Talk:2853: Redshift

2023-11-12T14:31:04Z

172.71.155.20: closed-form solution to integral, 27 times faster

Does it make any sense to try and relate the two Z values to a more "normal" time? [[User:MAP|MAP]] ([[User talk:MAP|talk]]) 21:08, 10 November 2023 (UTC)

I have added exactly that, using `astropy.cosmology` for the calculations [[User:Juandesant|Juandesant]] ([[User talk:Juandesant|talk]]) 21:16, 10 November 2023 (UTC)

There is a big error in the current explanation, saying it means they were interested in this since the early universe, but that would only be true if the z value was much closer to 1. I'm not exactly sure as I haven't done the math, but with that many decimal places of zero's it is probably near enough history to be during their lifetime. So the joke isn't being interested in the early universe since the early universe, but rather so interested in it that they talk about other things with the same terminology.--[[Special:Contributions/172.70.126.142|172.70.126.142]] 21:18, 10 November 2023 (UTC)

Why aren't these values expressed in scientific notation? Separately, do they make sense logarithmically? [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 07:12, 11 November 2023 (UTC)
:Part of the joke is that the values are unwieldy to use compared to everyday language and units. The scientific notation would have lessened this. However they are given in a universal standard time instead of some solar system or human related units, so they generally should be clearly preferred. Sebastian --[[Special:Contributions/172.68.110.188|172.68.110.188]] 15:37, 11 November 2023 (UTC)

I feel like the Earth's gravitational field would affect the answer as z goes to zero? [[Special:Contributions/172.69.22.210|172.69.22.210]] 06:57, 12 November 2023 (UTC)

== Calculation ==

Thanks to ChatGPT-4 and the [https://code.google.com/archive/p/cosmonom/downloads Fortran-90 code] from [https://arxiv.org/pdf/1303.5961.pdf arxiv:1303.5961 (which please see, it's really cool)] here's how to get the look-back time from redshift in Python:

<tt><pre><nowiki>
from scipy.special import hyp2f1 # hypergeometric function is in integral solution
from numpy import format_float_positional # to avoid scientific notation formatting

# Cosmological parameters from the Fortran params.f90 header
#H0 = 67.15 # Hubble parameter in km/s/Mpc (or, 73.5: the "crisis in cosmology")
H0 = 69.32 # from Explainxkcd for 2853: Redshift; seems a consensus compromise
OL = 0.683 # Density parameter for dark energy
Om = 0.317 # Density parameter for matter

# Age of universe at redshift z as a closed-form solution to integral, which...
def age_at_z(z): # ...is 27 times faster than the original numeric integration.
hypergeom = hyp2f1(0.5, 0.5, 1.5, -OL / (Om * (z + 1)**3))
return (2/3) * hypergeom / (Om**0.5 * (z + 1)**1.5) * (977.8 / H0)

# Current age of the universe at redshift 0 in Gyr
age0 = age_at_z(0)

# Function to calculate the look-back time at redshift z in Gyr
def zt(z): # from the function name in the Fortran cosmonom.f90 code
return age0 - age_at_z(z)

# For z = 0.00000000038
z1 = 0.00000000038
look_back_time_years_z1 = zt(z1) * 1e9 # from Gyr to years
print("Look-back time for z=" +
f"{format_float_positional(z1)}: {look_back_time_years_z1:.1f} years")

# For z = -0.000000000000045
z2 = -0.000000000000045
look_back_time_hours_z2 = zt(z2) * 1e9 * 365.25 * 24
print("Look-back time for z=" +
f"{format_float_positional(z2)}: {look_back_time_hours_z2:.1f} hours")
</nowiki></pre></tt>

The output being:

<tt><pre><nowiki>
Look-back time for z=0.00000000038: 5.4 years
Look-back time for z=-0.000000000000045: -5.5 hours
</nowiki></pre></tt>

And should you wish to make [https://i.ibb.co/MnSGrc7/time-by-redshift-new.png this quick reference chart for interpreting observations in the JWST era:]

<tt><pre><nowiki>
import matplotlib.pyplot as plt

redshifts = [z * 20 / 299 for z in range(300)] # 300 steps, 0 to 20
look_back_times = [zt(z) for z in redshifts]

plt.plot(redshifts, look_back_times)
plt.title('Look-back Time by Redshift')
plt.xlabel('z')
plt.ylabel('Billion Years Ago')
plt.xticks(range(21))
plt.yticks(range(15))
plt.grid(True, color='lightgray')

for t in range(0,13):
z = redshifts[min(range(len(look_back_times)),
key=lambda i: abs(look_back_times[i]-t))]
plt.text(z, t, f" z = {z:.2f}", ha='left', va='center')

for z in range(6,21,2):
t = zt(z)
plt.text(z, t, f"{t:.2f}", ha='center', va='bottom')

plt.savefig('time_by_redshift_new.png', bbox_inches='tight')
</nowiki></pre></tt>

[[Special:Contributions/172.69.22.12|172.69.22.12]] 08:50, 12 November 2023 (UTC)

Talk:792: Password Reuse

2023-09-21T06:11:46Z

172.71.155.20: Happy birthday to Abe

And now it turns out that Google gives our data to NSA....sigh. [[Special:Contributions/24.7.241.154|24.7.241.154]] 07:58, 11 June 2013 (UTC)Monica

What happened in March of 1997? [[User:MR|MR]] ([[User talk:MR|talk]]) 18:23, 4 April 2013 (UTC)MR

