First public show.

universe-from-nothing/annex-events.ms

@@ -195,22 +195,21 @@ move to CIRCULAR_DIFFRACTION_FIGURE + (0, -1)
 
 
 .\" Exponential: oldvalue + growth factor -> newvalue
-.G1
-GROWTHFACTOR=0.07
-
-frame ht 2.5 wid 2.8
-define expo { $1+$1*GROWTHFACTOR }
-value = 1
-draw LINEAR solid
-for i from 1 to 100 by 1 do {
-  next LINEAR at i, i
-  times at i, value
-  value = expo(value);
-}
-line from 0,650 to 3,650
-"    linear curve" ljust at 1,650
-"    exponential curve" ljust at 1,600
-times at 1,600
-label top "Exponential curves: growth over time (7%)" up .2
-.G2
-
+.\" .G1
+.\" GROWTHFACTOR=0.07
+.\" 
+.\" frame ht 2.5 wid 2.8
+.\" define expo { $1+$1*GROWTHFACTOR }
+.\" value = 1
+.\" draw LINEAR solid
+.\" for i from 1 to 100 by 1 do {
+.\"   next LINEAR at i, i
+.\"   times at i, value
+.\"   value = expo(value);
+.\" }
+.\" line from 0,650 to 3,650
+.\" "    linear curve" ljust at 1,650
+.\" "    exponential curve" ljust at 1,600
+.\" times at 1,600
+.\" label top "Exponential curves: growth over time (7%)" up .2
+.\" .G2

universe-from-nothing/ch2_a-cosmic-mystery-story_weighing-the-universe.ms

@@ -2,13 +2,15 @@
 a cosmic mystery story: weighing the universe
 .PP
 .METAINFO1
-Work in progress.
-.METAINFO2
-
-.METAINFO1
-This chapter is about the knowlegde and thought the scientific community had up to the 1980s.
+This chapter presents the thoughts of the scientific community while unravelling some mysteries about our universe.
+This includes how galaxies and clusters of galaxies are working, dark matter, gravity, nature of matter in our universe, etc.
+This chapter also is about the excitment felt by L. Krauss as a young scientist, and his perspectives in the 1980s.
+Finally, the chapter describes how a picture of a 5 billion light-years away galaxy tells us about the distribution of mass within a cluster of galaxies (and
+.B "how our universe will end" ,
+probably).
 .METAINFO2
 
+.ft R
 .QUESTION "How will the Universe end?"
 Since the Universe isn't static, there are three main possibilities.
 The first one is the
@@ -18,8 +20,11 @@ In the second case the Universe will
 .B almost
 stop expanding.
 Last possibility, the Universe will continue to expand at a finite rate.
-To know the answer, 
-
+To answer this question, we use the theory of general relativity and we need to know the total mass of the universe.
+.
+.SH
+First, the nature of the universe
+.PP
 Gravity shapes solar systems as well as galaxies and
 .I clusters
 of galaxies.
@@ -44,7 +49,10 @@ cannot be only made of neutrons and protons.
 .EXPLANATION1
 The Universe is mostly made of matter we don't understand.
 .EXPLANATION2
-
+.
+.SH
+Identifying this dark matter
+.PP
 Maybe this dark matter is made of a particle that can be identified through calculations or educated guess for example.
 This way, new experiments could be proposed to detect this dark matter, and learn more on what appears to be the main component of the universe.
 Later, to that end, we built machines on Earth to recreate an environment where these particles could be created (see the
@@ -66,7 +74,10 @@ In both cases: the chapter doesn't include an explanation of what these
 could be.
 That's kind of a bummer.
 .FOOTNOTE2
-
+.
+.SH
+More about general relativity
+.PP
 .\" .CITATION1
 .\" If these particles were created in the Big Bang, like the light elements (hydrogen, helium and lithium), then we should be able to use ideas about the forces that govern the interactions of elementary particles (instead of the interactions of nuclei relevant to determine elemental abundance) to estimate the abundance of possible exotic new particles in the universe today.
 .\" .CITATION2
@@ -93,9 +104,17 @@ universe.
 The universe will continue to expand at a finite rate.
 Finally, the
 .I flat
-universe, which expands but slow down with time without ever stopping.
+universe, which expands but slows down with time without ever stopping.
 This requires the "dark matter" to be 100 times more massive than visible matter.
-
+.FOOTNOTE1
+TODO: the difference between Big Crunch, flat and open isn't clear
+.B "at all" .
+This probably needs some polishing.
+.FOOTNOTE2
+.
+.SH
+Back to the main track: weighting the universe
+.LP
 .QUESTION "How to get the density of mass in the universe?"
 The largest gravitationally bound objects are
 .I "superclusters of galaxies"
@@ -113,7 +132,8 @@ Therefore, the speed of galaxies in a cluster can be some sort of metric to esti
 
