Studies Say Earth Won't Die As Soon As Thought 155
sciencehabit writes "Take a deep breath—Earth is not going to die as soon as scientists believed. Two new modeling studies find that the gradually brightening sun won't vaporize our planet's water for at least another 1 billion to 1.5 billion years—hundreds of millions of years later than a slightly older model had forecast. The findings won't change your retirement plans but could imply that habitable, Earth-like alien worlds are more common than scientists thought."
Where is everybody? (Score:4, Interesting)
It's an input to the Drake equation. That's worth looking at again. When Drake wrote it, most of the numbers were guesses, but we now know that exoplanets are not rare.
I suspect the reason we haven't heard from anybody is that the lifetime of high-power technological civilizations is only a few hundred to a thousand years. We're only about 200 years into industrial society, and we've already burned through most of the easy to get natural resources.
Re:Where is everybody? (Score:5, Interesting)
If you think the uplinks to the Geostationary satellites are low power and dont spread out, you really dont understand RF or satellite comms. Some of the older TV birds up there are almost deaf, so we are BLASTING 100,000 watts of energy into a 25 to 30 db gain antenna to hit them. when the signal hits it, it is not 3 inches around and fits nicely in the receiving antenna, it's about 5 miles across, and will continue to spread.
Here is the problem. Radio waves drop in strength Logarithmically. Which means even a 100,000 watt tightly beamed RF signal will be barely above the noise floor before it even get's 4X the diameter of our solar system away. When they talk to Voyager 1 or 2 they are using the largest dish antenna on the planet, and then they are blasting an ungodly amount of power to barely reach it. They also are using the 8GHZ band that has a very low noise floor and almost no interference within a lightyear.
Voyager has a 23 watt transmitter, but a large gain antenna focusing it at earth, but it requires the massive 1000 foot dish or a huge array of smaller dishes to barely receive it. and not much longer, we will not have an antenna with enough gain on this planet to receive it's signal any longer. within the next 4-5 years we are expected to lose all contact with Voyager 1. And this thing is just in out back yard a few feet from the house.
Even if an alien race knew where earth was exactly, and had a 1000 foot dish antenna with a 10Terawatt transmitter pointed right at us. If they were not within a 20 lightyear radius of the earth, their signal would not reach us at a strength that we could detect today.