Hi! After consulting Wikipedia's article about March 1997 (http://en.wikipedia.org/wiki/1997), I think there are two main incidents Black Hat could refer to:
*The '''Phoenix Lights''', a group of supposed UFOs, turned out to be probably military aircrafts.
*The mass suicide committed by 39 '''Heaven's Gate''' cultists.
Since we know little about Black Hat's life in 1997, we could argue that he was expecting an extra-terrestrial contact or that he was attracted by the ideas of that creed - and that the disillusion brought him his present disbelief in things.
Of course those are just hypotheses, and don't seem to fit the character as we know him...[[User:Inverno1407|Inverno1407]] ([[User talk:Inverno1407|talk]]) 11:30, 15 April 2013 (UTC)
:I honestly believe that he created the Heaven's Gate cult and he views their mass suicide as his crowning achievement in getting people to believe things, it just isn't getting any better than that, so he doesn't believe in anything anymore. [[Special:Contributions/173.245.54.32|173.245.54.32]] 13:03, 30 October 2015 (UTC)

----
:<br />
:"In the conclusion, Black Hat reveals that the only thing he's doing with all his hacked user accounts is to post slightly inaccurate content on Wiki sites."

This paragraph has been present since this explanation was added. I can't see how it is arrived at from the comic. <small>(So I wonder who [[User:148.87.67.212]] might have been...)</small> [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 14:10, 15 April 2013 (UTC)

I removed some slightly inaccurate content from this wiki. It was the bit about Black Hat posting slightly inaccurate content on wiki sites.[[Special:Contributions/86.40.93.217|86.40.93.217]] 00:33, 15 May 2013 (UTC)

Does anyone know if he had anything to do with the article on "taking the piss"?

[[User:Weatherlawyer| I used Google News BEFORE it was clickbait]] ([[User talk:Weatherlawyer|talk]]) 16:10, 26 January 2015 (UTC)
----
How does this compare in light of [[792:_Password_Reuse|792:Password Reuse]]? [[User:Saibot84|Saibot84]] ([[User talk:Saibot84|talk]]) 05:06, 6 June 2013 (UTC)

The "March 1997" issue is still a mystery to me. May be a global computer virus attack? I will go through all days on wikipedia. The month summery presents not the solution.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 17:27, 6 June 2013 (UTC)

Conisdering how blackhat loves messing with people, I seriously doubt anything at all hapened in March 1997. He's just messing with us! [[Special:Contributions/189.5.106.228|189.5.106.228]] 02:43, 7 July 2013 (UTC)

Oooo, I dunno. Given Black Hat's odd tastes, *anything* from March 1997 could have caused him to lose his faith: Paul McCartney being knighted, Tom Cruise winning an Oscar, the U.S. Supreme Court hearing arguments on Internet Indecency, India's Ministry of Charity choosing a successor to Mother Theresa, Gene Roddenberry's ashes going into orbit, the Brazil Senate finally allowing women members to wear slacks... Anything!! [[http://www.historyorb.com/events/date/1997/march]]
:Wow, look at this historical CNN page: [http://edition.cnn.com/ALLPOLITICS/1997/03/19/scotus.cda/ http://edition.cnn.com/ALLPOLITICS/1997/03/19/scotus.cda/]. The {{w|Communications Decency Act}} is the most likely item from your list.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 08:21, 2 August 2013 (UTC)
::39 Heaven's Gate cultists committed mass suicide
::If he was upset at causing their deaths or having accomplished their deaths, has little to prove now nor reason to repeat the act, he is on pause; we wait.
::[[User:Weatherlawyer| I used Google News BEFORE it was clickbait]] ([[User talk:Weatherlawyer|talk]]) 16:10, 26 January 2015 (UTC)
:::I would say that he lostall belief in his sadistic powers when tthese cultists killed themselves: People kill themselves without any need of his evil scheming, and he obviously expect himself to be the pinnacle of that. That event is pretty much showing him that he is simply not needed. [[Special:Contributions/172.70.250.189|172.70.250.189]] 08:21, 23 July 2023 (UTC)
----
My opinion is that Black Hat referred to Bill Clinton banning federal funding for research on human cloning in March 1997.{{unsigned ip|108.162.242.5}}
:How would that create an hiatus in Back Hat's career?

[[User:Weatherlawyer| I used Google News BEFORE it was clickbait]] ([[User talk:Weatherlawyer|talk]]) 16:10, 26 January 2015 (UTC)

Hey! I though I'd throw in the opinion that perhaps March 1997 was a month of personal importance to Black Hat rather than anything societal. If the 1997 coincides with any of those standard "loss of idealism and innocence years" for Black Hat, then I'd say that's pretty likely what Randall was going for. {{unsigned ip|108.162.216.209}}

Hi - the last line about the TV show DIBS is wrong. DIBS came out in 2014 - the comic in 2010. What the last panel is referring to is calling dibs on the TV to play CoD4. {{unsigned ip|108.162.218.53}}

== Google's "don't be evil" is no more ==

Google removed that "don't be evil" thing from their motto...

*password change intensifies*

[[Special:Contributions/172.68.10.172|172.68.10.172]] 06:35, 5 July 2019 (UTC)

[https://tvtropes.org/pmwiki/pmwiki.php/UnintentionalPeriodPiece/SpecialCases TV Tropes links to this comic as an example of one of the strips that have aged the worst.] [[User:LendriMujina|LendriMujina]] ([[User talk:LendriMujina|talk]]) 19:16, 28 January 2022 (UTC)

As of 2022 as I write, Google has now set itself up to be the password manager for random non-Google web sites, so they have many peoples' credentials. Of course, Microsoft followed their usual practice and did the same thing, but not quite as seamlessly. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 11:55, 8 May 2022 (UTC)

As for human cloning, if we are really gonna do this, we should start with cloning one of the former premiers, such as Abe (today is his birthday). [[Special:Contributions/172.71.155.20|172.71.155.20]] 06:11, 21 September 2023 (UTC)

explain xkcd - User contributions [en]

Talk:2853: Redshift

Talk:792: Password Reuse