15 Lecture I have made an updated powerpoint set of slides, which simplifies a number of the graphs and adds animation and/or multiple slides to show you how the ideas unfold. You may want to have this open while you're going through these notes. It's L15_updt.ppt from "presentations" directory on my website. 06:59 text error: "which is similar to TO the 1,000 mph...." Remove second "to" 07:28 Please make the text simpler, rather than following my language explicitly: big waves small frequency small waves big frequency please align them nicely so it's an implicit table. 07:37 I'm introducing 3 properties: loudness; pitch; quality. Can we have a low text bar that just identifies each (this is sort of done for the second two but not this first one). So very simply "1. Loudness" 07:44 Please highlight "pressure variations" with a little oval around P; and then the "average pressure" P0 with it's arrow. my language doesn't use the subscript "0" so omit this. exponent's not visible make larger (or could omit since I don't refer to them, in which case remove the parentheses from the "thousandth" etc). 08:24 Again, intro text with possibly simpler following text: 2. Pitch Frequency = waves passing per second. 08:50 I think the full text in the box isn't always the best approach. In this example I think a cleaner approach is: Octave above 880 Hz Concert A 440 Hz Octave below 220 Hz Put the first (middle) line up first, and then the next two as I say them. This then gives the notion of sequence clearer, and "high" on the sequence is "high" pitch. 08:58 Again cleaner text:
Human range: 20 Hz 20 kHz 09:27 Again, simpler text: "3. Quality" 09:47 These diagrams need cleaning up a bit. Look at updated slide 3 for how it should be Label the axes properly (the little dB/kHz down on the lower left is no good). x-axis label: kHz y-axes label: decibels y-axis number should be as I've indicated NOT as shown on the original graph. Make the flute appear LARGER Remove the musical staff and it's note. 10:26 Highlight JUST THE FIRST PEAK, not the first four Then use little arrows to identify all the other peaks (not a group, as currently done). 11:11 Please carry over the changes to the first two graphs to this combined graph. In particular, don't show the musical staffs and their notes (which are utterly confusing for reasons I don't want to get into). 11:43 I still need to provide a noise sound and its spectrum. 12:35 Simpler text: "At 100,000 yrs:" (maybe centered) "2000 protons and" electrons per cm3 "3 thousand billion photons per cm3" Then right brace to lower two and to the right: (or use 4 lines) "6000 K" 13:06 Simpler text: "photon-baryon gas" 13:52 simpler text: Pressure depends on: 1. Temperature 2. How many particles per cubic centimeter.
14:30 simpler text: "First: photons provide almost all the pressure" 15:00 simpler text "Second: primordial pressure is about a millionth of our atmosphere's. 15:15 Simpler text "Third: speed of pressure waves is incredibly fast." Then at 15:31 just add "Third: speed of pressure waves is incredibly fast" "About 60% of light speed" 16:25 You've chosen waves seen obliquely so they appear predominantly horizontal. This is NOT a good image to use. The one in my ppt is better. Please use it or find one equivalent. (update slide 6) Also, please follow my "blow up" square because (as we'll see next lecture) it's only the really small patches that are sound waves so we need to suggest that it's only when you zoom in that you find the sound waves. The box size I chose is about right. 17:19 Don't go to full screen. Simple text box below: "Brightness variation 1/10,000 P/P" Notice I'm using approximately equals; and its P/P NOT / which is what you currently have. 18:00 Again no need for full text box filled with my words! Simple text box in lower third: "angular size of patches physical size (light years) = wavelength" Then next line "Typically: 40,000 700,000 light years. Huge waves!" 19:03 Again, simpler text: After the two line sentence "The Universe's organ pipes are roughly the horizon size (400,000 light years)" Simply add the line " 50 octaves below human range"
21:02 I'm afraid this animation contains some serious errors that need to be changed I wish you had discussed with me how we might do this first! The primary problem is that the outer "photon-baryon gas" is depicted as little spheres almost like stars. But I've been trying to stress that it is a SMOOTH GAS. This seriously undermines the picture I'm trying to construct. Replace the surrounding dots with a slightly patchy diffuse yellow fuzz. Don't rotate the viewpoint I know this gives the 3-D sense, but it introduces the notion of rotation which we DON'T WANT. Now have the yellow slightly textured fuzz move towards the dark matter region, getting more compressed. Don't make it go too far in the current version is way too much we're wanting to evoke the idea of SLIGHT bouncing in and out. About the dark matter region. This is possibly OK, but I dislike the idea of a shiny hard surface remember this also is jus a lightly denser region. Can we make it a bit fuzzy also, and still make it look 3-D? Actually, none of this really needs to be 3-D we can get the idea perfectly well with a planar depiction of the fuzzy dark matter regon (approximately circular) with the diffuse yellow gas falling in and bouncing out. 22:38 This figure needs some work. See my updated ppt slide 7. 