life on other planets...

A poll:
Do you think (yes or no) that the Earth has been visited in the past by extraterrestrial voyagers?
Do explain your choice of answer if you want.

No, I don't think so.
If so we should have some observational evidence for that.

Originally posted by eatmybishop
if we had proof that that life existed on other planets, do you think the governments will keep it secret?

That depends on if there's some reason to keep it secret.

Originally posted by FabianFnas
No, I don't think so.
If so we should have some observational evidence for that.

What kind of evidence would you expect to see? Maybe the biggest evidence is US. That is to say, maybe they seeded our planet with their life forms that developed into us.
But for evidence for a visit? Why would there be anything from that?
Suppose they visited 10,000 years ago and left their equivalent of beer cans or cigarette butts. I would think anything material would have disintegrated long ago.

Originally posted by sonhouse
What kind of evidence would you expect to see? Maybe the biggest evidence is US. That is to say, maybe they seeded our planet with their life forms that developed into us.
But for evidence for a visit? Why would there be anything from that?
Suppose they visited 10,000 years ago and left their equivalent of beer cans or cigarette butts. I would think anything material would have disintegrated long ago.

I'm not particulary into Velikovsky's ideas, but something of that kind though. Some junk from their spacecrafts or something...

Originally posted by sonhouse
It seems likely we will not be using radio waves some time into the future because of better means whatever they turn out to be. I suspect though, whatever means it turns out to be, can be detected by the right sensors at LY distances. Here at my company we are advancing the art of getting more and more information down a optical fiber. I now test a laser m ...[text shortened]... able to discriminate between large natural energy sources and large designed energy sources.

Has your company or anyone else figured how to send a signal of any kind faster than the speed of light?

How much energy would it take to send even one atom or any particle faster than the speed of light?

Has anyone read Poul Anderson's 1970s essay "Our Many Roads to the Stars?"

Incidentally, Carl Sagan believed while there is mathematically almost a certainty that ET life of some sort exists, if not nearby, none of the ETs have ever been or will likely ever come here because the cab fare is just too damn much.

I've yet to see anyone string me along and prove otherwise, so to speak.

And the time-lag btw transmissions of any kind at light speed or less would make for some very futile conversations, Sagan wrote.

But this, like politics, is a subject on which almost everyone has a belief system they prefer over calculation, experience, logic or proof.

Kind of like the situation in the USA where the majority of people would demand evidence, if told that a bite of a certain kind of mushroom would make your feet and other things grow much larger, but do not question the literal interpretation of a book written thousands of years ago which happens to be in the drawer next to their bed in every hotel room.

I prefer to go figure -- but, hey, whatever ....

Originally posted by Scriabin
Has your company or anyone else figured how to send a signal of any kind faster than the speed of light?

How much energy would it take to send even one atom or any particle faster than the speed of light?

There is no way to send information faster than the speed of light.
There is no way to send even the smallest atom or any other known particle faster than the speed of light.
However, if the particle is massless, then it is possible to send it *in* the speed of light. (A photon for instance.)

Originally posted by FabianFnas
There is no way to send information faster than the speed of light.
There is no way to send even the smallest atom or any other known particle faster than the speed of light.
However, if the particle is massless, then it is possible to send it *in* the speed of light. (A photon for instance.)

Hence the cab fare.

Too high.

Probability of ETs ever being here or ever coming here = the negative value of distance x velocity

In other words, it isn't worth the time, the cost, etc.

that is, until someone can show and prove there is a way to find a short cut.

So far, no one has.

Originally posted by Scriabin
Hence the cab fare.

Too high.

Probability of ETs ever being here or ever coming here = the negative value of distance x velocity

In other words, it isn't worth the time, the cost, etc.

that is, until someone can show and prove there is a way to find a short cut.

So far, no one has.

In the Thread 91018 page 8, I posed some questions

Do you think...

(1) It is not possible to go by the speed of light.
(2) It is possible to go by the speed of light.
(3) It is possible to go faster than light.

(4) It will never be possible to go faster than light, ever.
(5) It is not possible to go faster than light with present knowledge, but in the future with new technology it is possible when we know how.

(6) In the future we will have technology to go anywhere in the universe without going faster than light (for example with the aid of using paralell dimensions, folding space, or other methods).

Read the answers and/or give your own answer.

I say that it is really impossible to go faster than light, but we don't know if there is a way to get to the destination before the light does.
This doesn't mean that you faster than light, but you've found an extradimensional shortcut. Not possible with today's technology, but perhaps the future's or alien technology.

But who knows...

Originally posted by FabianFnas
In the Thread 91018 page 8, I posed some questions
[quote]Do you think...

(1) It is not possible to go by the speed of light.
(2) It is possible to go by the speed of light.
(3) It is possible to go faster than light.

(4) It will never be possible to go faster than light, ever.
(5) It is not possible to go faster than light wi ...[text shortened]... with today's technology, but perhaps the future's or alien technology.

But who knows...

1. According to Special Relativity the total energy of an object increases as its speed increases and approaches infinity as the object's speed approaches the speed of light. This means that it would take an infinite amount of energy to accelerate an object to the speed of light. This disposes of just about all your questions, except the fact that we don't know what we don't know.

2. see this NASA website for a lot of good questions and answers to the basic questions about relativity, curved space time, velocity, acceleration, time dilation, and so on:

http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html

for example: Why is the velocity of light the max speed despite its dependence on the permeability and dielectric constants?

The Answer
The speed of light in a given medium does indeed depend on the permeability and dielectric constants. As you likely know together these form the index of refraction n = (epsilon * mu).5 In turn the index of refraction determines the velocity by v = c/n. The values of mu and epsilon for all known materials is greater than the value in a vacuum, so the speed of light has a maximum value in a vacuum. The precise reason why the values for mu and epsilon are smaller in media rather than a vacuum is a little outside of astrophysics and is more under the domain of materials science or solid state physics.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970611d.html
the speed of light in vacuum has always been observed to be constant (c) --- this is not Einstein's invention, but rather the fact on which he based his theories of relativity.

