Scientists at the University of Glasgow have successfully slowed down the speed of light travelling through the air.
The original article at the University of Glasgow site can be found here :
We have long since known you can slightly reduce the speed of light as it travels through objects as the article says such as water or glass. Photons which make up light however should remain at a constant "light speed" when travelling through "free space" (no interacting with any materials).
This term "Light speed" is a universal constant who we can all pay great thanks to Albert Einstein for essentially figuring it all out for us lol (You can see an excellent recent documentary on Albert Einstein and his Theories of relativity here). However other phrases such as "Light year" are based on this constant.
A light year essentially is the total distance a single photon of light can travel uninterrupted in free space at its universal constant of "Light speed".
So what does this really mean (beyond what the article clearly points out in normal everyday life - nothing lol)..
However bigger forces are at work here. If a "Light year" is no longer a constant then that is the same as saying a Kilometre is about 950-1100 meter-ish, it just doesn't make sense.
To give an example based on something you may of learnt in school!..
If you look at the stars at night it could be the case some of them little specks of light are stars long since dead. They are so far away that the distance the light has travelled to hit your eyes is so vast it took many (super simplified!) years to reach Earth for you too see it.
This is actually a basis in science in which great distances can be calculated based entirely on light measurements in various ways. The techniques and methods are not the point as all base very complicated algorithms based on what we assume to be universal constants. What you must always remember is that our scientific understanding of light is far from complete. What we are able to achieve now is only the beginning and therefore it's entirely plausible to predict that photons can be slowed even further than what we even think possible.
While all being speculation if you take it further then all our understanding of the size, speed, rotation of the entire universe would be off by a large factor.
Everything we do on earth that effects and changes our current understanding of nature and physics often we end up discovering in nature itself or in the universe. I would go as far to say that somewhere out there is a gas giant in space that has the principle effects that the scientists in Scotland emulated but on a larger scale, if that where true then all light from that region of space would be greatly effected on it's long journey to us. That would mean in for example a Hubble telescope image there would regions or "pockets" of space where light has been greatly distorted emulating in effect a "time warp distortion" where light has travelled at different speeds bringing in essence different moments in time to ourselves all at the same time.
Good luck finding that.. If I'm right then I'm glad I'm not the one working on the algorithms to detect such anomalies!
The flip side
There is another side effect that is potentially when technologically able will benefit all mankind. If light can slow down then I would bet it can also increase in speed even if by the smallest margin. This would mean travelling past light speed in such a way that "normal space" would appear to seriously look like something out of star trek!
Think of it like a horse race where during the final leg of the race the lead horse sprints to victory leaving the others behind all at different positions at different speeds. If you could sit on that horse looking backwards you would see the horses drop back getting smaller as you accelerate.
This would be the same of an object manipulating light speed past the known constant, what you observe would be the stars increasingly dropping backwards while light ahead of you seems to stretch as a blur. Confused? Here's a simple comparison:
Almost everyone has been in a car going down the motorway, you watch the road lines with spaces between them going fast. Faster you go the more they seem to "connect".
Is this time travel?
NO! I 100% do not believe in such fairly tails. In theory if you could calculate the refraction of light reflecting of the Earth back into space and travelled in the same direction at beyond light speed then it's plausible to view events in the past. However if I need to explain how complicated such would be then I'll have to write a new blog just for it lol.
Visa versa to go forward in time would imply increasing the rate of which all things in the universe act so erm.. no. You can't go view events based on manipulating time which itself is nothing more than a definition created by humans to describe the passing of "time". As a form of measurement that is like trying to go back in meters, litres or volume.