Glass Does Not Flow. Except in Space?
This is a guest post by Kenneth Zhang, a time science reporter. ]
In this week\'s Science Times section, I wrote that glass is more than just a slow
Although scientists are still trying to explain why glass is so solid, the belief that moving liquid and old windows down over time is unfounded.
And Buzz Aldrin\'s flashlight.
On 1999, Christie\'s east of Manhattan auctioned a variety of space souvenirs, including the flashlight used by Buzz Aldrin during the Gemini 12 space walk on 1966.
Auction catalogue mentioned: the flashlight lens is deformed in a vacuum.
I saw the flashlight with my own eyes.
The lens must be deformed, just like the glass flow.
It did not break. It’s deformed.
So I was cheated. I was in an article for abc News.
Com, \"provides convincing evidence that glass is really very slow
The liquid flowing, not solid, the thick lens of the flashlight is distorted by the powerful sucking force of the vacuum.
\"On the Bad Astronomy blog, Phil Plait took me to the mission because he called the Glass liquid. (
He also didn\'t like how I described the glass as being vacuumed out, and he thought it would be more correct to say that the air in the lens would blow the glass out. )
But Phil admits he doesn\'t know what caused the glass to deform.
He invited readers to provide more information.
As far as I know, no one has done so.
In covering my glass article, I showed a photo of the flashlight to several researchers.
They also don\'t have any good explanations to provide.
If nothing else, it shows that the nature of the glass still bothers a lot of people, even those who are really smart.
As I wrote in the article, there is no magic dividing line between liquid and glass.
However, any flow in the daily glass, if it does flow, will not be noticeable for millions of years of geological time scale. (
Ask a glass theorist: \"Would Glass flow if you waited millions of years?
\"You often get a very philosophical reply that you want to know if you have really asked God\'s nature. )
The flashlight sold for $9,000.
Comments are no longer accepted.
I\'m assuming that creating a sufficiently large differential pressure on a piece of glass on Earth will cause the glass to break.
I also suspect that if the glass has any obvious effect, the cold temperature of the space will cause the glass to be harder rather than softer.
The biggest problem seems to be what other factors (s)(
Assuming my assumption is correct)
The difference between the Earth\'s atmosphere and the space atmosphere may explain the expansion of the flashlight.
I suspect such an answer will appear here, but now my curiosity really wants an answer.
Please forgive my doubts, . . . . . . Are you sure the lens is glass? Does the deformation form when the flashlight is exposed to a vacuum?
If both cases are true, then I suspect this is a thermal effect.
This is an incandescent lamp, and the temperature of this lamp will be very high.
Heat from the filament flows through the air inside the bulb to the glass, through the glass, and then from the glass to the surrounding environment.
When the flashlight is in the atmosphere, the heat transfer on the outer surface of the glass will be dominated by convection and diffusion.
In vacuum, both heat transfer mechanisms do not exist, the only heat transfer on the glass surface comes from radiation heat transfer, and the total heat from the flashlight will be greatly reduced.
Therefore, the glass of the bulb and the air inside the bulb will heat up.
Heating the glass will soften it.
Heating the air inside the bulb increases the pressure.
The combination of these two effects leads to deformation.
Ack just saw a typo in my post
In the atmosphere, the heat transfer away from the outer surface of the glass will be dominated by convection and conduction.
This is what I posted at 1: 30 a. m.
An experiment on Earth is to put NASA\'s space flashlight with the same glass lens in a vacuum chamber with temperature control, exposing it to the same temperature, pressure and may provide insight into its condition as the Aldrin flashlight, but may still not be able to answer questions, ways and reasons.
I agree with Phil Plait that the deformation of this lens does not prove that the glass that is far below the temperature of the glass transition is still liquid.
It is likely to answer this question by considering what is seen in the photo and considering alternatives.
We saw in the photo that the glass was thin.
Many solids and glass go through a plastic deformation process called creep without exception.
Creep was found in many fiberglass failure experiments, measuring strength before forming or expanding suitable defects resulted in failure.
It also exists in the film and is also shown in the molded glass panel for flat panel displays.
In fact, most of us may not know this, but you can find this feature of glass in most plastic beverage bottles.
Many of these bottles have a thin layer of glass on the inner surface.
The layer is considered a coating, but deformed during the manufacturing process, deformed during the filling process, but does not fail because the film can creep.
Why is Buzz Aldrin walking in space with a flashlight?
So he can avoid snakes?
Thank you for eliminating the concept of glass flow in medieval glazing.