 .METAINFO1
 Note: at the time, little was known of black holes, red dwarves, neutron stars, etc.
-A good chunck of the missing mass actually comes from these objects, with little to no light emissions.
+A good chunk of the missing mass actually comes from these objects, with little to no light emissions.
+And some emissions are infrared, which isn't easily visible on Earth, so we waited orbital telescopes to observe them.
 .METAINFO2
 
 In 1998, the physicist Tony Tyson shows that the mass of a cluster mostly comes from between the galaxies.
@@ -124,10 +144,12 @@ From what is actually written in the book, this seems almost like an exhaustive
 An evolutionary algorithm maybe?
 Too bad there isn't much details: Krauss said the model was based on general relativity but the actual algorithm (to some extent) could have been interesting to learn.
 .FOOTNOTE2
-Finally, once the model produced an image like the one the observation, the model was used to determine the mass of the cluster.
+Finally, once the model produced an image matching the observation, the model was used to determine the mass of the cluster.
 The result was, as stated before, that the mass of the cluster mostly comes from between the galaxies, not from stars or hot gases.
 More precisely: there is 40 times more mass between the galaxies than within, which is 300 times more mass than within stars alone with the rest of visible matter in hot gas around them.
-
+.SH
+More on dark matter
+.LP
 .CITATION1
 [...] more recent observations from other areas of astronomy have confirmed that the total amount of dark matter in galaxies and clusters is far in excess of that allowed by the calculations of Big Bang nucleosynthesis.
 Dark matter must be made of something that isn't normally on Earth nor in stars.
@@ -147,12 +169,29 @@ Direct observation is not necessary, an imbalance between the energy used to sma
 
 .METAINFO1
 The book is from 2009, since then the LXC actually produced results.
-However, as the time of this writting (october 2021), still no direct confirmation that dark matter actually exist.
+However, at the time of this writting (october 2021), still no direct confirmation that dark matter actually exists.
+.METAINFO2
+.
+.SH
+Conclusion
+.PP
+Even if dark matter isn't observed, gravitational lensing still provided the clusters' mass.
+This is confirmed by independant estimates of the clusters' mass.
+For example, the X-rays emissions of a cluster are related to the temperature of its gas, which itself is related to the cluster's mass.
+And the final result is: the total mass in and around galaxies and clusters only is 30 percent of the total amount of mass needed for our universe to be flat.
+Even if the invisible matter is 40 times more massive than visible matter, this is still way less than required for our universe to be flat.
+
+So we are living in an open universe, expanding forever... or maybe not!
+
+.METAINFO1
+Yes, there is a cliffhanger at the end of the chapter.
+Stay tuned, kids!
 .METAINFO2
 
 .SH
 Random facts
 .PP
+.ft H
 .PS
 .ps 7
 reset
@@ -189,6 +228,7 @@ move to TARGET + (0,-0.7)
 .ps 14
 "Gravitational lensing"
 .PE
+.ft R
 .
 According to Zwicky, gravitational lensing can be useful for:
 .BULLET

universe-from-nothing/header.ms

@@ -1,5 +1,5 @@
 .TL
-a Universe from Nothing
+A Universe from Nothing
 .AU
 Lawrence Krauss
 .AU
@@ -39,5 +39,6 @@ Lastly compiled the
 (day/month/year, you know, like in any sane civilization).
 .br
 .UL Status :
-preface and chapter 1: OK. Chapter 2: just starting.
+preface, chapter 1 & 2 are almost done (maybe require some extra info and polishing, but not much).
+Annexes are WIP.
 .AE