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Physics

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Friendly Physics Related Discussion Talking Point: Black Hole Information Paradox tinyurl.com/4ta63p2z Book Club 12th Sept 15:00 BST | Bishop & Goldberg (manifolds) | Try Problems 1.2.1, 1.2.6, 1.2.8 | Book Club Site: tinyurl.com/2sn9upx2 +stardust:matrix.org17 Servers

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15 Sep 2021
@fractal:matrix.orgfractal oh hey blippity bloopy 15:34:10
16 Sep 2021
@jonas:matrix.tjemsland.xyzJonas left the room.13:49:15
@davpp:matrix.orgDavid
In reply to @cynicusrex:matrix.org
Nvm, got my answer here: https://www.physicsforums.com/threads/calculating-the-weight-of-1-atomic-mass-unit.905925/
Good stuff :) It's a very important discrepancy!
16:52:55
@davpp:matrix.orgDavidAnybody going to any conferences this season? 16:53:17
18 Sep 2021
@twodots:matrix.org@twodots:matrix.orgYo gang. Please forgive me if this is too basic for the audience here, but as a filthy casual, I've been enjoying this channel lately: https://www.youtube.com/c/CoolWorldsLab/videos The guy apparently is an astrophysicist himself, and he just speculates about stuff, but within the boundaries of the physics we know. It's like good sci-fi in the video format.09:25:06
@twodots:matrix.org@twodots:matrix.org * Yo gang. Please forgive me if this is too basic for the audience here, but as a filthy casual, I've been enjoying this channel lately: https://www.youtube.com/c/CoolWorldsLab/videos The guy apparently is an astrophysicist himself, and he just speculates about stuff, but within the boundaries of the physics we know. It's like good sci-fi in the video format.09:26:17
@chile09:matrix.orgchile09
In reply to @ga48juv:matrix.org
sry poor choice of wording. they propose a mesh as a mirror. everything that fits through the mesh can only hit a small part of (1 knot or wire). also what is the probability of the area that the net spans getting hit?
what type of net are you talking about here?
13:42:12
@karuta_p:matrix.orgkaruta_p joined the room.14:21:36
@chile09:matrix.orgchile09how do you make a mirror out of a mesh17:51:11
@chile09:matrix.orgchile09what materials is it made out of17:51:18
19 Sep 2021
@tpt72e4g:nitro.chat@tpt72e4g:nitro.chat left the room.09:40:32
@davpp:matrix.orgDavid

It's a radio telescope, so it isn't a mirror for optical light which you are familiar with e.g. https://www.skatelescope.org/wp-content/uploads/2016/04/CSIROs-Parkes-radio-telescope-day.jpg How "fine" your mesh needs to be depends on the wavelength. The mirror in your house is probably just a "mesh" of silver atoms with some glass to protect it. Much like with traditional optical mirrors though, they are made out of conductors. Electromagnetic fields that reach the telescope cause the electrons in the metal to move which causes a "reflection".

I'm not in the field so I'm not 100% sure what materials they'll use, but I would imagine scientists want the best conductor they can get but the exact conductor they use will probably come down to practicalities for the structure like strength, the large expected changes in temperature, the weight to launch, corrosion, cost etc. I know the Lovell telescope in the UK is steel. Aluminium is relatively cheap, light, and a good conductor, but isn't as strong.

13:33:50
@fractal:matrix.orgfractal
In reply to @davpp:matrix.org

It's a radio telescope, so it isn't a mirror for optical light which you are familiar with e.g. https://www.skatelescope.org/wp-content/uploads/2016/04/CSIROs-Parkes-radio-telescope-day.jpg How "fine" your mesh needs to be depends on the wavelength. The mirror in your house is probably just a "mesh" of silver atoms with some glass to protect it. Much like with traditional optical mirrors though, they are made out of conductors. Electromagnetic fields that reach the telescope cause the electrons in the metal to move which causes a "reflection".

I'm not in the field so I'm not 100% sure what materials they'll use, but I would imagine scientists want the best conductor they can get but the exact conductor they use will probably come down to practicalities for the structure like strength, the large expected changes in temperature, the weight to launch, corrosion, cost etc. I know the Lovell telescope in the UK is steel.

😯 it's beautiful... ❤️
15:45:37
@davpp:matrix.orgDavid
In reply to @chile09:matrix.org
how do you make a mirror out of a mesh
*

It's a radio telescope, so it isn't a mirror for optical light which you are familiar with e.g. https://www.skatelescope.org/wp-content/uploads/2016/04/CSIROs-Parkes-radio-telescope-day.jpg How "fine" your mesh needs to be depends on the wavelength. The mirror in your house is probably just a "mesh" of silver atoms with some glass to protect it. Much like with traditional optical mirrors though, they are made out of conductors. Electromagnetic fields that reach the telescope cause the electrons in the metal to move which causes a "reflection".

I'm not in the field so I'm not 100% sure what materials they'll use, but I would imagine scientists want the best conductor they can get but the exact conductor they use will probably come down to practicalities for the structure like strength, the large expected changes in temperature, the weight to launch, corrosion, cost etc. I know the Lovell telescope in the UK is steel. Aluminium is relatively cheap, light, and a good conductor, but isn't as strong.

16:15:39
@chile09:matrix.orgchile09Has graphene mesh ever been tested in the realm of opto-electronics or radio electronics17:57:39
@chile09:matrix.orgchile09I remember reading about material band gaps and how that property is particularly important18:00:53
21 Sep 2021
@chile09:matrix.orgchile09graphene doesn't have much of a band gap mind you; it would maybe be hyper-reactive00:02:31
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22 Sep 2021
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23 Sep 2021
@twodots:matrix.org@twodots:matrix.org left the room.11:42:20
@cynicusrex:matrix.orgΨ ^ Cynicus RexAnyone experienced with Symbolab?19:20:29
@cynicusrex:matrix.orgΨ ^ Cynicus RexPretty amazed, and find it to be more user friendly than Wolfram Alpha19:20:57
@davpp:matrix.orgDavidThese days I use maxima more than wolfram alpha. WA definitely has more solutions available, but generally maxima can do what I want.21:04:01
@davpp:matrix.orgDavidI also use Abramowitz & Stegun 21:04:57
@davpp:matrix.orgDavidSometimes the computer tools can give an answer but mangle the form, whilst the old tables generally have legible forms. Both are good. 21:11:27
24 Sep 2021
@chile09:matrix.orgchile09what type of math are you doing with these apps?00:28:39

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