It\'s really wrong that you call it \"bunk\", but I don\'t know if it\'s going to be considered a real \"bunk \", because no one really uses this old concept as an example of the flow of glasses . . . . . . At least that\'s not the case anymore, although it\'s easy to see early researchers and craftsmen who might have regarded it as gospel, because they actually know how the glass is made from batches that are gradually melting from the increasingly hot mixture, just like its final terminal application, of course, you can see and feel the frozen streamline in the glass.
It is only when a larger, more objective, more scientific, that this is a natural assumption that will be overturned (
In the modern sense)
The inspection of the old Windows shows that in the design, there are a lot of old pieces of glass, the top is thicker than the bottom, the most likely reason is actually the bottom is thicker, because the process of making stained glass windows involves the craftsman making a decision by holding the glass, comparing it with the design to obtain applicability, arranging it for the sake of aesthetic and structural integrity, therefore, the thicker part will naturally rest more stably on the reclined easel, place the design on this easel and use it as a guide for the manufacture of lead glazing.
The thickness of the bottom, unless there is a complex reason why it is not placed like this (
Color or available shape)
I\'m still fascinated by the astronaut\'s flashlight.
I wonder if lense itself is in the boro family
Like pyrex or other low silicon glass
An extended formula designed specifically for its intended range of extreme conditions.
I suspect this is the case, when exposed to strong sunlight, lense becomes soft due to heating without being weakened by the atmosphere, may even be doubled by the geometry of the Sun Lense itself has a relationship with the position of the sun for a period of time, or may be some kind of invisible impurity that is not seen by the naked eye, or some sort of density arrangement as an internal refraction region.
Usually, if there is something common in the equipment and conditions of the space, it will make the most common glasses, but if it is lowthermal-
Expanded glass like boro
Glass, which can withstand heating and more critical cooling without cracking.
Bubbles in the lens may indicate \"sublimation \"(
Direct transition from solid to liquid)
In a vacuum in space, from glass to liquid.
Before answering this question, I would like to know the properties of the glass lens.
I think the solution is here.
Of course, the law of heat transfer must be used in addition to material properties.
About Amy (#2 & #3)
Comments on the heat transfer process at work, I agree with the comments that radiation heat transfer dominates in outer space (
When considering the heat transfer from the object to the surrounding vacuum. )
But we must also consider how the glass itself is heated.
It is presumed that it is more or less heated evenly by the infrared energy emitted by the Heat wire of the lamp.
When this happens, the process of conducting and radiating heat transfer will act as a cooling glass.
Also, I like to comment on the relative importance of radiation cooling and convection cooling of objects in normal environments.
Because radiation cooling will soon dominate as temperatures rise to fourth power.
This one looks easy.
If the glass \"flows\" due to the differential pressure, the process should be reversible when he restores the lamp to atmospheric pressure.
What is the definition of deformation? Its simple.
Aldrin uses the lamp and the bulb heats the glass, causing \"to flow faster\"e.
Become more plastic and more susceptible to pressure difference.
It does not restore shape because he turned off the light before returning to the ship.
Obviously, it was very hot by looking at the photos.
Given that Buzz Aldrin is still alive, he should be able to comment on the history of the use of light.
While one might say soon, well, that was 42 years ago, I would argue that walking in space must not be easy to forget.
Items I will consider: the composition of the lens glass.
This will certainly help to make any practical interpretation of such a serious deformation. Exposure.
It also depends on the composition.
If the glass is \"wet\" or has some hydration mass and is then exposed to microwave radiation (
Transmitter to Houston)
The glass \"could have\" absorbed enough heat to reach the softening point in a few minutes. (
Duration of space walk? )
The bulb theory works, but you will want to know that the bulb itself is not inflated (
Creep is of course a phenomenon that can be observed in glass, and when creep occurs in other materials, such as metals and ceramics, it is not surprising when you start to look at the glass at close range.
Inter-grain region of Crystal Growth (
You will have particles in any polycrystal material, which must have boundaries)
These molecules tend to be amorphous and do not fully align with any adjacent crystal.
This is the home of creep.
A cup, maybe add weight to the doctor
Wolynes theory is a family of metal glass, but it is the opposite.
To form a metal glass, it must melt faster than molecular crystals.
So when you shorten the time to get close to the infinitely short cooling, you maximize the entropy and become a material that likes sorting very much.
Metal Glass is one of the most interesting materials, but it may take decades or more for them to be manufactured in bulk.
They make steel-
What Liang did for the modern world: change it.
