Do you think aliens have visited earth?

Have we ever been visited by extraterrestrials?

I'm not debating on whether or not life is out there or not. I just think there is no possible way they could have ever made it to Earth unless they were beings of pure energy. Then by our defination they wouldn't be considered living. So what if there was water? That doesn't mean that there was life there. I'm sorry to poke a hole in your theory, but none of those things are proven. I'll humor and say that at one point there was life on Venus. What are the chances that it would be intelligent or that if they were intelligent they would be anything like humans? How can we learn any lessons if there is no past to look back to?

While I don't know if extrarrestrial intelligent life exists, I do not believe we've ever been visited by it. But I do like reading theories about it.

Maybe the most fascinating stuff comes from a guy named Graham Hancock. He's got a theory that civilization was 'given' to humanity by extraterrestrials. There are quite a few holes and flaws in his results of course, but he does make one interesting point. Almost every ancient culture has a story about how civilization came to humans, and it usually takes the same form of gods or supernatural beings handing it down in various ways. Even the Jews have the Torah, which states that the law was given to Moses by God. Similar legends exist in Egyptian, Indian, Mesopotamian, Celtic, and Mesoamerican cultures.

Even ancient myths have some historical value because they often make references to real events and people. He takes it a step further by saying that the 'gods' in these ancient tales were aliens, and they've been back a few times since then, something recorded in additional writings and also portrayed in paintings and designs.

I don't agree, but it's cool to read about for some reason. I believe that the pyramids and Stonehenge, etc. were built by humans, but that they had a different kind of technology available to them that we don't know about today. They also had quite a bit of slave labor, which we don't have...

I hear Australia is full of them. . .

One of my closest friends is an alien.

No, but I think that there is life -intelligent life- in other planets. The Universe is so huge that it is inconceivable that NO other civilizations exist.

This is an estimate of how many intelligent civilizations there are in the universe. 150. And at about 2,000 light years apart scientist think the vast distant makes contact unlikley.
Space travel would take immence amounts of fuel, our neartest star to the sun would take us thousands of years to get to, and the nearest galexy is 2 million light years away.
But in my viewpoint... What if the aliens visit us live longer? And are willing to take that time for space travel and exploration. If they are able to, they are far more advanced and intelligent then us, so they are probably able to make high-speed space craft.
The fastes way to point A from B if you make points on a paper is a straite line right? Wrong. If you fold the paper so the points meet it's much closer.
I think we have been visited by extraterrestrials, far more advanced then us ever since ancient times, and even helped ancient civilizations. Not just one race of aliens but maybe many.
Their motives? They could just be scouping us out making sure everyting's Ok. I don't think they mean any harm maybe they are just curious. Or they could be running out of resourses on their planet and looking to take over ours, but they would have done this by now. I've heard about abductions. I've heard theories that they are conducting some hybred expirement.

I wish they would. We could use a fresh perspective.

I would say it's plausible, however unlikely; The distances involved are far to great, which isn't to say that there isn't life on other planets.

Nevada area 51 or whatever

It's possible. I don't think we're the only living planet in the universe. It's so vast, that there must be other life out there. Have they ever visited Earth? I think not, because if they had, it would be a one way ticket. They would never get back to their own civilization. It would take decades to get here, and decades to get back, and for what, a day trip around the Earth. Even with all the Hollywood technology, they wouldn't get back home. But it makes great topic of conversations...

'This is an estimate of how many intelligent civilizations there are in the universe. 150.'

Really? Where did you get this estimate from? There's a formula called the Drake Equation (http://en.wikipedia.org/wiki/Drake_Equation), which purports to predict the number of independent civilisations we can expect to encounter in our galaxy. The uncertainty of the terms is so high, however, that the estimates are practically useless.

'And at about 2,000 light years apart scientist think the vast distant makes contact unlikley.'

2000 light years? That would mean that even if all 150 were arranged in a neat line, the universe could be no more than about 300,000 light years across. However, the universe is estimated at more like 93 billion light years. Your figure makes more sense for our galaxy, which is about 100,000 light years across.

'Space travel would take immence amounts of fuel, our neartest star to the sun would take us thousands of years to get to'

Actually, the nearest star system is Alpha Centauri, which is only 4 light years away, a distance that could take as little as 4 years to travel, in theory (though likely much more in practice).

'I think we have been visited by extraterrestrials, far more advanced then us ever since ancient times, and even helped ancient civilizations. Not just one race of aliens but maybe many. '

Why do you think this?

