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A-L-E-X
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Science and Astronomy Questions

22 Apr 2017 06:13

Watsisname wrote:
Hornblower, The origin of the highest energy cosmic rays, and why we observe as many as we do despite the expectation that the CMB would apply an important breaking effect to them, is a significant unresolved problem in astrophysics. Dark energy is also pretty darn mysterious, but I'm doubtful that there is any important connection between the two.  

When modeled as a cosmological constant, dark energy is a type of gravitational field (more generally, a correction to the metric of space-time) and so it affects all particles equivalently.

Dark energy also can't accelerate particles in a particular direction.  Intuitively one would think dark energy would expand the universe by "pushing out" on things, but that's actually not how it works -- in cosmology it can't work that way because there is no preferred direction to push from and no walls to push against.  The dark energy is uniform and so it does not apply a net force on anything.   Instead, it affects the expansion of space itself because of its energy density, which changes the metric of space-time.

Didn't we observe some off-the-charts cosmic ray particle a few years ago that had the energy of a fast ball (pretty amazing for a subatomic particle.)  It had extragalactic origins.
 
A-L-E-X
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Science and Astronomy Questions

22 Apr 2017 06:21

Watsisname wrote:
A-L-E-X wrote:
Source of the post I was thinking of using both a UV403 filter and an IR720 filter to filter out visible light and see if I can detect the "invisible" parts of the rainbow with the camera.  Not sure if it's possible because cameras have blocking filters on them.  I can do IR photography- but the camera's blocking filter removes about 8 stops of IR light, and on the other end of the spectrum, about 13 stops of UV light.

Yeah, that's a pretty big reduction, but I guess that means the filters are doing their intended job.  There are some guides online for how to modify the camera with taking the filters out, but it's probably not something you want to try unless you are really serious about it and have equipment to spare.  If you're managing to get some results with the filter in place then that's pretty awesome.  I really enjoy looking at B&W infrared photography -- it gives an amazing way to see the world and can produce some really interesting art.  People's faces in particular are very strange in IR, and landscapes and foliage are neat too.

I'd love to see some shots you have made! :)

A-L-E-X wrote:
Source of the post Some of the amazing things I found out is that although most of us humans have three types of cones to detect color (thus three primary colors), some lucky people have a fourth type of cone (four primary colors!) so they can actually see more color than normal people can?  And who said that superhumans didn't exist

I've heard of this and it does sound pretty interesting.  And there are other superhuman senses as well.  I had the privilege to meet a "supertaster" who puts that skill to use as the blendmaster of a tea company.  People also generally have a broader range of hearing when they are young, and lose the sensitivity to high frequencies as they age.  I used to be very sensitive to higher frequencies than normal, and have a vivid memory of walking through a neighbors yard with some friends and was suddenly incapacitated by a soul-piercing sound that nobody else could hear.  Turns out we had walked in front of a motion-sensitive deer deterrent that throws out ultrasound.

This gets more into the realm of neuroscience than color theory, but have you ever heard of a condition called hemineglect?  I think it's one of the weirdest things about how people can perceive the world differently.

The photosynthesis of plants really stands out in IR and I feel like you can see a bit under the skin with it also, which is why it creates those haunting portraits.  I've also done false-color images in IR, you must take care to keep the WB at its lowest possible temperature- I keep it at 2000K- otherwise the picture becomes overwhelmed with red (and with blue when you flip color channels.)
Wow, the supersensing thing is intriguing!  I've heard that as young children we can see many more stars (and even the Galilean moons of Jupiter!) and some children even report being able to see the moon move across the sky.  As we get older our vision deteriorates.  Although some sharp sighted adult viewers have reported being able to see stars all the way down to Mag 8.5 from high altitude/low light pollution locations.
Hemineglect? Never heard of it- but just breaking down the term, does it have to do with some senses atrophying because we don't use them as much when we get older?  Just a shot in the dark lol.
 
A-L-E-X
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Posts: 247
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Science and Astronomy Questions

22 Apr 2017 06:24

Watsisname wrote:
Hornblower, The origin of the highest energy cosmic rays, and why we observe as many as we do despite the expectation that the CMB would apply an important breaking effect to them, is a significant unresolved problem in astrophysics. Dark energy is also pretty darn mysterious, but I'm doubtful that there is any important connection between the two.  

When modeled as a cosmological constant, dark energy is a type of gravitational field (more generally, a correction to the metric of space-time) and so it affects all particles equivalently.

Dark energy also can't accelerate particles in a particular direction.  Intuitively one would think dark energy would expand the universe by "pushing out" on things, but that's actually not how it works -- in cosmology it can't work that way because there is no preferred direction to push from and no walls to push against.  The dark energy is uniform and so it does not apply a net force on anything.   Instead, it affects the expansion of space itself because of its energy density, which changes the metric of space-time.

This is all very interesting- the three "darks" I wonder about are dark energy, dark matter and dark flow.  There is also the "Great Attractor" and why do superstructures in the universe resemble the structure of neural networks of our own brains?  Maybe on a fractal level there is an equivalency (just on different scales) because they are both quantum computers.
 
A-L-E-X
Explorer
Posts: 247
Joined: 06 Mar 2017

Science and Astronomy Questions

22 Apr 2017 07:02

Here is something you might like

http://quantamagazine.us1.list-manage.c ... e76a2a020f

[table][tr][td][size=175][color=#f18121]A Cosmic Burst Repeats, Deepen­ing a Mystery[/color][/size]

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[table][tr][td][img=564x0]https://gallery.mailchimp.com/0d6ddf7dc1a0b7297c8e06618/images/6120a1a3-ca15-4886-a180-70c035ce2dd3.gif[/img]
After a surprise discovery, astrophysicists are racing to understand superenergetic flashes of radio waves that sometimes beep out from distant galaxies.

http://quantamagazine.us1.list-manage1. ... e76a2a020f

[color=#f18121]Related: The Particle That Broke a Cosmic Speed Limit[/color]

Physicists are beginning to unravel the mysteries of ultrahigh-energy cosmic rays.
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