September 28, 2011

Can neutrinos travel faster than light?

Scientists in Europe claim that they have observed neutrinos traveling faster than light. What are neutrinos? Why is it surprising that they can travel faster than light? What’s the big deal?


What are neutrinos? They are sub-atomic particles – little wisps of almost nothing, with no electrical charge. Being neutral, they are found nearly everywhere and can pass through matter unabsorbed. If you hold your hand toward the sunlight for one second, about a billion neutrinos from the sun will pass through it.

These “ghost particles”, as they’re often called, are part of the universe’s essential ingredients, and play a critical role in helping scientists understand some of the most fundamental questions about the nature of matter and in crafting a picture of how our universe formed and evolved.

“Whence this creation has arisen. Perhaps, it formed itself, or perhaps it did not. The one who looks down on it in the highest heaven, only he knows, or perhaps he knows not” – A hymn from the Rig Veda

A group of scientists working at CERN (European Organization for Nuclear Research) – among other things – have been attempting to measure the velocity (or speed) of neutrinos, by shooting these particles through an “accelerator” (sort of a long tunnel built underground). In their experiments, the group found that neutrinos were arriving at their destinations earlier than expected. Startlingly, they appear to be traveling faster than light itself. No definitive conclusions have been drawn yet. The results will have to be examined by a wider group of scientists before they can be confirmed or deemed wrong.

Speed of Light

If we were to view the exquisitely intricate design of the universe as a “program” with some of the parameters as “fixed, constant and coded in” and everything else as “variable, relative, dynamic and subject to change”, the only constant (that we know of) is the speed of light (‘c’). Why is the speed of light constant? It just is. We don’t really know why. And light travels at slightly more than 186,000 miles per second. All we know or can say in this regard, is that our measurements till date have not disproved that assertion. It’s the way things work in this particular version of the universe that we find ourselves in, to the best of our knowledge. That light never slows down or comes to a rest and is always moving at a constant speed. This assertion forms a critical basis for Einstein’s Theory of General Relativity.

Einstein’s Theory of General Relativity

The simplest way to explain this is to say that “nothing is absolute” or “everything is relative”. So, immediate answers to any question posed are “it depends” and “compared to what?” For example, a train said to be moving at 60 kmph is relative to a stationary observer on a platform, and not relative to another observer on another train moving in (say) the opposite direction at 70kmph. Everything in the universe is in motion or at rest, *relative to something*. Galaxies with their stars are racing, planets and moons are revolving and rotating and indeed the universe itself is expanding. Grossly simplified, the theory of general relativity is a framework that explains everything as relative and subject to a frame of reference with the notable exception of two things – the speed of light and the laws of physics themselves – which hold steadfast no matter whether you are in San Francisco or in some dark, uninhabited corner of the universe.

Einstein’s theory of general relativity is magnificent for many reasons. In particular, it is awe inspiring for the reason that it tells us that “time itself is relative”. Time itself moves faster or slower depending on the velocity of motion, a mind boggling notion. Clocks slow down when you move faster. Of course, this is not noticeable at speeds we humans move around at normally. The “time dilation” effect kicks in only when we can get to speeds resembling that of light.

Why the fuss about the CERN finding?

It’s tough being a sub-atomic particle these days with scientists constantly tracking your every movement and accusing you of some misdemeanor or the other. If it turns out to be true that neutrinos have been caught breaking the “speed limit of the universe”, the implications are profound at a fundamental level. No, it will not change the way we live in any way. The sun will still rise in the east. Our lives will weave their ways inexorably through to whatever lies ahead. We will continue to fight our daily battles, wage our petty wars and live our lives ordinarily as we did yesterday and the day before. It won’t tell us if there is a God who designed it all. It won’t tell us otherwise either. Yet, everything would have changed. Einstein once said “Time is just a mechanism that ensures that everything doesn’t happen all at once”. The future is nothing more than where light has not reached as yet, or in other words a past that is yet to happen. If something is found to travel faster than light, then notions of past, present, future, time, cause, effect, etc. become mysteriously murkier than ever.

But, it will add a smidgeon of hope and joy that we would have inched forward in the quest for knowing. It will tell us that there is more afoot, more thrill to be had in this pursuit, and simultaneously give us pause to examine this wonder that we call life.

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