Thanks for the story of the flashlight.
In your main article of July 29, I would be happy to hear from real glass scientists, such as at any of the following institutions: University of Rutgers, Missouri --
University of Leeds, University of Saint Laurent.
University of St. Petersburg and Alfred, Russia (my alma mater; B. S.
Glass Science (2006).
My point is that any substance that shows bonds between the main molecules that make up the said substance is solid.
But solid state.
The graphics in your article just illustrate this.
Most of the flow in solid glass occurs between centuries or thousands of years and will not be recognized by humans if it is strictly at or close to room temperature.
The Deborah number of the glass indicates that the flow rate of the glass is more or less over time.
This is the reference of the Bible, in a way \"the mountain will flow like glass before the Lord \".
Although the object of comparison here is hot glass.
As we can see, the mountains do not flow.
Sorry, the reply time is too long! ! !
Once the lens is heated, it is likely to bend or be controlled by surface tension under the influence of external forces, and this distortion is not caused only by some pressure gradient, or even very significant.
Once the glass softens enough to move, gravity, pressure, or inertia is enough to create a twisting force.
The incandescent lamp in the device is the possibility of the heating reason is not very good for me, because if it can happen like this, I hope we can see it happening elsewhere in space lighting, I can\'t remember reading this book before.
One thing that the space environment does have is a very powerful electrical device that looks on the surface unaffected by human accidental contact, but the working environment in the space, like all work areas, tends to get complicated and chaotic, with a lot of potential for concentration, and I will include strong solar energy, especially in the space environment, when we experience it on the surface of the earth, 90% of the air is not filtered out by the atmosphere.
I can easily imagine that the flashlight may stay somewhere in the working space all the time, be illuminated by the sun, or in contact with the current conditions of formation, for a period of time, this will allow such a large amount of heating . . . . . . Keep in mind that the quality of the lens is relatively small, the vacuum and the glass itself are insulators, but it becomes conductive when the glass reaches a certain temperature, this can only be done in a relatively short time and distance.
The explanation of the deformed flashlight lens in the vacuum space assumes that the flashlight lens is made of glass and there is air in the flashlight. (
I don\'t know why there is air in the flashlight. )
A flashlight lens with pressure and temperature difference to help explain the deformation is also provided.
If so, then I have three questions :(1)
No windows (
If it\'s made of glass
On a spaceship, deformed, raised, or concave? (2)
Also, no windows (
If it\'s made of glass
Deformation, drum bag or depression of deep submersible?
Perhaps this phenomenon is avoided by having super thick or tempered glass.
But for the spacecraft, since weight is a problem, maybe some other stronger material is used for the windows of the spacecraft. (3)
Is the glass lens of the camera used in space also deformed? ? ?
Joe, the typical flashlight is designed like this, and the glass of the bulb does not get that hot during normal ground operation. (
Consider product safety. . )
It is well known that conduction and convection are the main heat transfer modes at low to medium temperatures.
At a mild temperature, convection dominates the heat transfer from the hot surface to the surrounding air.
In a vacuum, there will be no convection cooling on the outside of the glass, and when the flashlight is turned on, it will get hotter if the glass is running \"normal.
The heat transfer mechanism from the filament to the inside of the glass is secondary.
Whether the dominant mode is radiation or convection heat transfer, it will not change the root cause of glass heating.
The Incandescent lamp contains inert gas.
It extends the life of the bulb by suppressing the sublimation of tungsten wire. (
I said something wrong when I called this air.
I really shouldn\'t treat insomnia by posting on the blog. )
If my explanation is correct, then the glass windows on the manned spacecraft will not deform like a flashlight.
The interior of the spacecraft will be close to room temperature and the window glass will not become hot enough to soften.
The camera lens does not deform for the same reason.
Personally, I suspect that this deformed flashlight is purely a pressure effect.
The gas pressure inside the bulb is very low-
I suspect it\'s not just an atmosphere.
The differential pressure on the glass will be arranged in the order of 1 atm
Not very big.
As you have pointed out, this must be a problem in deep sea vessels, where the water pressure is hundreds of times that of atmospheric pressure.
The front edge of the surrounding hi-has no discoloration
The technical Fender material tells me the temperature required for the deformation of the glass (
Pure pedestrian definition)
The asymmetry of the deformed lens seems to indicate a high insulating power material with a narrower and lower melting temperature threshold.
If you want to take the time to wrap your flashlight into a carpet strip to avoid bumps and scratches, you can also consider using a broken polycarbonate lens.