'This is an estimate of how many intelligent civilizations there are in the universe. 150.'

These are the values based upon the most recent astronomical data:

Parameter Optimistic Pessimistic

---

R* 10 3
fs 0.02 0.01
fp 0.75 0.1
any 0.01 0.00001
fl 1.0 0.00001
fi 0.0001 0.000001
fc 1.0 0.1
L 1,000,000,000 100,000,000

---

Total
150. 0

If you don't understand look it up.

'And at about 2,000 light years apart scientist think the vast distant makes contact unlikley.'

I don't think you understand a light year is the amount of time it takes LIGHT to travel in a year.
To actually think it would take 4 years for out latest tecnology is ridiculous. The distance from Earth to Pluto(the last planet in the solar system) is not constant, but averages to 3.57 billion miles. The Space Shuttle orbits at 17,500 miles per hour. Therefore for us, 23 years 105 days. I suggest you do more research.

Decent rough draft sorry you don't comprehend.

LOL. I've read enough of arachnid's posts to know that if he doesn't comprehend what you're saying, it's because either it isn't scientifically valid, or you do a very poor job of explaining the science

In your case, I think it's the latter.

Is this the website where you copied and pasted this data without bothering to explain it?
http://www.godandscience.org/apologetics/ufo.html

See the section called 'How many alien civilizations in our galaxy'

SETI also has some interesting calculations, where they give optimistic and pessimistic estimates for how many solar systems could support the development of intelligent life. It's interesting to think about and worth making a part of our space exploration, although there are other priorities.

beautifulmaskerade: That's the drake equation. If you don't mention where you got the figures, though, the number 150 really doesn't mean anything, especially since the error margin for that figure is _huge_.

I'm quite aware of what light years are, and how far away pluto is, thank you. Assuming that we would travel to Alpha Centauri using the space shuttle, at orbital speeds, however, is ridiculous.

1) The space shuttle's orbital speed depends entirely on what altitude it is currently at.
2) If the space shuttle were travelling between planets or between stars, it would naturally accelerate to much higher speeds.
3) The space shuttle is completely unsuited to any sort of interstellar journey. I was assuming that any vehicle used to travel to another star system would be custom-built for the purpose, and travel at relativistic velocities - a respectable fraction of C, at least. 4 light years is a lower bound - the least time you could possibly get there in*.

* Yes yes, barring the (unlikely, alas) development of FTL travel.

Of course they have. They have been living on earth since time began, they are studying the way we live, to them we are the aliens.

Honestly there are many opinions but truly I think that they weren't aliens but another planet of humans that dumped us here and help us evolve at random times.

It actually wouldn't have to take up that much fuel. We are designing engines that gather hydrogen molecules in space and strip them of their atoms for energy. as it moves faster it collects more atoms allowing it to go even faster.

I think there is alien, just that it has never been here.

I don't think FTL travel is possible.

>>>I hear Australia is full of them. . .

Yeah tourists

If you watch the history channel at 3 or 4 in the morning, I thnk they have a show that shows you pictures of a unknown Aircraft in the sky, and some people tell their experience with the encounter of a spacecraft!

I think they are looking to buy some homes around Stevenville, Texas

Yes, I think aleins have visited Earth before. Earth is 4.54 billion years old. To say that extrateressial life has never visited Earth would be narrow-minded. The existence of life on Earth actually originated from asteroids that bombarded the Earth billions of years ago. The orgin of life on Earth probably originated from Mars. Bacteria on a piece of Mars probably blasted its way to Earth, which gave rise to life on Earth. In theory that would make every living thing on Earth, Martian in orgin. It has been proved by science that Mars once had liquid water and was much warmer during a time when the Earth was inhospitable. People from Mars had probably visited Earth billions of years ago and considered it a dead planet. Mars and Venus were probably planets that had civilizations similar to a Kardashev 3 civilization. These are civilizations that can travel anywhere in the galaxy at 1000's of times the speed of light and can harness all of the energy in the galaxy by building Dyson spheres out of photovoltaic cells which enclose the entire galaxy. This Dyson sphere and Mars and Venus were probably destroyed in some intergalactic War billions of years ago and bacteria from Mars or Venus was blasted off onto Earth during the time in Earth's violent history when asteroids and meteors would hit it all the time. How else would life just happen to rise on a hospitable planet and how could life just vanish on Mars and Venus? Global Warming? Nuclear War?