size.
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 qgHixtEA No.57436 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 457vC2+I No.57437 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

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- Thu, 26 Jul 2018 15:44:03 EST CZNpyEE2 No.57358
File: 1532634243590.jpg -(3262171B / 3.11MB, 5333x3333) Thumbnail displayed, click image for full size. Lakes of liquid water found on Mars
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

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- Fri, 29 Jun 2018 13:36:57 EST BPHCgbLm No.57327
File: 1530293817601.jpg -(138469B / 135.22KB, 1200x1200) Thumbnail displayed, click image for full size. Astronomical data
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.
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James Randi - Fri, 06 Jul 2018 20:46:11 EST CxvjOUYt No.57340 Reply
any links to some sort of table would be helpful too


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- Fri, 29 Jun 2018 11:49:29 EST vxFcQ9yD No.57323
File: 1530287369168.jpg -(3086272B / 2.94MB, 7680x4320) Thumbnail displayed, click image for full size. images
Since this is an imageboard, let's post space related images.
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Vera Rubiin - Sat, 07 Jul 2018 18:30:41 EST fjAVn7KX No.57341 Reply
1531002641478.gif -(2398469B / 2.29MB, 640x480) Thumbnail displayed, click image for full size.

Astronomical Illusion - Earth is the center of the universe

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- Tue, 19 Jun 2018 17:15:11 EST 6aIwEr35 No.57311
File: 1529442911009.jpg -(342372B / 334.35KB, 1920x1080) Thumbnail displayed, click image for full size. Astronomical Illusion - Earth is the center of the universe

This is from a video series I saw long ago and it described a general illusion that is responsible for the Earth being seen as the center of the universe.

Like they say that in a few million/billion years the sky is going to be completely dark because the stars are moving away from us. But this is just an illusion from our vantage point. We're also moving away from them but we can't see it, only visualize it.

The way I remembered in the video was very clever and simple.

It was like rows and columns of 4 dots:

. . . .
. . . .
. . . .
. . . .

And it had like a clear paper with one dot in the middle. And as the transparent paper moved, the dot moved relative to the stationary background and you could see how the center of the dot in the transparent paper stayed stationary as the rest moved away.

I'm probably not explaining it right because even that doesn't make sense to me but maybe it's enough to go on for one of you out there
1 posts omitted. Click View Thread to read.
Thomas Henderson - Wed, 20 Jun 2018 10:08:09 EST 6aIwEr35 No.57313 Reply

Thanks for the explanation but the illusion I was referring to was the fact that astronomers before would always postulate that Earth was the center of everything (that is, stationary) and everything else is moving away or moving around us.

But in reality, Earth is moving as well and isn't actually stationary.

The illusion is that Earth is just used as a stationary anchor point for our perspective because we need a relatively stable point to base our calculations on. Like the same way we arbitrarily chose the weigh of a kilogram and now use that to conceptualize weight relative to one another.

But because of modern technology, we can visualize the universe more conceptually without putting Earth at the center.
Henry Draper - Wed, 20 Jun 2018 22:42:36 EST 457vC2+I No.57314 Reply
1529548956888.jpg -(111795B / 109.17KB, 1280x720) Thumbnail displayed, click image for full size.
Astronomers certainly are aware of the motion of our solar system and account for it in their calculations when it is relevant, including calculations of expansion and redshift. I agree I wish popularly available star charts included depictions of the direction of motion and speed of stars so people can visualize what is going on better, but if, as a matter of principle, we stop using earth as the reference point, over time they will become off center with the physical hubble volume, the universe-lifetime light sphere of earth, which is obviously centered here. Once we are an interplanetary species, we will obviously need new definitions, and for most practical purposes the difference won't matter much.

How would you feel about using the center of the galaxy (either its gravitational center or the supermassive blackhole Sag A*) as our reference center point? That wouldn't differ too much from our visible observations, and seems the most convenient.
Annie Cannon - Wed, 27 Jun 2018 15:30:26 EST 6aIwEr35 No.57319 Reply

I'm not against using Earth or whatever as a reference.

I was just intrigued by the natural phenomena that we see ourselves as the center of things when it's a fallacy of perception. And I remember the same phenomena existed in astronomy until the copernican revolution


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- Fri, 25 May 2018 04:39:48 EST eiFhhu/4 No.57283
File: 1527237588460.jpg -(368926B / 360.28KB, 720x1280) Thumbnail displayed, click image for full size. Hey
Check this mother ****** out.
Kiyotsugu Hirayama - Sat, 26 May 2018 13:15:33 EST 10X7g+Qi No.57284 Reply
1527354933221.jpg -(2595730B / 2.48MB, 2448x3264) Thumbnail displayed, click image for full size.
Whoay thread. I'm going to be working all day and maybe into the night. Hope i produce something increadible!

Stephen Hawking died at age 76

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- Wed, 14 Mar 2018 03:52:46 EST UgaLEhyB No.57237
File: 1521013966541.jpg -(203302B / 198.54KB, 1160x629) Thumbnail displayed, click image for full size. Stephen Hawking died at age 76
Goodnight you genius retard
William Hartmann - Wed, 14 Mar 2018 09:04:12 EST eygzYfFg No.57238 Reply
His absurd in-mental astrophysics simulations will be missed. Rest in peace dude, you deserve it.
Thomas Henderson - Wed, 14 Mar 2018 11:22:05 EST sL8p9E02 No.57239 Reply
RIP to the coolest dude.
William Fowler - Fri, 13 Apr 2018 19:43:23 EST Iarb3bdT No.57277 Reply
You were a remote-controlled animatronic silicone muppet for decades, but a pretty good mascot and an excellent rapper.

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