Are we sure what this shot is made? [
No, I\'m not sure what this shot is made.
However, polyester is also a kind of glass material, so there is still a problem of how the lens is deformed. —Kenneth Chang]
I think previous posts about hot build combo-
The pressure difference may be on the right track.
I just thought it must have happened at a much lower temperature than the one needed to melt a normal glass.
My personal experience was in a glass blowing studio where I saw the hot glass charcoal wood and lit the fabric with a slight touch before it became hot enough.
I think that the pressure alone will break the glass lens, not deform it, and the amount of heat required to make the glass deformed to this extent will have some visible effect on the surrounding material.
Flashlights usually have light bulbs (evacuated)and a lens.
The light bulb is glass and the lens is plastic. (
Why it\'s called the lens is a mystery lost in the fog of time and the subject of another thread).
The bulb does get hot, but as the radiation cools enough, the bulb usually survives in a vacuum.
On the other hand, the plastic in the vacuum will not survive.
Still, there is not enough information to be sure here, and I suspect NASA has not noticed the issue.
There is no doubt that they are still using flashlights in space, a more suitable design!
Yes, I agree with what you said.
The radiation heat transfer from glass to outer space dominates the rate of overall heat loss and will determine the amount of heating up.
I put simple Stefan
Borzman\'s law for radiation heat transfer, and the temperature of the glass as an ideal black body medium is calculated (In infrared)
If it radiates at a rate of 1 watt per square centimeter.
I\'m sure the temperature is 648 Kelvin (
Or 375 C or 707 F).
It\'s quite hot.
It depends on my assumption.
In trying to figure out if the launch rate of the 1 W/cm ^ 2 I am assuming is too high or too low, I need to know the power of the light wire emission, the details of the parabolic face mirror, the most important thing is the properties of glass lenses (
The absorption/emission of radiation as a function of the wavelength. )
JoeGail calls the transition from glass to liquid \"sublimation \".
This is not sublimation, but melting.
Sublimation is a phase change from solid to gas.
I have been working with hot glass for a long time and I just don\'t think the lens is normal glass.
I really doubt it\'s glass.
There is a way to make a sculpture with glass called \"sliding\", which sounds like: a pile of glass is heated until it becomes soft and slides into a form.
This is a fairly long process that requires a lot of heat even for small pieces.
700 degrees Fahrenheit is about the temperature at which most glass softens, but when most types of glass harden again, it needs to cool down gradually to make the crystal structure stable.
Otherwise the glass will break.
The solution to this problem is not easy to find for me, which also seems strange.
There are external lights on the shuttle, and there are always lights on the suits of astronauts walking in space (
My understanding in space is that the area in the light is very bright and the area in the shadow is very dark).
Obviously, if the heat of a normal 6 Volt flashlight bulb can melt the glass, it would be a huge problem in space.
I know someone who works as an engineer in the aerospace industry.
I will ask him what he thinks about it.
No one mentioned the reflector inside the flashlight.
If directed directly to the sun, it should focus the light and heat of the sun on the bulb, but at a slight angle it may focus it on the lens.
If you stay there for a period of time while pointing to the dark side of the spaceship, the lens may become hot enough, at least partly softening the glass.
If the temperature is high enough, the movement of the flashlight may cause the softening glass to deform due to the inertia effect. You blew it.
Let\'s ask Alfie if he pointed the lens to the UFO he reported!
Let\'s say together he did it!
Wow, flashlight lens deformed by UFO!
Respected primo NYT science colonnist says all other scientific explanations are \"bunk \".
Let\'s see how far this \"fool\" chain is.
Released by Alan evil.
\"I have done quite a bit of work with hot glass \". . . . . . \"700 degrees Fahrenheit is the temperature at which most glass softens\" Allen. .
It\'s time to recalibrate your thermometer.
Even soft soda
Lime Glass is harder than most 987 of the rock. This is an excerpt from the Gemini 12 mission report (
Link from Wikipedia entry)
A penlights stored outside the tool bag on the adapter workstation shows signs of overheating.
The plexiglass lens has bulgedoward, and the paint near the lens shows a fingerprint that matches the paint marks on the EVA thermal gloves.
This penlight is exposed to the end of the lens and is most likely caused damage by direct solar heating.
The softener for the plastic lens material is about 190 degrees Fahrenheit. Ron Palmer[Thanks.
I think this is a very clear answer.
Just note: in the sense I wrote, organic glass is also a kind of glass (
Amorphous solid). —Kenneth Chang]
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