How an atomic clock works, and its use in the global positioning system (GPS) by EngineerGuy (2012)
Source. Shows how conceptually an atomic clock is based on a feedback loop of two hyperfine structure states of caesium atoms (non-radioactive caesium-133 as clarified by the Wikipedia page). Like a quartz clock, it also relies on the piezoelectricity of quartz, but unlike the quartz clock, the quartz is not shaped like a tuning fork, and has a much larger resonating frequency of about 7 MHz. The feedback is completed by producing photons that resonate at the right frequency to excite the caesium.Inside the HP 5061A Cesium Clock by CuriousMarc (2020)
Source. A similar model was used in the Hafele-Keating experiment to test special relativity on two planes flying in opposite directions. Miniaturization was key.
Contains a disposable tube with 6g of Caesium. You boil it, so when it runs out, you change the tube, 40k USD. Their tube is made by Agilent Technologies, so a replacement since that opened in 1999, and the original machine is from the 60s.
Detection is done with an electron multiplier.
youtu.be/eOti3kKWX-c?t=1166 They compare it with their 100 dollar GPS disciplined oscillator, since GPS satellites have atomic clocks in them.
Quick presentation of the atomic clock at the National Physical Laboratory (2010)
Source. Their super accurate setup first does laser cooling on the caesium atoms.This chick is hardcore.
Beautifully argued at: Can't get you out of my head by Adam Curtis (2021).
- The Quantum Story by Jim Baggott (2011) page 10 mentions:and the footnote comments:
Early examples of such cavities included rather expensive closed cylinders made from porcelain and platinum.
- 1859-60 Gustav Kirchhoff demonstrated that the ratio of emitted to absorbed energy depends only on the frequency of the radiation and the temperature inside the cavity
- 1896 Wien approximation seems to explain existing curves well
- 1900 expriments by Otto Lummer and Ernst Pringsheim show Wien approximation is bad for lower frequencies
- 1900-10-07 Heinrich Rubens visits Planck in Planck's villa in the Berlin suburb of Grünewald and informs him about new experimental he and Ferdinand Kurlbaum obtained, still showing that Wien approximation is bad
- 1900 Planck's law matches Lummer and Pringsheim's experiments well. Planck forced to make the "desperate" postulate that energy is exchanged in quantized lumps. Not clear that light itself is quantized however, he thinks it might be something to do with allowed vibration modes of the atoms of the cavity rather.
- 1900 Rayleigh-Jeans law derived from classical first principles matches Planck's law for low frequencies, but diverges at higher frequencies.
Black-body Radiation Experiment by sciencesolution (2008)
Source. A modern version of the experiment with a PASCO scientific EX-9920 setup.This situation is the most bizarre thing ever. The dude was fired in 2020, but he refused to be fired, and because he has the company seal, they can't fire him. He is still going to the office as of 2022. It makes one wonder what are the true political causes for this situation. A big warning sign to all companies tring to setup joint ventures in China!
Near Los Angeles.
The other major university in the Bay Area (and basically in California itself) besides a few University of California places.
The heart of Silicon Valley.
- battery life:
- 2023-04: on-browser streaming + light browsing on Ubuntu 22.10: about 2h45. Too low! Gotta try buying a new battery.
- 2022-01-04 updated firmward after noticing that ubuntu 21.10 does not wake up from suspend seemed to happen every time when not connected to external power.
dmidecodediff excerpt:used the "Ubuntu Software" GUI as mentioned at: support.lenovo.com/gb/en/solutions/ht510810-how-to-do-software-updates-linux. Kudos for making this accessible to newbs.BIOS Information Vendor: LENOVO - Version: N1UET40W (1.14 ) - Release Date: 09/28/2017 + Version: N1UET71W (1.45 ) + Release Date: 07/18/2018After doing that, another update became available to: 0.1.56, clicked it and was much faster than the previous one, and didn't auto reboot. After manual reboot,dmidecodediffed again:plus a bunch of other lines.BIOS Information Vendor: LENOVO - Version: N1UET71W (1.45 ) - Release Date: 07/18/2018 + Version: N1UET82W (1.56 ) + Release Date: 08/12/2021 - 2021-06-05 upgraded to Ubuntu 21.04 with a clean install from an ISO. SelectedAfter this, the GUI felt fast, who would have thought that erasing a bunch of stuff would make the system faster!
