When I was a kid in the mid 80's we had a ball lightning incident.
Some family was over visiting and the adults were sitting in the adjoining dining room with us kids in the living room by the TV.
Lightning struck somewhere close by and a tennis sized ball of electricity entered the dining room through the outside wall. It crossed the room in about a second, went through the wall to enter the living room and then accelerated towards the TV.
When it hit the TV box the TV went out and the house lights flickered for a bit, but everything seemed fine. We turned the TV back on and it had a big purple corner which the degauss function couldn't fix.
Overall it probably lasted about a week before the effect faded enough that it was no longer visible.
From what I can tell, ball lighting doesn't exist. We have lots and lots of people who think they've seen it. But there doesn't seem to be any legitimate footage, which is pretty damning considering there are cameras everywhere now.
You’d think skeptics would learn their lesson after rouge waves. Tons of eyewitness accounts going back to antiquity but no footage, considered a myth for ages.
We even had a bunch of math saying they weren’t possible/probable! (Ex once in an 100M years or so) so they were quite sure of themselves.
The we started to get large scale buoy data and sure enough, rouge waves! (the math was wrong).
Our understanding of earth phenomenon is far from complete. For lightning, red spites/green ghosts/etc are all relatively new discoveries.
Could the same be said about ball lightnings? Many common things became suspiciously rare after invention of pocket cameras.
I’m not questioning gp’s credibility, because I also found myself in impossible situations like kitchen pot overheating and exploding dramatically, which supposedly should only happen in controlled lab circumstances. But I understand when people can’t believe.
Added: we also should look for easier explanations, especially when it comes to early memories. Kid’s imagination is a powerful thing.
Rogue waves are actually a good example. They occur in places where there’s usually no recording equipment, and almost no one claims to have seen one. Yet numerous ones have been identified.
Ball lightning supposedly occurs in places where there’s recording equipment everywhere, and people all over the place claim to have seen it. Yet we don’t have any evidence for it yet.
Yeah, there’s one paper from a decade ago saying they think a spectrograph was showing it. That’s the same paper another response posted, and the same one that kept popping up when I searched for evidence of it. It's the same single piece of evidence that someone brought up when ball lighning was discussed previously on HN[1].
It's telling that the Wikipedia article only lists once occurrence where scientists think they might have seen it, and devotes several paragraphs to it.
I’m not going to say it’s definitively wrong, but when people are reporting it all over the place, and there’s only one scientific paper from years ago that says they might have seen it on the other side of the world a decade ago, it’s hard for me to take it as solid evidence that it exists.
You could close your eyes and then as far as you could tell nothing would exist. Then you could go around calling everyone a liar who claims that reality is still there even though you aren’t seeing it.
All quality CRT TVs are automatically de-gaussed on switch-on. That's the 'toooong' you hear when they turn on.
A magnet might temporarily mess up the magnetic convergence with magnetised spot areas, but that should be fixed on next switch-on.
The Earth’s magnetic field can also affect the picture
That's because when the convergence controls are set correctly, they also take care of the magnetic field of the earth too at the same time. If you turn the TV upside down, you would also have to reset the convergence controls. No biggie, but it is something that needs doing.
> A magnet might temporarily mess up the magnetic convergence with magnetised spot areas, but that should be fixed on next switch-on.
A large enough magnet (or other trauma) can permanently warp the mask or grille --- this is basically unrepairable. The degauss system should undo magnetism eventually, but sometimes it takes several activations.
There's a throwaway comment in here about the earth's magnetic field affecting CRTs and turning the TV upside down, is that actually true? I would have thought the earth's magnetic field would be incredibly weak in comparison to the deflecting coils.
I've had TVs move room to room and face a different direction and need to be fixed with a degaussing coil. I'm told it's from the Earth's magnetic field. Could also be that they were next to other TVs (arcade machines in this case).
If i had to guess, i bet it's the other machines nearby. I'm sure we've all felt the static from a crt screen when it's turned off. Being in a closed room of turned on crt's would probably create a significant field of potentials around the room. I can't imagine the earth's magnetic field is so erratic as to change noticeably from room to room. I'd think any variation of that order would disrupt the functioning of compasses, and the phenomena couldn't just be localized to your one room on earth, compasses would be somewhat unreliable all over the globe then.
