Size a solution to Fermi Paradox?

[Phi for All]

17 minutes ago, FreeWill said:

Everywhere.

Yet we do not know the math and physics required to understand what and where they communicate. 

Sorry, but that's not a great answer. It's a cop-out. You're basically demanding that aliens exist and are here, ignoring that there's no evidence that strong to support such a assertion, and then claiming that operating on some kind of unfamiliar "frequency" we don't understand makes them invisible. 

Communication is all about patterns, and we're pattern-finding machines with some of the best communication skills on the planet. While there are maths and physics concepts we don't fully understand, it's doubtful that lack of knowledge would stop us from recognizing patterns aimed at communicating information. We might not know what an alien communication says exactly, but do you really think we would fail to recognize an attempt to communicate?

7 minutes ago, Moontanman said:

Self driving cars are already a thing, why not self flying cars? 

I was actually thinking of that as a reason why NOT to have flying cars. If you remove traffic congestion through automation, why do you need to fly? And if you need to fly, why do you need a car?

I suppose if self-driving cars made auto insurance unnecessary, the same might apply to self-flying cars, but I don't think you'll ever remove the issue of liability. Still, I don't think flying cars are going to be anything but a billionaire's diversion. I don't want to be in the skies with some of the people I've driven on the ground with.

[Moontanman]

15 minutes ago, swansont said:

I guess you must be in the "there are no aliens" camp, too, seeing as there are no actual barriers to interstellar space travel, and your answer to the OP sounds like it's "no, space is not too big".

If not, where are they?

They avoid gravity wells... Actually you have to assert that aliens want to come here before you can say anything. Time is also a factor, do alien civilizations last forever? Ours has lasted a few thousand years so far, time is as big a factor if not larger than space. There could have been a million civilizations in the Milky Way so far and they could be separated by not just thousands of light years but thousands of years as well. I am of the "opinion" that planets would be avoided due to the fact that life has adapted to the earth, finding an earth like planet is no guarantee that we could live there. In fact slight variations in chemicals could make a planet uninhabitable to us even though the life that has adapted to it is prolific. It makes much more sense to build your own worlds than to try and find a world that happens to be perfect for you. 

Some alien specialist might be interested in us for various reasons but landing on the white house lawn would destroy the study. There is no reason to think that aliens would want to contact us and the idea that we could simply see them through their radio "leakage" is false. It's doubtful that we could detect a civilization identical to us at Alpha Centauri unless they were specifically pointing a high powered transmitter directly at us. Our radio leakage fizzles out within a light year or so due to the interstellar medium. 

Military type radar would be an exception but it would unlikely be a repeating signal and we have detected such signals from various places in our galaxy but they are not given weight because they do not repeat. 

I think we don't see aliens because that is exactly what we would expect to see unless they are intentionally signaling us and we do not do that, why should they? 

[swansont]

1 hour ago, FreeWill said:

Everywhere.

Yet we do not know the math and physics required to understand what and where they communicate. 

A condition of the question was that no new physics is required.

[FreeWill]

1 hour ago, Phi for All said:

You're basically demanding that aliens exist and are here, 

They are not demanded to be here. Why would they be here? I think there is communication between Advanced Intelligences throughout the Universe. But why they should be anywhere else than their max cloose neighborhood. If teleportation of information would be possible there is one more reason not to move further than it is necesseary. What can and advanced, intelligent race do with more space or matter when they own more than they could ever use.

I demand that they exist since the Universe is far too big with trillions of galaxies with billions of starts in them, and most Star with a habitable zone around them.

I know how life finds its way in the most extreme envirnoments, so I can not exclude that life and with so many habitable zones around the stars of the Universe, intelligent life, older and more adnvanced than ours, did not evolve. 

 

Edited July 18, 2019 by FreeWill

[Strange]

6 minutes ago, FreeWill said:

I think there is communication between Advanced Intelligences throughout the Universe.

Do you have any evidence for that.

[swansont]

1 hour ago, Moontanman said:

They avoid gravity wells... Actually you have to assert that aliens want to come here before you can say anything. Time is also a factor, do alien civilizations last forever? Ours has lasted a few thousand years so far, time is as big a factor if not larger than space. There could have been a million civilizations in the Milky Way so far and they could be separated by not just thousands of light years but thousands of years as well.