- "Minimal installation"
- "Erase disk and install Ubuntu". Notably, this erased the Microsoft Windows that came with the computer and was never used not even once
- "Erase disk ans use ZFS"
- Encrypt the new Ubuntu installation for security
lsblkcontains:andzd0 230:0 0 500M 0 disk └─keystore-rpool 253:0 0 484M 0 crypt /run/keystore/rpool nvme0n1 259:0 0 476.9G 0 disk ├─nvme0n1p1 259:1 0 512M 0 part /boot/efi ├─nvme0n1p2 259:2 0 2G 0 part │ └─cryptoswap 253:1 0 2G 0 crypt ├─nvme0n1p3 259:3 0 2G 0 part └─nvme0n1p4 259:4 0 472.4G 0 partlsblk -f:zd0 crypto_LUKS 2 └─keystore-rpool ext4 1.0 keystore-rpool nvme0n1 ├─nvme0n1p1 vfat FAT32 ├─nvme0n1p2 crypto_LUKS 2 │ └─cryptoswap ├─nvme0n1p3 zfs_member 5000 bpool └─nvme0n1p4 zfs_member 5000 rpooThen:contains:grep '[rb]pool' /proc/mountswhich gives an idea of how the above map to mountpoints.rpool/ROOT/ubuntu_uvs1fq / zfs rw,relatime,xattr,posixacl 0 0 rpool/USERDATA/ciro_czngbg /home/ciro zfs rw,relatime,xattr,posixacl 0 0 rpool/USERDATA/root_czngbg /root zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/srv /srv zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/usr/local /usr/local zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/games /var/games zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/log /var/log zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/lib /var/lib zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/mail /var/mail zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/snap /var/snap zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/www /var/www zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/spool /var/spool zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/lib/AccountsService /var/lib/AccountsService zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/lib/NetworkManager /var/lib/NetworkManager zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/lib/apt /var/lib/apt zfs rw,relatime,xattr,posixacl 0 0 rpool/ROOT/ubuntu_uvs1fq/var/lib/dpkg /var/lib/dpkg zfs rw,relatime,xattr,posixacl 0 0 bpool/BOOT/ubuntu_uvs1fq /boot zfs rw,nodev,relatime,xattr,posixacl 0 0
2020-06-06: dropped some lemon juice on the bottom left of touchpad. Bottom left button not working anymore... I'm an idiot. There are many other alternatives, but very aggravating, I'll replace it for sure. Can't find the exact replacement part or any videos showing its replacement online easliy, dang. For the T430: www.youtube.com/watch?v=F3lzV9uXRjU Asked at: forums.lenovo.com/t5/ThinkPad-P-and-W-Series-Mobile-Workstations/P51-left-bottom-button-below-trackpad-mouse-left-click-stopped-working-possible-to-replace/m-p/5019903 Also I could not access it because you need to remove the HDD first: www.youtube.com/watch?v=5Klawxc7T_Y and I can't pull it out even with considerable force, unlike in the video... And OMG, those button caps are impossible to re-install once removed!!! Then when I put the whole thing back together, the upper buttons were not working anymore. FUUUUUUUUCK. When first opening I pulled on it without properly removing the cap and it came off, but it didn't look broken in any way and I put it back in. Keyboard works thank God, so right black connector is fine, left white one oppears to be the one for upper keys and trackpoint, both of which stopped working. The hardware manual confirms that they are both part of the same device, so basically a mouse :-) TODO can it be bought separately from te keyboard? Doesn't look like it, photo of keyboard part includes those buttons. The manual also confirms that the bottom buttons are one device with the trackpad "trackpad with buttons", thus forming the second entire mouse.
2019-04-17: popup asking about "ThinkPad P51 Management Engine Update" from from 182.29.3287 to 184.60.3561, said yes.
- partition setup: askubuntu.com/questions/343268/how-to-use-manual-partitioning-during-installation/976430#976430
- BIOS:
- for NVIDIA driver:
- for KVM, required by Android Emulator: enable virtualization extensions
- TODO fix the brightness keys:
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