ahhhh yes, i've always wanted to reply to this forum.
Well to me, I have several theories pertaining to how mankind will end, and yes, it'll end brutally, regardless of whether you believe in a religion that states "no man should die, nor suffer in vain". Welcome to science.
The sunEvery star has a cycle. Right now our sun, a star, is now an average sized star, think of it as a middle aged man. The Cycle: Every star forms in a dusty soup of particles and gases known as a STELLAR NEBULA. This nebula can take two routes, morph into an average sized star, or morph into a massive star (Note this is not dangerous, this is just the main sequence). Then those 2 stars take their routes as main sequence stars. In this case, our star is in its main sequence. Billions of years there after, our star begins to lose it's precious fuel source, HYDROGEN. Now the massive star then morphs into a Red Supergiant, and the average sized one turns into a SuperGiant. Once they both run out of fuel, the red giant will blow up into a planetary nebula, and the red supergiant will blow up into a supernova. The Red Giant will finally rest in peace as a white dwarf, whereas the Red Supergiant has the ability rest in peace as a black hole, or a neutron star. There you have it, our planet will abruptly end in 4-6billion years.
ClimateRather than waiting 4-6billion years for the sun to burn out, we can have the climate pwn us in a matter of milleniums, or hundreds of years. Studies show that Florida will be 10 ft underwater in 50 years, and venice is already gone. Global Warming is melting the polar ice caps, increasing the water levels of both the atlantic and pacific, as well as the indian ocean. We're really commiting suicide here. Also, the Amazon Rainforest is what absorbs 1/3 of the carbon dioxide in the air, without it, CO2 levels will rise incredibly, but we're cutting it down at an ernormous rate.
Asteroid Apophis It was named after the god of darkness and chaos, in egyptian terms. Apophis has a good chance of hitting earth in april 13, 2029. If it does, then it'll destroy california. If it intends to miss it's target, beware, it'll come back with a vengeance. If it misses california, then it's likely to pass a gravitational keyhole, in which it could turn around and get another shot at us, but this time, falling in the pacific ocean, which will cause more chaos, for the nations that border the pacific. It will cause tsunamis over 100ft high, and it'll create a pressure increasing pulse, therefore, ensueing in a chain of earthquakes, and volcanic eruptions. Not only japan and california are gonna get pwnt by a tsunami, its likely that they'll encounter high richter scaled quakes.
for more information, read these two articles by NASA
http://www.space.com/scienceastronomy/asteroid_risk_041224.htmlhttp://www.space.com/news/051103_asteroid_apophis.htmlTake a look at thise picture. Look at apophis's orbit, and earth's, two chances of it hitting us.
Here's another image. That's Cali right there.
Theres several ways of avoiding this, but seeming as to how we lack natural resources, we're only limited to a couple of ways to eliminate the target.
Magnet Ship
A giant ship is to be created to attract the asteroid, and pull it away from earth.
Large amounts of fuel, and alluminum, and really giant magnet.
Rocket Nuke
Man... you're gonna need millions of tons of explosives to pull this off. Also, this could create more chaos for earth. As mini asteroids could spray all over earth, some the size of cities. Also, the miniasteroid would have radioactive waste on them, so ya, its really worth it.
Technology
Seeming as how we need technology to thrive, soon or later, technology would thrive on us. If we were to make a a robot, do almost the very samethings on our hands, then we have a catastrophic technobot on our hands. But its least likely we're gonna be killed by bots.
Quote from OnerayI noe you said i can't say that the human race will never end, but in reality, it can't. No virus can kill all humans because there are always a select few who are immune to the virus. Maybe if we get hit by an asteriod right now, but other than that, we well survive. Even if the earth is destoryed in the next 100 years, we probably would be living somewhere else. We would have colonies all ova the galaxy. Also remember, we can always crossbreed with other life forms or aliens.
Viruses have the ability to mutate faster than we could produce a vaccine for them. As a result, millions of people die from a disease without a proper vaccine. Russians made a hybrid virus, that was able to kill off thousands within a week. they only tested this on animals, thus, it was effective against humans, this was during the cold war. Cloning humans aint an answer to our problems, it costs money, and coloning thousands is very expensive, thus, it would create ethnic and racial problems in humans, also they could be used for mass armies, thus creating a political problem. We also have a chance of living on mars (Surprisingly NASA has plans for this), but doing so would make a new species of human, we wouldn't want interplanetary conflicts would we? Colonies all over the galaxy? Stick to the facts, and stop fantasizing about space. Crossbreeding with other life forms is utterly stupid. It'll create genetic errors, and a truckload of problem regarding this.