I recently discussed some the problems inherent to time travel in works of fiction. Most notably, the paradoxes contained in the Terminator and Back to the Future movies. But now I want to take a step back and look at time itself.

Does "time" even exist?

The standard notion of time is that it is a fourth dimension just as fundamental and intrinsic to the universe as the three spatial dimensions of length, width, and height.

But the truth is: time is just an abstraction of the human imagination. It is a convenient construct that we use to explain relationships between things in our universe. Like motion, time does not exist without the objects that we use as a frame of reference for measuring it.

Time is scientifically defined as a relationship to the rate of decay of a radioactive caesium atom. It is also often linked with the speed of light, which is often seen as a “cosmic speed limit”.

But is this view of time really necessary? Is time truly a fundamental property of our universe?

“What we observe is not nature itself, but nature exposed to our method of questioning”
   - Werner Heisenberg, father of quantum physics.

Today marks the anniversary of quite a few historical events of significance.

Today, the American Civil War turns 150 years old, as we observe the anniversary of the April 12, 1861 attack by Confederate troops of Fort Sumter near Charleston, South Carolina. Although a grim occasion on its own right, this attack does have some silver lining, as it began the conflict that would eventually set in motion this nation's steps towards racial equality.

50 years ago today, on April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human being to travel into space and orbit the Earth.

Today is also the 30th anniversary of the 1981 maiden voyage of the space shuttle Columbia, the world's first reusable spacecraft. It was a momentous and cheerful day for space exploration. The shuttle itself met a tragic end, when it disintegrated on re-entry during a mission, killing its seven crew and passengers over 20 years later. I'd like to take this moment to thank the brave men and women of NASA for the heroic work they do expanding the horizons of human knowledge and experience, and to offer my sincerest condolences to the friends and family of all such heroes who did not return.

In a paper published by physicists at the Fermilabs Tevatron particle accelerator in Illinois, researchers claim to have found evidence for a new fundamental particle outside the traditional Standard Model of Particle Physics that may represent a fifth fundamental physical force beyond gravity, electromagnetism, strong, and weak nuclear forces.

The paper, titled Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in ppbar Collisions at sqrt(s) = 1.96 TeV (arXiv:1104.0699v1 [hep-ex]), is a reporting of findings from a research project involving the smashing together of protons and antiprotons in an attempt to create new particles. The paper shows some results that are not predicted by the existing Standard Model of Particle Physics, and which (if confirmed) would mean that theory would need to be revised or thrown out altogether.

Yesterday, the space shuttle Discovery landed on Earth for the final time in its 27-year long career. On Monday, it has been reported that actor William Shatner gave the crew their final mission wake up call:

"These have been the voyages of the space shuttle Discovery, Her 30-year mission: To seek out new science. To build new outposts. To bring nations together on the final frontier. To boldly go, and do, what no spacecraft has done before."

Discovery, which has been taking astronauts into space since before I was even conceived, is expected to be donated to the Smithsonian Institute's National Air and Space Museum following a decontamination procedure. It will replace the space shuttle Enterprise, which will likely go on loan to other museums.