If just .001% of 10 billion Earth-like planets orbiting sun-like stars in the Milky Way have harbored advanced, intelligent life, shouldn’t we have seen some kind of evidence of their past existence, since this would equal 100,000 civilizations?

Great question! Complicated answer. Let’s start by looking Earthward at ourselves, then we’ll compare that looking spaceward toward the stars.

As you know, homosapiens are the advanced, intelligent life form on Earth which is now technologically advanced and space faring.

Now by some estimates, humans have been on this planet only for the last 200,000 years, or one fifth of one million years. There are a thousand million years in a billion years, and the Earth is about 4.54 billion years old. So, humans have been on Earth for only a tiny fraction of Earth’s existence. Here’s a graphic to illustrate that point and more to follow below.

This image illustrates what it would look like on a 24 hour clock comparing the age of Earth to the presence of humans. In fact, life itself has existed on Earth for less of half the lifespan of the planet, what to speak of humans.

So you can see, even though we have a planet in the goldilocks orbital region around our sun, someone looking at Earth many light years away would not see humans even though humans are here, because the light or radio waves haven’t reached them. They would assume this a dead planet. Humans have existed on this planet, in terms of a 24 hour clock, 1 minute and 17 seconds. In terms of exploring space, for less than 1 second.

You see, just because humans have been on Earth about 200,000 years doesn’t mean humans have been emitting radio waves and exploring space for all that time. In fact, we only began exploring space 60 years ago and emitting radio waves for a couple of hundred years. In the history of Earth, we have explored space (in terms of a 24 hour clock) for only a flash of a portion of a second.

That’s us. Now let’s look at the stars.

Let’s say there are 100,000 planets with advanced life like humans on them right now.

However, since the galaxy is 200,000 light years across, someone on a planet on the other side of the galaxy from us would not be visible to us. We’d see that as a planet with no human-like people because it would take light and radio waves 200,000 years to reach us. Now take into consideration that of the 100,000 planets with human-like people on them (as you suggest in your question), it took us 200,000 years to get to the point of emitting radio waves and exploring space. Hence, we’re looking for a very narrow window in a planet’s lifespan that intelligent life might be detected. Not only a tiny fraction of the planet’s existence has it had intelligent life, but only a tiny fraction of the time the intelligent life existed there were they able to emit radio waves and explore space, even if all conditions were favorable for that planet to eventually develop intelligent life.

Furthermore, the sky is very big. Looking for exoplanets, we have explored less than 3% of the total sky so far.

Put all of that together and the chance we would have detected other intelligent life is almost nil to date, even though it might still be out there somewhere. The guy below might be the exception.

Why might there be no life in other planets that are located in the Goldilocks Zone?

If you ascribe to various religions, then because God created life on Earth, not elsewhere.

Aside from the religious connotation, we haven’t found evidence of even a fossilized microbe from another planet to date. In fact, there is no proof life exists anywhere else other than Earth.

Now for those of us who prefer science, it’s likely life does exist somewhere else. We just can’t prove it yet. If we could prove it, then it would challenge the theory of creationism.

What are the chances of two planets from the same solar system having sentient species that reach space exploration around the same time?

This is a great question, but unfortunately no one will be able to give a definitive answer as to the chances.

This is simply because we do not yet know if life exists anywhere other than Earth. It is still within the realm of possibility that Earth is the only place where any kind of life, what to speak sentient life, exists.

Finding such life would be an affront to many religions that contend that God created life on Earth only, and therefore finding even a fossil of a microbe on another celestial body would be the holy grail of science and have reverberating effects throughout human society. The theory of evolution would be proven.

It is believed to be highly likely that life does exist elsewhere in the universe simply by the laws of probability, but that being said, we have found no evidence to support this theory.

So now we can come back to your original question: “What are the chances of two planets from the same solar system having sentient species that reach space exploration around the same time?” Based on the fact that life has not been discovered anywhere, the chances to sentient life forms existing in the same solar system is practically nil (but not impossible).