But who knows, maybe a solar flair hit you between rooms and changed the environment enough to disrupt the tv, but then i'd bet it'd effect all the machines. Eh, who knows. Weird thing that electromagnetism
I've got a cocktail video game, and the top (which the screen is mounted to) is on a hinge. There's a decent degauss on start, so if you start it with the screen up, it's fine, and if you start it with the screen down, it's fine, but if you move it while it's on, the colors get weird.
Rotation can affect image purity. You don't even have to turn the set upside down. If you have a set that already has some color purity issues due to bad magnetism of the mask, you can affect that (and sometimes even find a position that eliminates it) simply by rotating the TV around on the surface it rests on.
I just sent an email to my old high school buddy. I'm sure this is incorrect, and I've asked him for his remembrance of something we did on a lark.
One night David Letterman did an episode where throughout the show, the camera(s) did a full 360 degree revolution.
When the show was half-way through, it was of course, upside down. So we turned the television upside down.
I personally don't remember anything unusual about the way the show appeared, other than that the TV was upside down, and then on its side for a few minutes at the 45 minute mark.
If he responds within a reasonable time, I'll follow up to mention if he remembers this the same way I do.
Actually, this is a perfectly good point - arcade games had their CRTs on a 45 degree angle, some on portrait and some on landscape direction, and they showed no "intermediate" effects that you'd expect if this gravity claim was true. There were even "table" video games where the CRT was 90 degrees upward, which should have really messed things up if this gravitational effect was at all true.
Likewise, remember the green swooping radar of days gone by? In wartime, those regularly got a wild ride through gravity, and yet you never hear of them having a problem with it.
I'm really thinking this article's "throw-away" comment is really worth throwing away.
> Likewise, remember the green swooping radar of days gone by
Monochrome CRTs don't have a shadow mask or an aperture grille, and no degausing or need for it. Certainly, magnetic fields will interact with the electron beam of a monochrome CRT, but if it's the earth's magnetic field, it will be uniform over the whole screen, and not a big deal.
From personal experience, I took a 20" Sony Trinitron from Los Angeles to New Zealand in the mid 90's. the reversal in the Earth's magnetic field between the northern and southern hemisphere's meant I could never completely get the RGB guns to line up correctly.
To me, this sounds a lot like the directional flow of toilets flushing. I'd have to see this as an actual experiment before I can be convinced of what the webopedia page is claiming.
Check out my previous comment on the time a friend and I watch his TV upside down. There was zero difference that I remember.
Consider where most of the monitors are shipped from. Did they send "southern hemisphere" specific televisions and crt monitors? And what happens at the equator?
Could your monitor have been fritzed on the flight? Did it work normally when you brought it back?
This would actually be a fantastic YouTube video, whether it debunks or proves the claim being equally interesting.
This is simply not true. If it were, then a monitor at the equator would be ruined merely by rotating it to face east instead of west, or north instead of south. They would have needed to sell four different monitors, to accommodate customers who were going to face their monitors in different directions. Even away from the equator most of the magnetic field points north/south rather than into or away from the Earth. More likely vibration during shipping defocused your monitor somewhat; a TV–repair shop probably could have fixed it.
It's much more likely that your TV suffered in-transit knocks and bumps that rendered it out of alignment, and too out of alignment to be able to be re-aligned.
Some professional Sony BWM series monitors have menu settings for the direction where the monitor is facing to compensate for the earth magnetic field.
Maybe worth noting in the context of HN: There are two types of electron emissions in a CRT. The primary emission, which produces the visible image, and the secondary emission, which causes an electron well around the excited spot, as free electrons take up positions of the electrons emitted by the primary emission. It's the latter that was utilized in the CRT memory Williams-Kilburn tubes (the first viable random access memory), which detected that local depletion of electrons in the phosphor in the read cycle.
Moreover, there were also dark-trace CRTs or Skiatrons (developed just before WWII and used for Radar during the war), producing a dark-on-light image, which were also based on the secondary emission, rather than the primary one. (Technically, this was based on the displacement of free electrons in an alkali-halide crystal lattice, which made the CRT locally opaque.)
I actually did this, inadvertently, as a kid in the 1980s on my parents' four-channel television set. From what I can remember (I was quite young) it pulled the colour towards the spot where I placed the magnet and left the rest of the image in monochrome. I vaguely remember finding it interesting the way the colours moved around but my parents were less impressed for some reason.
They had it fixed though: a guy came out from the shop with a hand-held degaussing tool and it was just fine afterwards.
One time when I was very young, I was already such a tech-nerd that I chose to attack my father with a magnet, intended to damage his wristwatch.