On the other hand, physicists have always known that the speeds of light in gas, liquid, and solids (air, water, glass etc.) depend on the material composition. This is the domain of optics; the consensus of those who know these recent experiments think that they are exciting new developments in optics, which however does not contradict relativity. I.e., faster than light travel still firmly belongs in science fiction, unfortunately.

If you have a Java-enabled browser, check out:

http://www.netspace.net.au/~gregegan/APPLETS/20/20.html

Another answer from a NASA volunteer astrophysics guru:

The laws of science do not distinguish between the forward and backward directions of time -- yet they do distinguish the past from the future (time increases as disorder increases). There are some solutions to the equations of General Relativity which would allow for travel back and forth in time....(1) would require that you move faster than the speed of light, but we know that this cannot be done; (2) would require space-time to be very warped and a sort of "tunnel" between two space-time points to be present (called a "wormhole".) Such tunnels would not last long enough on their own for anyone to travel through them (unless the traveler discovered some way or built some machine which would keep the tunnel open). There are all sorts of other conditions which would have to be imposed on space-time in order for human beings to travel into the past. All of these conditions tend to conspire against time travel being more than a theoretical possibility. But, as of 1997, our understanding of physics causes the possibility of time travel to remain an open question. NOTE: What I have said here is related to big objects like humans...and my comments do not necessarily apply to very small (subatomic) objects.

Another answer I found useful that bears on your questions:
How can one prove the existence of tachyons and once it is proven, can they be implemented for space travel like in Star Trek (i.e. faster than light space travel)?

The Answer
Probably two of my favorite popular level treatments of the possible technological implications of tachyons are:

"Future Magic: How Today's Science Fiction Will Become Tomorrow's Reality" by Dr. Robert L. Forward, Avon Book, 1988.

and

"Faster Than Light: Superluminal Loopholes in Physics" by Dr. Nick Herbert, Plume Books, 1988.

Personally, I think Bob Forward's is the better of the two.

As to proving the existence of tachyons, one basically has to discover a particle interaction which can *only* be explained by the presence of one or more tachyons. Some theoreticians argue that if tachyons exist, the universe could be filled with them but they interact so weakly with ordinary matter that we can't detect them. Physicists have searched through some experimental records and so far none of the high-energy accelerator labs have detected an interaction which can *only* be explained by tachyons. This means that tachyons must be far more weakly interacting than neutrinos. If they do exist, tachyons would be extremely difficult to utilize under our current understanding of physics.

You could travel faster than light if you could turn yourself (and your starship) into a tachyon. However, special relativity indicates that if you did this, you could travel back in time and violate causality - the idea that causes must precede their effects. You could wind up in the "Grandfather Paradox": What if you go back in time and kill your grandfather before your father is born? But if you're never born, how could you go back and kill your grandfather?

There seems to be a lot of bogus science on the Web surrounding the subject of tachyons. A number of companies seem to like the name in their product so be careful what you read.
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970612b.html

But one should also remember we don't know what we don't know -- so it would be wise to keep an open mind about what we might know some day:

from another NASA volunteer: Worm holes can be time machines as well as space machines. Thus you can go through a series of wormholes and end up wherever and whenever the wormholes are set up to take you (within limits).

Carl Sagan, when writing Contact, asked Kip Thorne (one of the world's leading relativists) how to transport a person to distant stars, have her come back to find that no time had passed on Earth (which is in both the book and the movie).

From this question, Kip Thorne revitalized the whole modern field of the study of wormholes, a field which had lain dormant for a few decades until Thorne figured out how to make a wormhole people could actually travel through.

A good book on wormholes is:
Black holes and Timewarps, Einstein's Outrageous Legacy, Kip Thorne, ISBN 0393312763

Originally posted by Scriabin
1. According to Special Relativity the total energy of an object increases as its speed increases and approaches infinity as the object's speed approaches the speed of light. This means that it would take an infinite amount of energy to accelerate an object to the speed of light. This disposes of just about all your questions, except the fact that we don't ...[text shortened]... Java-enabled browser, check out:

http://www.netspace.net.au/~gregegan/APPLETS/20/20.html

Assuming we survive the next thousand years as a civilization, things may be seen to be different then if science progresses as it has in the last thousand years. Of course as we speak, any of the sci fi solutions are just that till further notice. It makes sense to me the idea that our universe popped out of another which started out as a black hole there ending up in a white hole here which would be the big bang as we perceive it. So the thinking goes, what constants we have in our universe is similar but not exactly the same as the universe which spawned ours, so in the parent universe the speed of light may be ten times greater than here, just depends on the underlying physics of that universe, and that that universe itself was the white hole side of another even bigger universe which spawned that one, etc., with even more departures from the constants we know in this one. Maybe one day science will win out and we will figure out how to go from one universe to another. Don't hold your breath though🙂

So, despite what I said about the cab fare, I would not say it is really certain at all that it is impossible ever to find a way to get from one part of the universe to another faster than light would -- just highly unlikely given what we know now.

For some advanced and fun ways to explore ideas under discussion in this vein, see The Advanced Warp Physics site at

http://da_theoretical1.tripod.com/wdphysics.html

A quote I really like to keep in mind on this subject is this:

"There have been many people (some of them quite well known), that have `proved' by `calculation' that interstellar flight is `impossible.' Actually, in each case, all they `proved' was that with the initial `obvious' assumptions that they forced on the problem, that the problem was made so difficult that they were unwilling to consider it further. "

-Dr. Robert L. Forward, 1986