Are octopuses originally from another planet?

Are octopuses originally from another planet? It sure seems so, doesn’t it? They are a very weird creature!
But just because they are weird doesn’t mean they’re from another planet! In reality they are related to several other Earth critters. They are a mullusc and belong to the class cephalopoda along with squids cuttlefish and nautiloids. So although they are very weird, they are definitely not from another planet.
However, in the sense that we are all made of stardust that came from some Supernova explosion somewhere in the universe, then we are all from another planet or star!

Red Planet Mars 1952

I found this movie on YouTube. It’s in black and white. I thought it would be another B rated movie about green men from Mars. It was not.
A scientist played by Peter Graves, AKA original Mission Impossible guy, establishes communication with an advanced race of beings on Mars. Communication is done with radio signals.
It turns out Jesus lives on Mars and traveled to Earth to give his Sermon on the Mount. The messages from Mars reestablished the existence of God and causes the Soviet Union to collapse and the entire world to become Christians.
We never knew Mars was so important!
The movie, in the end, came across like a Sci-Fi version of Ben-Hur.

Do you think aliens have received our communications and chose not to respond?

Do you think aliens have received our communications and chose not to respond? Well, who knows, but…. radio waves travel at the speed of light. We’ve been emitting radio waves for maybe a hundred years. A hundred light years radius around our solar system doesn’t encompass a lot of stars. So the answer to your question is “probably not.”

Does life have to have a climate like Earth? Out in space somewhere, can life not exist on a frozen planet or on a sun and just evolve to be able to live in its environment?

Life exists on Planet Earth in all kinds of places that are not where you would expect life should exist. Therefore, life could exist on other planets with similar bizarre climates.

For example:

  1. Deep under the ocean there are volcanoes erupting. The water temperature is way above boiling there and yet we have found these areas teaming with life.
  2. Life has been found in bubbling hot tar.
  3. The Deinococcus is listed as the “world’s toughest bacterium” in the Guinness Book of World Records because it withstands huge amounts of radiation that no life should be able to withstand.
  4. Pitch Lake in Trinidad is 250 deep and bubbling with hydrocarbon fumes seeping from oil reserves and is full of microscopic life.
  5. Lake Untersee in Antarctica has been iced over for 100,000 years. It is here they find Stromatolites mounds built by microorganisms.
  6. Researchers found these autochthonous organisms at the bottom of a South African gold mine.

Credit. So if life can exist in all these unexpected places on Earth (and more) then there is some possibility life can exist in different environments on other planets. The problem? We just haven’t found anything yet.

Does anyone believe in extraterrestrial life? If yes, why? If no, why not?

Pretty much all of science and scientists in the world believe in extraterrestrial life, even though no evidence of extraterrestrial life has ever been found to date. Why do scientists believe in extraterrestrial life? Simply because there are billions of stars in the Milky Way galaxy and billions of galaxies in the universe. Somewhere it is highly likely that extraterrestrial life exists. It is even possible that extraterrestrial life of some form or another exists on Titan, within our own solar system!

Will an alien invasion by secular and militaristic extraterrestrials solve a lot of problems on Earth?

An alien invasion by secular and militaristic extraterrestrials would solve one of the biggest problems we have here on Earth. That problem being: does life exist on other planets? Finally we would have an answer!

Shouldn't we be looking for life on planets that formed over 10 billion years ago as they've had more time for life to form?

Planets that formed over 10 billion years ago are about 5 billion light years from us, meaning that if we could somehow study planets that far away (we can’t) the light reaching us from there would have taken 5 billion years to reach us. Therefore, we’d be seeing what the planet looked like 5 billion years ago, not what it looks like now. Below is what we are able to see of the most distant galaxy that we have seen to date. It’s about 13 billion light years and we are just seeing the early stages of development because it took light 13 billion years to reach us.

As you can see from the image, Hubble can barely make out the galaxy, what to speak of any planets that might be orbiting the billions of stars inside that galaxy. The best we can do is study planets in our vicinity of the Milky Way.