1) Make the peaks orange/yellow and the troughs blue and the average background green like in the CMB image (the figure I had was only B&W so missed this opportunity. 2) Don't make these 3-D with shiny surface. I don't want to confuse surface waves in height with flat patchiness of pressure waves. This applies both to the peaks/troughs and the overall CMB surface itself. 3) The oval-skys are a bit small make better use of the image plane as in my ppt. 4) Please label at the top aligned with the two columns: "Sky Maps Sound Spectra" as in my ppt. 5) Introduce the sound spectrum plot with each of the three wave sizes (because otherwise the spectra aren't up there long enough). When I say, for example: "medium waves of medium frequency. Then highlight the peak of the corresponding sound spectrum on the right (and same for the long waves and short waves). 6) When I then say at 22:41 "each size wave contributes" please highlight the right hand spectra. 7) Remove the confusing annotations at the bottom left: C() = loudness; and = 180/patch size(degrees). Let's rely on the next point to communicate that. 8) Please write C() not Cl which just happened to be the convention of the person I took the figure 9) from. Title for this visual: "Sound Spectrum from Patch Size" 22:57
Modify text box, please write: "C(): C is loudness; is frequency." Not C-of-. Notice C is italic 23:17 See updated slide 8 this needs some tweaking. Can we improve on the way this is presented the white box in a black background isn't very good. Please follow my axis labels exactly: Top x-axis is: "Patch Size (degrees)" don't use a little circle. Along the bottom, "Big Patches" and "Small Patches", vertically stacked. Simplify the lower x-axis label "Frequency ()" Include the " data" and pink line labeled "model". Notice I've also enhanced the prominence of the model line because it was a bit faint but not so much as to cover the datapoints! Clean up the left and right y-axis removing all tick marks. 23:38 when I say "with an unmistakable fundamental and harmonics" please insert these labels, in two colors to clearly identify the difference between the fundamental and the harmonics (see animation to slide 8) 24:24 When playing the sound, have the full spectrum up with the "fundamental" and "harmonics" labels still up there. Make sure the volume of the sound is somewhat stronger than the basic volume of my voice (obviously, don't overdo it, but it would be good to be a prominent sound). There is a single click in you sound version which isn't in the sound file I provided can we track this down and remove it, or try re-inserting my file again. Its filename is "slide13_s_cofl_conc_R_5s.wav". 25:44 You go to the figure too soon. Show my description of the first compression with hand movements up to about 25:54. Go to updated slide 9, When I say "show up as the fundamental" label "1st compression" When I say "700,000 light years in size and about 1 degree on the sky" highlight the peak location AND THE UPPER SCALE as in my slide which uses the oval. Then come back to me at 26:03 Return to the figure at 26:14 Label the 3rd peak with the label: "2nd compression" Come back to me around 26:18 26:35 Simpler text:
Odd harmonics are called "compression peaks" 25:51 Now show updated slide 10 with the two rarefaction peaks labeled. 27:02 Simpler text: Even harmonics are called "rarefaction peaks" leave out the "So the..." it's not necessary. 28:20 This figure also needs some adjustments. See my updated slide 11. We have a problem here, because my language refers to "the black line" but with a black background this won't work. Maybe we need a sound fix? I'll assume that's what we'll do. Also If possible I'd like to use green for the P(k) since this will keep recurring and it's good to use color to fix that association. Currently is it orange on your figure (red on mine). Remove all sub-tick marks they just add confusion to the image. The blue line hasn't been copied accurately, the harmonic peaks are too sharp please copy the diagram accurately. Please put the words "Corrupted" and "Pure" in quotes, as in my ppt, these are colloquial terms that only allude to what is actually the case. Change "Actual" to "True" since that's the word I use in the lecture. Let's keep the x-axis label simpler: just "Frequency: or k" since I've not yet really introduced what "k" is. Let's make the y-axis "Loudness" again, for clarity. 28:26 The way of highlighting these sounds as they play by changing their color is quite confusing. A better way is simply to put a "glow" around each line when it's being played. Again the sound file has several bad "clicks" which aren't in my original. We need to sort this out. 29:05 This figure also needs revision. See updated slide 12. Please follow this closely. Labels all need to be clearer Remove the white line on the left plot (which had been C(l) ) Remove the dense y-axis scale on the right plot and replace with equal scale to left plot. Label the left most axis "Decibel Scale" This is important and needs to be highlighted when I say it...