I was calmly informed that he'd already selected a watch that was immune to magnetic fields. But of course that was a real danger to old-fashioned movements which had many ferrous parts that relied on not sticking together.
I never lived it down. Some of our childish rebellions are ridiculous in retrospect!
> There are many CRTs in your TV or monitor. They are each aimed to deliver electrons to a precise spot on the back of your TV where they excite the phospor in the tiny spot on your TV that the electron hits. Magnets are used to guide the electrons to that precise (and tiny) spot. The excited phosphor molecules at that spot then emit light. All the CRTs working together generate the picture on your TV.
That's incorrect: there aren't many CRTs in a TV or monitor. There's just one in monochrome displays or three in color displays. That paragraph even seems to imply that there is one CRT per dot. I don't think you would even need magnets to guide electrons (much less one set of magnets for all the CRTs): just aim each CRT at the correct location. Seems a weird misconception from someone who calls themselves a physicist.
> There's just one in monochrome displays or three in color displays.
the CRT is the giant glass picture tube, cathode ray tube, there is only one of those in a TV.
For color TV there are 3 "guns" shooting electrons at the different colored phosphors. There is a single system to guide all three electron beams to their respective right parts of the display.
This only applies to color CRTs that use a shadow mask or aperture grille. Monochrome CRTs, and the few color CRTs that don't rely on a piece of metal to ensure the electrons hit only the correct phosphors, are completely immune to lasting damage from a magnet (although in theory a strong enough magnet could alter the magnetism of the existing magnets that correct the set's deflection). A magnet will still distort the image of a monochrome set, but once you remove the magnet, the image should return back to normal.
Back in the days when LCD computer monitors were ridiculously expensive for a 15" monitor, I was at a customer in NYC where they had hundreds rather than the standard 'tv' style monitor of the time. Turns out, they had moved to a new location too near the subway system - and every time the train went by, it would mess with the old displays. Apparently whatever savings they got from the change in location was gobbled up by needing that cutting edge hardware.
Is it just me, or does the article not actually answer the question in the title? It explains the components well, and how a magnet distorts the image, but does not describe which component is capable of being permanently altered by an external magnetic field.
Is it the phosphor coating? The deflecting coils? Some sort of static field in the glass?
A magnet will bend the electron beams, but that isn’t permanent. A permanent color change made by a magnet only happens by imposing a magnetic field on a metallic component of the monitor, so that the beam is always deflected by it. One component not shown in that diagram is the shadow mask, which divides the screen into discrete dots to be activated by the electron beams. This is a very thin piece of metal (or a grid of thin wires in certain cases) that is easily magnetized.
There was a time with some of these larger TVs and monitors where a coil was built into the frame and would energize briefly on power up, or with the push of a button on the control panel.
Oh yes, I well remember the "degauss" button on CRT monitors. We had one where it was basically a mini EMP and would make the images on nearby monitors quiver as well. Fun times.
I know a magnetic field was being retained somewhere, just wasn't sure which component it was.
> This is a very thin piece of metal (or a grid of thin wires in certain cases) that is easily magnetized.
Worse, a strong magnet (especially a modern rare-earth magnet) can bend the shadow mask, causing color distortion which can't be corrected by degaussing.
Oh my goodness, I wonder if that’s what I did to my parent’s TV as a kid? I remember clearly playing with a large hard drive magnet near the TV and causing the TV to change colours - we ended up with a purple blob in one corner that never went away even after many rounds of degaussing and power cycling.
I permanently damaged my family’s tv with a car loud speaker I was playing with as kid. It left a big blemish, colored shadow shape and since we were kinda poor (didn’t know at the time), we lived with it for ages… oh the guilt!
Was fun to understand the election beam was being deflected a magnetic field at the time tho
I ruined a Sony TV in the late 1970's with a pacemaker magnet my father (a physician) brought home from work. My parents were not happy with me. It was able to be repaired.
Some family was over visiting and the adults were sitting in the adjoining dining room with us kids in the living room by the TV.
Lightning struck somewhere close by and a tennis sized ball of electricity entered the dining room through the outside wall. It crossed the room in about a second, went through the wall to enter the living room and then accelerated towards the TV.
When it hit the TV box the TV went out and the house lights flickered for a bit, but everything seemed fine. We turned the TV back on and it had a big purple corner which the degauss function couldn't fix.
Overall it probably lasted about a week before the effect faded enough that it was no longer visible.