Scientists Find That Conditions For Life May Hinge On How Fast the Universe Is Expanding (sciencemag.org)

sciencehabit writes: Scientists have known for several years now that stars, galaxies, and almost everything in the universe is moving away from us (and from everything else) at a faster and faster pace. Now, it turns out that the unknown forces behind the rate of this accelerating expansion - a mathematical value called the cosmological constant - may play a previously unexplored role in creating the right conditions for life. That is the conclusion that a group of physicists who studied the effects of massive cosmic explosions, called gamma ray bursts, on planets made. They found that when it comes to growing life, it's better to be far away from your neighbors - and the cosmological constant helps thin out the neighborhood.

Comments

Re:As all are aware Einstein's math showed an expa

[ChromaticDragon]

You raise a worthy query.

But I'd like to raise a couple of concerns. First, you could just have done a quick websearch on "Cosmological Constant". The Wikipedia article alone is enough to answer your query although the math there might turn some away. Second, though, and much more concerning to me is this strange apparent deification of Einstein. The man was a decent scientist. But he was surrounded by and worked with many other incredibly talented folk. On many things he was correct. However, he was on the wrong side of many debates. One of the cool things about Einstein was that he was able to admit when he was wrong (though it may have taken a bit of time and patience for folk to demonstrate where and why he was wrong).

But the Cosmological Constant? Nah. That one is easy. He added it, as you've described as much because of what he wanted to be true rather than what evidence had shown to be true. But when he did so, the evidence wasn't so strong either way. Pretty much as soon as the evidence rolled in, he backed off.

So why is it back in play now? Well, you need to understand it's been back for years now. This aspect isn't new. The authors of this article don't need to defend it. Indeed, nobody really does. Why? Because more evidence keeps rolling in and now we know we need it. Evidence trumps theories.

But this isn't a binary thing. It's not off/on. It, at the very least, is negative/zero/positive. Einstein set it to a negative value. He'd hoped this resulted in a static universe. Now we know that even that isn't correct. It's static, but unstable. When removing it, he essentially set it to zero. This matched an expanding universe. But as the evidence kept rolling in, it's clear that the universe isn't just expanding - it's expanding at an ever increasing rate. To get that, you need a positive value.

Re:Cosmological Constant

[HybridST]

I'm not a physicist (oops - i mean IANAP) so the standard dose of salt should apply but i have watched many lectures online about many topics within physics. My understanding is that it really is the same term but used a bit differently.

Einstein favoured a steady state term(iirc he used gamma for it) in the equations for GR which was called the cosmological constant. Along came hubble who discovered the expansion of the universe and Einstein finally gave up on the fudge-factor term he had inserted to keep the universe mostly static..

60 or so years go by until scientists in the mid 90's discover that the expansion of the universe is accelerating contrary to most of their expectations. They reinstate the fudge-factor term but this time to represent so-called dark energy and it's effects on space-time.

That pretty much brings it up to date. For more info find Susskind lectures on all kinds of physics on youtube and on the Stanford site with a few honourable mentions in the repository of the Perimeter Institute's public lectures available at their site.