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Pseudo objects


YaDinghus

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As mentioned in linked post I would like to discuss pseudo-objects. I couldn't find a definition online that wasn't about grammar, linguistics or programming. Maybe they are referred to by another name in physics.

They are definitely not quasi-partjcles like phonons or 'holes' in an electrical conductor. 

One example would be a shadow cast by an object. If the source of the shadow and the surface onto which the shadow is cast are sufficiently distant from eachother, it is possible for the shadow to break the speed of light (even though the information that the shadowcaster has moved only reaches the shadow with the speed of light). It's a rather well known phenomenon.

I have attempted to define pseudo-objects in the 2D object thread, but I have a feeling that it's not a complete definition, only one that was sufficiently useful at the time. If you know a definition - also possibly a more official technical term - off the top of your head, or if you would like to help me find a definition for this class of objects any other way, I would be much obliged

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4 minutes ago, YaDinghus said:

As mentioned in linked post I would like to discuss pseudo-objects. I couldn't find a definition online that wasn't about grammar, linguistics or programming. Maybe they are referred to by another name in physics.

They are definitely not quasi-partjcles like phonons or 'holes' in an electrical conductor. 

One example would be a shadow cast by an object. If the source of the shadow and the surface onto which the shadow is cast are sufficiently distant from eachother, it is possible for the shadow to break the speed of light (even though the information that the shadowcaster has moved only reaches the shadow with the speed of light). It's a rather well known phenomenon.

I have attempted to define pseudo-objects in the 2D object thread, but I have a feeling that it's not a complete definition, only one that was sufficiently useful at the time. If you know a definition - also possibly a more official technical term - off the top of your head, or if you would like to help me find a definition for this class of objects any other way, I would be much obliged

Thing is, a shadow is almost exactly like an electron hole, in that you are describing the behavior of the absence of something, because it's the easier thing to describe.

 

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2 minutes ago, swansont said:

Thing is, a shadow is almost exactly like an electron hole, in that you are describing the behavior of the absence of something, because it's the easier thing to describe.

 

True, that's why I explicitly said it wasn't that. The 'opposite' phenomenon resulting in the same apparent paradox is a (very strong) laser pointer being aimed at the moon and the point moving faster than the speed of light from just wiggling the pointer a few arcsecs. The holes in a conductor only move in the opposite direction as the electrons filling it, but with the same speed as the electrons

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I'm not at all convinced by any comparison between 'shadows' and 'holes'.

I think holes in the electronic sense are more akin to holes in the ground.

Both types of hole can be there whether they are filled or not.

A shadow requires the light and a blocking object.

 

I really don't know what you mean by a 'pseudo object' but I would have thought definition must depend upon what you want it to do?

Edited by studiot
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1 hour ago, studiot said:

I'm not at all convinced by any comparison between 'shadows' and 'holes'.

I think holes in the electronic sense are more akin to holes in the ground.

Both types of hole can be there whether they are filled or not.

A hole that's filled with dirt is still a hole?  Your backyard is comprised of millions of holes, but the dirt is still in them and grass is on top? Doesn't that make the concept of a hole kind of meaningless?

1 hour ago, studiot said:

A shadow requires the light and a blocking object.

Right. You are defining a region based on what's not there, instead of what is there, much like you define a hole. 

 

5 hours ago, YaDinghus said:

True, that's why I explicitly said it wasn't that.  

But you said it was that: "One example would be a shadow cast by an object."

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8 minutes ago, swansont said:

A hole that's filled with dirt is still a hole?  Your backyard is comprised of millions of holes, but the dirt is still in them and grass is on top? Doesn't that make the concept of a hole kind of meaningless?

Right. You are defining a region based on what's not there, instead of what is there, much like you define a hole. 

 

Well perhaps the leprachauns have been infilling holes in my yard, but I was thinking more of that famous observation by A. Puddle. "You know this hole exactly fits my shape requirements!"

That would certainly be more in line with my yard.

:)

 

The point I was making (indirectly) is that the oft quoted holes move in the opposite direcftion to electrons is bullshit.

Holes are vacant levels in a (quantum) energy level spectrum and there whether they are filled or not ( eg by suitable dopants).

But they do not actually move, although it is convenient to assign them an effective mass and a mobility coefficient.

 

Pseudo objects?

I still don't know.

What is an object to be pseudo?

We already have pseudo vectors in Physics, which are vectors that  swing the other way.

 

:)

Edited by studiot
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14 hours ago, swansont said:

But you said it was that: "One example would be a shadow cast by an object."

And then I offered another example:

19 hours ago, YaDinghus said:

The 'opposite' phenomenon resulting in the same apparent paradox is a (very strong) laser pointer being aimed at the moon and the point moving faster than the speed of light from just wiggling the pointer a few arcsecs

So far pseudo objects as I referred to them seem to cover projections only. Maybe that's all they are. I was wondering if there were other phenomena that at first glance violated the laws of physics - which holes clearly do not - and appeared to be objects. If nobody can think of any, that's ok and I'll take projections

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17 hours ago, studiot said:

I'm not at all convinced by any comparison between 'shadows' and 'holes'.

I think holes in the electronic sense are more akin to holes in the ground.