I don’t believe the math work out for that. 50k LY in radius and 1000 LY thick is a volume of less than 10^13 cubic LY. A million civilizations means they require a volume of less than 10^7 cLY, or a radius of ~200 LY (assuming equal spacing for max separation)

So a million civilizations could not all be thousands of LY apart. For any one that is that isolated, many others have to be much closer.

They don’t have to come here, we just need to be able to detect them.

1 hour ago, Moontanman said:

I am of the "opinion" that planets would be avoided due to the fact that life has adapted to the earth, finding an earth like planet is no guarantee that we could live there. In fact slight variations in chemicals could make a planet uninhabitable to us even though the life that has adapted to it is prolific. It makes much more sense to build your own worlds than to try and find a world that happens to be perfect for you. 

So these are impediments for them colonizing but somehow not for us?

And now world building is in the inevitable march of technology?

1 hour ago, Moontanman said:

Some alien specialist might be interested in us for various reasons but landing on the white house lawn would destroy the study. There is no reason to think that aliens would want to contact us and the idea that we could simply see them through their radio "leakage" is false. It's doubtful that we could detect a civilization identical to us at Alpha Centauri unless they were specifically pointing a high powered transmitter directly at us. Our radio leakage fizzles out within a light year or so due to the interstellar medium. 

Citation needed.

We seem to be able to do radio astronomy. The interstellar medium doesn’t filter those signal, often over much, much greater distances (and attenuation is an exponential)

1 hour ago, Moontanman said:

Military type radar would be an exception but it would unlikely be a repeating signal and we have detected such signals from various places in our galaxy but they are not given weight because they do not repeat. 

What makes military radar immune to “fizzling out”?

1 hour ago, Moontanman said:

I think we don't see aliens because that is exactly what we would expect to see unless they are intentionally signaling us and we do not do that, why should they? 

We don’t?

https://en.m.wikipedia.org/wiki/Arecibo_message

2 hours ago, Moontanman said:

Self driving cars are already a thing, why not self flying cars? 

Not really. They are not reliably autonomous.

[FreeWill]

Quote

Do you have any evidence for that.

Yes, we humans communicating throughout longer distances of spacetime (which is part of the Universe). 

Note: advancement is relative 

Edited July 18, 2019 by FreeWill

[Strange]

2 minutes ago, FreeWill said:

Yes, we humans communicating throughout longer distances of spacetime (which is part of the Universe). 

Note: advancement is relative 

Is that supposed to be an answer to my request for evidence?

The fact that humans can communicate across distances is not evidence that there are other intelligences in the universe, nor that they are communication with each other.

[FreeWill]

3 minutes ago, Strange said:

Is that supposed to be an answer to my request for evidence?

The fact that humans can communicate across distances is not evidence that there are other intelligences in the universe, nor that they are communication with each other.

True. It shows the possibility and the need for communication. 

Obviously No. But I can suspect as I can suspect that other intelligent lifes are out there

Edited July 18, 2019 by FreeWill

[Strange]

Just now, FreeWill said:

True. 

Obviously No. But I can suspect as I can suspect that other intelligent lifes are out there

OK. But this is a science forum, so guesses and making stuff up don't really count for much.

[Moontanman]

8 hours ago, swansont said:

I don’t believe the math work out for that. 50k LY in radius and 1000 LY thick is a volume of less than 10^13 cubic LY. A million civilizations means they require a volume of less than 10^7 cLY, or a radius of ~200 LY (assuming equal spacing for max separation)

 

Not if they were a million years apart in time, there are, estimate, 500 billion stars in the milky way, if one in a million have an advanced civilization then 500,000 of them exist but divide that by the age of the galaxy, I'm not sure what that is but let's just say a ballpark figure of 10 billion years. If an advanced technological civilization lasts 10,000 years then they could be a million years apart from each other in time. 

 

8 hours ago, swansont said:

So a million civilizations could not all be thousands of LY apart. For any one that is that isolated, many others have to be much closer.

They don’t have to come here, we just need to be able to detect them.

So these are impediments for them colonizing but somehow not for us?

And now world building is in the inevitable march of technology?

Citation needed.

