Skip to main content

HOW DO TRACTOR BEAMS WORK?

How do tractor beams work?

•Up until recently, tractor beams (beams of light that tow objects) existed only in the world of science fiction.

•While large-scale tractor beams that can tow space ships are still machines of the future, microscopic tractor beams are here today. 

•The idea at first seams to defy physics. Shoot light at an object and the light's momentum should push the object away from the light source according to the law of conservation of momentum; not pull it closer like a tractor dragging its cargo.

•But what if you managed to create a situation where upon striking the object, the light gains forward momentum instead of losing it. 

•In that case, the law of conservation of momentum tells us that the object will lose momentum in the forward direction, even to the point of going backwards, towards the light source.

•So there is a way to make a tractor beam without violating any physics, if you can get the light to gain forward momentum upon interacting with the object. 

•You need to the light to slingshot past the object instead of bouncing off of it. The most effective method to accomplish this feat at this point in time is to use solenoidal light beams.

•A solenoidal shape is like a wire wrapped in circles into a helix that forms a hollow cylinder. But in this case, there are no wires. The light itself, traveling through the air, is formed into this hollow, spiraling shape. 

•San-Hyuk Lee of UC Berkeley and his collaborators have experimentally verified that the solenoidal light shape indeed draws objects – in their case, microscopic glass spheres – towards the light source.

•They have therefore successfully created a real tractor beam. 

•You can think of the spiral-shaped light beam as a screw that twists the object up the beam.

•Only microscopic objects have been tractor-beamed so far because light carries so little momentum. 

•In order to tow large objects, you would need very strong light beams. So strong, in fact, that damage of the object may become a problem. Research is ongoing.

Comments

Popular posts from this blog

How Energy conversion from coal is done?

Single generator sets of over 600 MW are now used in the UK, though there are many smaller generators in use. A 600 MW generator can supplythe average needs of over 1 million UK households. Three or four such generators are typically installed in a single large coal-fired station which isoften sited close to a coal mine, away from the city dwellers who consume the electricity. Such generators are usually driven by a compound arrangement of highpressure, intermediate-pressure and low-pressure turbines, increasing in size as the pressure decreases. Modern turbines rotate in a speed range from 1500 to 3500 r.p.m., usually 3000 r.p.m. for the UK’s 50 Hz system. For large coal-fired plant the steam pressure could be 25 megapascals (MPa) with steam temperatures of 500–600 °C to improve the thermodynamic efficiency. In nuclear reactors, which operate under less demanding conditions, the steam is superheated to about 5 MPa and 300 °C. Modern water tube boilers are complex and have ...

How ASPs works?

The Web and the Internet began to really heat up and receive significant media exposure starting around 1994. Initially, the Web started as a great way for academics and researchers to distribute information; but as millions of consumers flocked to the Internet, it began to spawn completely new business models. Three good examples of innovative models include:   • Amazon - Amazon (which opened its doors in July, 1995) houses a database of millions of products that anyone can browse at any time. It would have been impossible to compile a list this large in any medium other than the Web.   • Ebay - Online auctions make it easy and inexpensive for millions of people to buy and sell any imaginable item. It would be impossible to do this at a reasonable cost or in a timely manner with any medium other than the Web.   • Epinions - Thousands of people contribute to a shared library of product reviews. One of the Web's greatest strengths is its worldwide view a...

All about Electronics & Instrumentation Engineering)(EI)

  Vision : To be globally recognized as a seat of learning and innovation in Electronics for application to Communication, Transportation, Defence, Industry, Health Care, Entertainment, and many other consumer products.  Mission : 1). To produce quality engineers in the field of Electronics and related domains.  2) To conduct research and develop products in the fields of Chip design, Communication Systems, Electronics Instrumentation, Signal Processing and other related areas with strong emphasis on critical state of the art applications.  3) To grow in the area of Design and Manufacturing of chips, boards and systems.     Program Educational Objectives :  I.  To provide students a successful career in industry that meets the needs of national and multinational companies.  II.  To develop the ability among students to synthesize data and technical concepts for application to electronic product design and to solve real...