Lava lamp
A lava lamp is a luminaire that uses the thermal energy released by an incandescent lamp to set a liquid in motion. The lights were popular furnishings for decoration in the 1970s and were rediscovered in the 1990s. The lava lamp was invented by the British entrepreneur Edward Craven Walker , founder of the British company Mathmos .
construction
The lamp consists of a bottle-like vessel under which a light bulb is attached. The vessel contains two non- soluble substances, both of which are liquid at operating temperature and have a similar density , but have different coefficients of thermal expansion .
For example, combinations of ( hydrophobic ) wax or oil with ( hydrophilic ) isopropanol or ethylene glycol , possibly mixed with water and salts to increase the density, are common . The addition of the appropriate colorants results in the eponymous lava or magma appearance.
The contents of the vessel are both illuminated and heated via the incandescent lamp (with some models also a tea light ). The wax becomes viscous. The ascending and descending of one (mostly hydrophobic) substance is due to its greater thermal expansion . When heated, its density is reduced more than that of the other liquid. This creates a static buoyancy that causes the fabric to rise in the form of large bubbles. The cooling in the upper part of the vessel reverses the effect, the liquid sinks again and the cycle begins again.
The substances used in some lava lamps such as benzyl alcohol or (formerly) carbon tetrachloride are harmful to health, a defective lava lamp should therefore be disposed of properly.
business
Depending on the model, lava lamps need 30 minutes to three hours to heat up and should not be operated continuously for more than eight hours to avoid damage.
history
The physical laws of the different spatial thermal expansion of different substances, which form the basis of the function of the lava lamp, have been known for a long time and are one of the phenomena that are constantly being rediscovered or explored experimentally. An excerpt from a book that is now over 100 years old will serve as an example:
“In addition, CR Darling described an experiment in which a vessel filled with water, heated from below to about 80 ° C, was used and aniline was poured into it. At a temperature around 63 ° C, aniline has the same specific weight as water. As the temperature increases, it expands more than water and is lighter the hotter and heavier the colder it is. The aniline, which soon collects as a large bubble on the surface, cools and the bubble sinks to the bottom of the vessel, where it heats up again. Soon afterwards, new bubbles form there and rise to the surface. This process continues indefinitely if the conditions remain the same. It is interesting to observe the bubbles, which are constantly changing into new formations. "
Sometime around the time of the Second World War, the Englishman Donald Dunnet is said to have tried to develop an innovative egg timer using the principle described. It is not known whether this domestic help was ever completed. But it is certain that a forerunner of the lava lamp designed by Dunnet found its way into the Queen's Head Pub in the New Forest , England as an eye-catcher .
Around 1950, the Singapore- born Brit Edward Craven Walker discovered a fascinating lamp in this very pub, in which one of the two liquids it contained was in constant motion. Walker took on the idea to develop a version from it according to his own ideas. What is certain is that in 1963, after years of development work, Walker founded the company Crestworth Limited , later Mathmos , to sell the lava lamp, which has now been named "Astro Lamp" . However, the renowned London department store Harrods was not interested in the innovative product.
Two entrepreneurs from Chicago , Adolph Wertheimer and Hy Spector, discovered Walker's lava lamp at a product fair in Hamburg in 1965 and acquired the manufacturing and sales rights for the American market. Craven Walker remained a technical advisor to her company. After their return from Europe they founded the "Lava Manufacturing Corporation, Chicago, Illinois", named the product "Lava Lite" and started the production and sales of a first series of models. From the Lava Mfg. Corp. later became Lava-Simplex Incorporated due to a change of ownership.
In the late 1960s and early 1970s, the lava lamp became well known. It has been a cult object ever since. At the beginning of the 1980s, however, the lava lamp experienced a downright depression. The sales figures fell sharply worldwide. As a result, the recently renamed American company Lava-Simplex International became the property of Haggerty Enterprises . In the late 1980s, Crestworth Ltd. shrunk to the size of a family business. Compared to the million-strong production figures of the 1970s, the production of a few tens of thousands of lamps per year seemed modest. The New Age generation lava lamp was known under the product name The Wave and was also sold in the USA by a Haggerty Enterprises company.
At the end of the 1980s, Cressida Granger , who also sold used lava lamps on her London flea market stand, noticed that the demand from a new generation of customers was steadily increasing. First she got in contact with the Crestworth company to secure supplies for her stand. But she soon recognized the coming retro wave. Instead of opening a branch store as originally planned, there was a meeting with the "father of the lava lamp" at which Craven Walker had a lucrative offer for Granger and her business partner David Mulley: He offered the two of them 20 percent of his company for them to bring it back into the black. If successful, the respective partnerships should then be swapped, so that Granger and Mulley would become the main owners of the company. A new company was formed, Crestworth Trading Limited . Later, as part of modernization measures, Granger changed the company name to Mathmos, the name of the lava-like bubbling lake of absolute evil from the 1960s cult film classic " Barbarella ".
In the mid-1990s, the lava lamp was in as much demand in the USA as it was in its heyday. Haggerty Enterprises founded the subsidiary Lava World International. Mathmos added a new model for the new millennium with the “Fluidium” to the product series in 2000, but even this did not stop the coming end of the retro trend. In the meantime, magma luminaires from the Far East were on the advance and flooded the market worldwide.
The two big patent holders, Mathmos and Lavaworld, have more or less divided the market among themselves. Lavaworld in particular strives to revitalize the market again and again. Among other things, they regularly offer special editions that are in great demand, especially among collectors, because they are mostly limited. But third-party providers can still find their sales markets.
Applications
The SGI company built a random number generator with six lava lamps . The lava lamps were used to generate the seeds . This was patented under US Patent 5,732,138
Individual evidence
- ^ Translation of an excerpt from Charles Vernon Boys' "Soap bubbles, their colors and forces which mold them" based on his earlier readings. The original manuscript was first published in 1902 by the Society for Promoting Christian Knowledge.
- ↑ Eric Hildebrandt: Quantum Optical Random Generators Methods and Analyzes , doctoral thesis University of Frankfurt, 2002, accessed March 23, 2015
- ↑ Patent US5732138A : Method for seeding a pseudo-random number generator with a cryptographic hash of a digitization of a chaotic system. Applied on January 9, 1996 , published on March 24, 1998 , applicant: Silicon Graphics, Inc., inventor: Landon Curt Noll, Robert G. Mende, Sanjeev Sisodiya.
- ↑ to 2001 as an online random number generator via lavarand.sgi.com ( Memento from May 21, 1998 in the Internet Archive ).
- ↑ The Generation of Random Numbers from Das Mathebuch , Clifford A. Pickover, Librero, 2014, ISBN 978-90-8998-280-3
