. Every one of us is a biomolecular computer,

8 FEB, 2012, 05.31PM IST, PTI

World's first 'biological computer' developed

WASHINGTON: Scientists in the US claim to have developed the world's first "biological computer" that is made from biomolecules and can decipher images encrypted on DNA chips.

A team from the Scripps Research Institute in California and the Technion-Israel Institute of Technology claims it has created the computing system using bio-molecules, 'Angewandte Chemie' journal reported.

In the research, when suitable software was applied to the biological computer, the scientists found that it could decrypt, separately, fluorescent images of Scripps Research Institute and Technion logos.

And, although DNA has been used for encryption in the past, this is the first experimental demonstration of a molecular cryptosystem of images based on DNA computing, say the scientists led by Prof Ehud Keinan.

"In contrast to electronic computers, there are computing machines in which all four components are nothing but molecules," Prof Keinan said.

"For example, all biological systems and even entire living organisms are such computers. Every one of us is a biomolecular computer, a machine in which all four components are molecules that 'talk' to one another logically," he said.

The hardware and software in these devices, Keinan notes, are complex biological molecules that activate one another to carry out some predetermined chemical work.

The input is a molecule that undergoes specific, predetermined changes, following a specific set of rules (software), and the output of this chemical computation process is another well-defined molecule.

But, what a biological computer looks like? "This computer is built by combining chemical components into a solution in a tube. Various small DNA molecules are mixed in solution with selected DNA enzymes and ATP. The latter is used as the energy source of the device.

"It's a clear solution - you don't really see anything. The molecules start interacting upon one another, and we step back and watch what happens. And by tinkering with the type of DNA and enzymes in the mix, researchers can finetune the process to a desired result," said the scientists.

Added Keinan in a statment: "Our biological computing device is based on the 75-year-old design by the English mathematician, cryptanalyst, and computer scientist Alan Turing."

Cosmology

Shortcomings of the Standard Cosmology

Despite the self-consistency and remarkable success of the standard Hot Big Bang model in describing the evolution of the universe back to only one hundreth of a second, a number of unanswered questions remain regarding the initial state of the universe.

The flatness problem

Why is the matter density of the universe so close to the unstable critical value between perpetual expansion and recollapse into a Big Crunch?

The horizon problem

Why does the universe look the same in all directions when it arises out of causally disconnected regions? This problem is most acute for the very smooth cosmic microwave background radiation.

The density fluctuation problem

The perturbations which gravitationally collapsed to form galaxies must have been primordial in origin; from whence did they arise?

The dark matter problem

Of what stuff is the Universe predominantly made? Nucleosynthesis calculations suggest that the darrk matter of the Universe does not consist of ordinary matter - neutrons and protons?

The exotic relics problem

Phase transitions in the early universe inevitably give rise to topological defects, such as monopoles, and exotic particles. Why don't we see them today?

The thermal state problem

Why should the universe begin in thermal equilibrium when there is no mechanism by which it can be maintained at very high temperatures.

The cosmological constant problem

Why is the cosmological constant 120 orders of magnitude smaller than naively expected from quantum gravity?

The singularity problem

The cosmological singularity at t=0 is an infinite energy density state, so general relativity predicts its own breakdown.

The timescale problem

Are independent measurements of the age of the Universe consistent using Hubble's constant and stellar lifetimes?

A Brief History of the Universe

The history of the Universe divides roughly into three regimes which reflect the status of our current understanding:

• Standard cosmology
• Particle cosmology
• Quantum cosmology

The standard cosmology is the most reliably elucidated epoch spanning the epoch from about one hundredth of a second after the Big Bang through to the present day. The standard model for the evolution of the Universe in this epoch have faced many stringent observational tests.

Particle cosmology builds a picture of the universe prior to this at temperature regimes which still lie within known physics. For example, high energy particle acclerators at CERN and Fermilab allow us to test physical models for processes which would occur only 0.00000000001 seconds after the Big Bang. This area of cosmology is more speculative, as it involves at least some extrapolation, and often faces intractable calculational difficulties. Many cosmologists argue that reasonable extrapolations can be made to times as early as a grand unification phase transition.

Quantum cosmology considers questions about the origin of the Universe itself. This endeavours to describe quantum processes at the earliest times that we can conceive of a classical space-time, that is, the Planck epoch at 0.0000000000000000000000000000000000000000001 seconds. Given that we as yet do not have a fully self-consistent theory of quantum gravity, this area of cosmology is more speculative.

Chronology of the Universe

The following diagram illustrates the main events occurring in the history of our Universe. The vertical time axis is not linear in order to show early events on a reasonable scale. The temperature rises as we go backwards in time towards the Big Bang and physical processes happen more rapidly. Many of the transitions and events may be unfamiliar to newcomers; we shall explain these in subsequent pages.

Orders of magnitude

The timescales and temperatures indicated on this diagram span an enormous range. A cosmologist has first to get the order of magnitude (or the power of ten) correct. Quantities which are given as 10 to some power 6 (say) are simply 1 followed by 6 zeros, that is, in this case 1,000,000 (one million). Quantities which are given as 10 to some minus power -6 (say) have 1 in the 6th place after the decimal point, that is, 0.000001 (one millionth). At extremely high temperatures we tend to use gigaelectron volts (GeV) instead of degrees Kelvin. One GeV is equivalent to about 10,000,000,000,000K.