Both types of hole can be there whether they are filled or not.

A shadow requires the light and a blocking object.

 

I really don't know what you mean by a 'pseudo object' but I would have thought definition must depend upon what you want it to do?

My avatar (top left of this post) is a screen capture of a feedback loop that comprised a digital camera pointed at a computer screen. (if you right click on the avatar and select open image in new tab you will see the edges of the window) The camera was on a pedestal approximately 3 feet from the screen and was set so that the light from the square viewing window was being fed back and was twisted into the spherical shape you see due to lag at the extremities i.e. the previous screen captures, at 25 frames per second via the camera's CCD, are twisted due to the camera being at 3 different angles to true 90 degrees in front of the screen and form the consistent spherical shape. I placed my finger onto the screen and removed it within 1.7 seconds to introduce a shadow into the feedback loop. 

The shadow in the centre of the spherical shape is a 'pseudo object' that consists of a truncated conical shadow that exists in the feedback loop between the screen and the cameras CCD at all times. The image shown is half way to the final state that appears like a stable halo with a ring of waves travelling in opposite directions around the outside and inside of the halo. The initial spherical shape in the feedback loop is stable and the halo formed by inserting a shadow into the feedback loop also remains stable while undisturbed. Once the halo shape is disturbed it reverts back to the stable spherical shape.

If anybody would like a series of images of the feedback loop setup and various images pm me with your email address. All the images are screen captures and they are exactly what you see with your eyes when you view the feedback loop in a dark room.

Edited by LaurieAG
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I noticed that I can post images so here are a series of images as referred to above.

I made them around 20 years ago and I suspect they are hardware dependent i.e. the Pentium 233 MMX was the first CPU with built in graphics processing and the CRT is necessary for the behaviour of the display. So you probably won't be able to duplicate them with a modern PC/LED display and camera.

Technically the screen capture images are Poincare sections of photons/light travelling around in a circle. The photons travel through air between the screen to the camera's CCD, via encrypted electronic charges from the CCD to the CRT and finally as electrons in a vacuum through the CRT to the phosphors on the screen. If you look into things in more detail you will see that the final stable halo state is actually an "Einstein Ring" so the ones we see in our astronomical observations must be in sync with the rotation of the object going around/in front of a star and our observational granularity/depth of field.

At no stage do you actually see the photons travelling between the screen and the CCD with your eyes but they must exist or the images would not be produced so they are 'pseudo objects' to our eyes. Unfortunately I never managed to get an image of the final stable halo state, it is so fascinating and mesmerising that I clean forgot to take a screen shot. I only managed to get to this state twice because you must place your finger on the screen in the dead centre of the orb shape and get it out within 1.7 seconds or you won't get it right. When you do get it right the orb swells outwards and goes into the stable halo state with the counter rotating waves running around the inside and outside. 

The other images shown show various other configurations of just the bare loop or with one or 2 mirrors introduced into the loop, in number 4 I placed my finger on the screen next to the orb shape.

0-Setup.jpg

1-Winiverse.jpg

2-FernShell.jpg

3-PerfectOrb.jpg

7-Blackhole.jpg

9-Nanotube1Mirror.jpg

15-Misc2Mirror.JPG

10-aFractal2Mirrors.JPG

4-Startled.jpg

8-Fractal1Mirror.JPG

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It's also interesting what other objects, pseudo or otherwise, you can capture with a feedback loop with the camera at various different angles, with or without mirrors.

If you right click on an image and select view image in new tab, you will see the number of mirrors in the image name.

12-RiemannSphere1Mirror.JPG

00aPoincareSection.jpg

11-flare2Mirrors2.JPG

6-OrangeCloud.jpg

5-BlueHand.jpg

13-LightTree2Mirror.JPG

14-DarkTree2Mirrors.JPG

16-Misc2Mirror.JPG

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8 minutes ago, LaurieAG said:

It's also interesting what other objects, pseudo or otherwise, you can capture with a feedback loop with the camera at various different angles, with or without mirrors.

If you right click on an image and select view image in new tab, you will see the number of mirrors in the image name.

I suppose there are many ways you can call up a 'pseudo' something.

The false radar images of invasion fleets in Operation Taxable and Operation Window were one such.

False sonar images off thermal layers are another.

Here is one you can try yourself.

Hold your two hands about 400mm in fornt of your face with the tips of your index fingers pointing at each other about 50mm apart.
Watch carefully while you bring the fingers closer to your face.

At some point a pseudo 'double ended' finger appears to hover in space between them.

Or we could get more mathematical and talk about 'pseudovectors'.

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1 hour ago, studiot said:

I suppose there are many ways you can call up a 'pseudo' something.

... Or we could get more mathematical and talk about 'pseudovectors'.

There are not many 'pseudo' objects that can be collected or modelled electronically apart from things like Einstein rings and crosses. 

https://nyti.ms/2nH0L4f

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43 minutes ago, LaurieAG said:

There are not many 'pseudo' objects that can be collected or modelled electronically apart from things like Einstein rings and crosses. 

https://nyti.ms/2nH0L4f

I would have thought both the first two of my examples were purely electronic and the third could be modelled electronically with suitable digital optical equipment.

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