UA researchers discover that Einstein's laws of relativity determine the distance at which forces between two materials start acting
These effects are essential to quantitatively understand how molecular bonds are formed between atoms
Alicante. Friday 2 March 2018
A team led by researchers María José Caturla and Carlos Untiedt, from the University of Alicante Department of Applied Physics, have found out the mechanisms whereby two objects feel each other before “touching” and the characteristics of the contact between their first atoms. The discovery, which proves the importance of relativistic effects on long-range interactions between objects, has been published in two articles from the American Physical Society's flagship journal Physical Review Letters.
In this sense, UA researchers discovered that Albert Einstein’s laws of relativity determine the distance at which forces between two objects start acting. “It is surprising to see how Einstein's special relativity influences everyday processes, such as the one whereby two objects touch. We proved that due to this effect, heavier elements, for instance gold, exert forces on others at longer distances than one would expect if it were not for special relativity”, head of the UA Department of Applied Physics Carlos Untiedt explains.
These forces are highly important to understand a variety of processes around us, like chemical reactions or friction. Therefore, the UA researcher points out that “these effects will be essential to quantitatively understand how molecular bonds are formed between atoms”.
According to the UA Department of Applied Physics, “Einstein’s theory of special relativity is useful to plan space travels and plays a key role in everyday tasks; for instance, it enables GPS systems to accurately calculate positions”. In fact, Mr Untiedt argues that “Einstein’s relativity is relevant in cosmic or global phenomena, but it is also fundamental when it comes to understanding certain properties of matter at a microscopic level: as elements in the periodic table become heavier, electrons move around the nucleus faster and faster and reach speeds at which relativistic effects cannot be dismissed”.
This is the case of gold, with an electronic structure similar to those of silver and copper, but a considerably greater atomic mass. “Relativistic effects are therefore greater in gold and determine many of its properties as, when its electronic properties change, relativity affects atomic bonding, among other things”, the UA researcher explains.
“In our study we have proved how relativity affects the way two gold electrodes come into contact with each other. To that end, we have measured the distance at which a single atom of a metallic electrode is attracted by a second electrode approaching it”, Mr Untiedt adds.
These experiments allowed researchers to find out that, in the case of gold, electrodes interact at much longer distances than when silver or copper are involved. “With the help of theoretical simulations, it was proved that the attraction between gold atoms at long distances is mostly explained by relativity”. In summary, University of Alicante researcher Carlos Untiedt emphasises, “we proved the influence of relativistic effects on the mechanical properties of metals at a microscopic level”.