Scientists create cloaking device that 'hides' whole events - making time itself disappear

Most of the human race don't have any problem making time disappear - but scientists have cracked a very hi-tech way of doing exactly that. 

Scientists have developed a 'temporal cloaking' device that can hide events from view.

The demonstration 'hid' events for 40 trillionths of a second - or 40 picoseconds - by speeding up and slowing down different parts of a light beam.

The different parts of the light beam were then put back together, so that any observers could not detect what happened during the 'hidden' time.

The information is simply not there to be read or reconstructed.

So far, the technique only works on periods of 0.00012 of a second - so the police can probably rest easy, as evildoers would have to move far faster than human beings ever could to 'conceal' their actions.

Instead, the 'hidden' fractions of a second could be used for ultra-secure communications.

The scientists think that the technique could even be combined with recent advances in optical 'cloaking' - to hide an event in both space and time.

 

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Professor Robert Boyd and Dr Zhimin Shi, of Rochester University in New York, reviewed the paper for the journal and said: ‘As if the idea of a device that makes an object seem invisible was not mind-boggling enough, researchers have now demonstrated a system that can conceal an event in time.

‘Because spatial and temporal cloaking work in different physical dimensions - space and time, respectively - there is no fundamental reason why the two techniques cannot be combined so that full spatial-temporal cloaking could be turned on or off at will.

In this 2011 illustration, provided by Cornell University, scientists demonstrate how they have have created, a new invisibility technique that doesnít just cloak an object but masks an entire event

‘Nonetheless, what Fridman et al. have demonstrated as a first temporal cloaking device could already be useful in some applications, such as enhancing the security of communication in fibre-optic systems.  

‘Future directions may include increasing the cloaking time towards the order of microseconds to milliseconds, and building a device that can work simultaneously for incident light coming from different directions.’ 

The demonstration 'hid' events for 40 trillionths of a second - or 40 picoseconds - by speeding up and slowing down different parts of a light beam

The effect is achieved using a split time-lens that breaks light up into slower and faster 'components' - thereby creating a tiny temporal gap. It works by compressing the light passing through a fibre optical cable with a special lens that causes some to speed up and some to slow down

They were able to conceal time for 40 trillionths of a second - or 40 picoseconds - by speeding up and slowing down different parts of a light beam.

Theoretically, anything happening in that tiny gap would be invisible and undetectable, because it would not exist in our perception of time.

The device could be used for ultra-secure communications - or, in one sci-fi scenario, could even be combined with an optical invisibility device, cloaking the user from both space and time, researchers say.

The effect is achieved using a split time-lens that breaks light up into slower and faster 'components' - thereby creating a tiny temporal gap.

Unlike other cloaking devices that work by bending light around objects, this works by compressing the light passing through a fibre optical cable with a special lens that causes some to speed up and some to slow down.

This makes the waves divide and another lens a little further up the cable then causes the light to be put back together.

The result is light emerging from the end of the cable that appears to be unaltered which means for the space between the lenses things have or could have gone on - with no record of it occurring.

Professor Moti Fridman, of Cornell University in New York, and colleagues said a 'time hole' in the probe beam hides the occurrence of an event from the observer.

They said: ‘This approach is based on accelerating the front part of a probe light beam and slowing down its rear part to create a well controlled temporal gap - inside which an event occurs - such that the probe beam is not modified in any way by the event.

‘The probe beam is then restored to its original form by the reverse manipulation of the dispersion.  ‘In summary we have presented the first experimental demonstration of temporal cloaking that successfully hides an event from a probe beam in the time domain.

‘Our results represent a significant step towards obtaining a complete spatio-temporal cloaking device.’ Physicists have already found ways to make invisibility cloaks by distorting electromagnetic fields and steering light around a volume of space so that, essentially, anything inside this space is invisible.

Prof Fridman's researchers were able to take that idea a step further and cloak time.

They built a device that has two lenses called an electro-optic modulator. Next, they sent a beam of light through the lenses. The first lens compressed the light, while the second lens decompressed it, leaving a short gap or hole, in time where any event went unrecorded.

To the naked eye, light coming out of the second time-lens appeared uninterrupted, as if no distortion had occurred.

In essence, between the two lenses exists a space-time void that cloaks any changes occurring in the short amount of time it takes the light to pass through both lenses.

If coded messages could be hidden in a series of these cloaks it would be very difficult to intercept them - making for very secure communications.

On the other hand if such a hidden time lag could be made to pulse on and off it could be used to intercept data passing through without there being a record of it.

And if the technology could be expanded in theory you could step between two lenses and do anything you wish and it would never be recorded in time - for the rest of the world it would never have happened.

But the researchers whose breakthrough is reported in Nature don't expect the technique could ever produce a gap that lasts any longer than 0.00012 of a second - not nearly enough time to do anything worth hiding.