The light from the outermost observable universe has taken 13.8byrs to reach us. This consitutes the radius of the observable universe. In this time the universe (assuming at least uniform expansion) would be at least 27.6byrs in radius by now in relation to our current timeframe (although likely to be much bigger due to acceleration…and naturally unobservable by us).

Throughout earth history it has not exactly always been that hospitable though; only over the past 0.5byrs have we seen explotions of life.

The basic fact is real enough though, we as a race HAVE to venture into space for our long term survival. So if you wish to see the human race survive well into the future there can simply be no argument to space exploration and colonisation of other worlds. QED!

The light barier is not an obstacle to space faring either.

And please be so kind as not to insult astronomers. They are by far the best and most useful scientists that current and future mankind will depend upon….(them and the rest of the physics and engineering community of course!)

Firstly, it does not take an observation of the backside of the moon to prove that the moon is not a disc, but a spheroid (it’s not a sphere). And the ancient Greeks did it. With the math and science they had available to them at the time. (They also demonstrated that the earth was round without needing to circumnavigate it).

Secondly, although we could not observe the far side of the moon in the past, observation of the the far side of the moon was not unobservable in principle. Nothing in the science of Newton (or even Aristotle) ruled out a potential observation of the far side of the moon. Thus, speculation about the far side of the moon fell within the purview of science, along with any speculation with respect to what sort of technology would be required to make that observation, and what kind of engineering would be necessary to build it.

Thirdly, dark matter and energy ARE observed. By their indirect effects on the movements of other objects, and the expansion of spacetime. ONLY because we have these observations are we able to hypothesize about them. And ONLY because we CAN observe them in this way do we even talk about them at all.

Fourthly, string theory may very well be wishful thinking. The jury’s still out. Many cosmologists have reservations about string theory and some really are arguing with conviction that it isn’t science. Many are insisting that string theory should not be considered science until the string theorists are able to propose theoretical means by which the theory can be tested.

What lies beyond the observable universe is considered unobservable because of the speed of light limit. In other words, based on our current understanding of the laws of physics, not only is it unobserved by present capability, it is theoretically completely impossible to observe by any means, ever. Even with infinite time and infinite resources and infinite cleverness and infinite power, we will never, ever, ever, ever be able to observe it, assuming relativity is broadly correct.

And something that cannot even theoretically be observed cannot be tested, even theoretically. If it cannot be tested, it is not science.

Well, for all practical purposes , “observable universe” = “universe”. That which cannot be observed does not fall within the realm of science.

(Not ruling out the possibility that someday some means might be discovered of observing what previously can’t be observed, of course).

What errors are you talking about? I assume one thing you think is an error is the use of “data is” rather than “data are.” If that is, in fact, what you’re referring to, you’re wrong to say we’re wrong. We’re well aware of the fact that “data” was originally the plural form of the singular “datum,” but it’s now perfectly acceptable in common English to use “data” with singular verb forms, like “information.” Oxford, American Heritage, and Merriam-Webster are all clear on this point.

Anyway, it’s pedantic to get all huffy over a point like this. But if you’re going to be a pedant, you’ll come off better if you’re actually right.

—Amos Zeeberg, Discover Web Editor

PS: “Grammatical” would’ve been better.