We seem to be able to do radio astronomy. The interstellar medium doesn’t filter those signal, often over much, much greater distances (and attenuation is an exponential)

https://en.wikipedia.org/wiki/Fermi_paradox

Quote

Regarding the first point, in a 2006 Sky & Telescope article, Seth Shostak wrote, "Moreover, radio leakage from a planet is only likely to get weaker as a civilization advances and its communications technology gets better. Earth itself is increasingly switching from broadcasts to leakage-free cables and fiber optics, and from primitive but obvious carrier-wave broadcasts to subtler, hard-to-recognize spread-spectrum transmissions."^[111]

Quote

Radio technology and the ability to construct a radio telescope are presumed to be a natural advance for technological species,^[52] theoretically creating effects that might be detected over interstellar distances. The careful searching for non-natural radio emissions from space may lead to the detection of alien civilizations. Sensitive alien observers of the Solar System, for example, would note unusually intense radio waves for a G2 star due to Earth's television and telecommunication broadcasts. In the absence of an apparent natural cause, alien observers might infer the existence of a terrestrial civilization. It should be noted however that the most sensitive radio telescopes currently available on Earth would not be able to detect non-directional radio signals even at a fraction of a light-year, so it is questionable whether any such signals could be detected by an extraterrestrial civilization. Such signals could be either "accidental" by-products of a civilization, or deliberate attempts to communicate, such as the Arecibo message. A number of astronomers and observatories have attempted and are attempting to detect such evidence, mostly through the SETI organization. Several decades of SETI analysis have not revealed any unusually bright or meaningfully repetitive radio emissions.

8 hours ago, swansont said:

What makes military radar immune to “fizzling out”?

Military radar is both high powered and directional, radio leakage is not. 

 

8 hours ago, swansont said:

We don’t?

https://en.m.wikipedia.org/wiki/Arecibo_message

One short message directed at the magellanic clouds is hardly a concentrated effort to draw attention to ourselves... 

8 hours ago, swansont said:

Not really. They are not reliably autonomous.

There are Military drones that can take off and land autonomously and autonomous cars already exist as well as tractor trailers.   

[swansont]

4 hours ago, Moontanman said:

Not if they were a million years apart in time, there are, estimate, 500 billion stars in the milky way, if one in a million have an advanced civilization then 500,000 of them exist but divide that by the age of the galaxy, I'm not sure what that is but let's just say a ballpark figure of 10 billion years. If an advanced technological civilization lasts 10,000 years then they could be a million years apart from each other in time. 

There's no way that advanced life could have existed for the first several billion years of the universe, and arguably could not have happened for a few billion beyond that.

4 hours ago, Moontanman said:

https://en.wikipedia.org/wiki/Fermi_paradox

That says nothing about the attenuation by the interstellar medium.

4 hours ago, Moontanman said:

Military radar is both high powered and directional, radio leakage is not. 

Again, this would only mean that the signal carries a little further, and if a weak signal is essentially gone after a LY (your contention) then a stronger one is gone after 2 or 3. Which makes zero difference.

4 hours ago, Moontanman said:

One short message directed at the magellanic clouds is hardly a concentrated effort to draw attention to ourselves... 

You didn't say concentrated effort. You said we don't do it.

4 hours ago, Moontanman said:

There are Military drones that can take off and land autonomously and autonomous cars already exist as well as tractor trailers.   

Drones are not cars, and don't operate in the same complex environment. Are any vehicles which drive in traffic doing so in anything other than a test program (typically with a driver on hand for when it fails)? I keep reading about them hitting pedestrians. Also how you can trap them

[AUDI R6]

We are the most intelligent species untill some different is proved:)

[dimreepr]

37 minutes ago, AUDI R6 said:

We are the most intelligent species untill some different is proved:)

We don't even know if we're the most intelligent species on this planet...

How are you defining intelligence?

The ability to know things are bad/stupid, but do the opposite?

[Moontanman]

4 hours ago, swansont said:

There's no way that advanced life could have existed for the first several billion years of the universe, and arguably could not have happened for a few billion beyond that.

Please be specific, how far back could life have existed? If it's just a few thousand years then you have a point if life could have existed several billion years ago I don't think you have a leg to stand on. 

4 hours ago, swansont said:

That says nothing about the attenuation by the interstellar medium.

Ok, even though it does state .3 light years as the limit. 

This one says 16 light years for certain signals and explains why military radar is different. 
https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#77c621915de7

Quote

The radar beams are potentially detectable by current radio facilities such as the Arecibo Observatory and FAST and the planned future Square Kilometer Array at distances of tens to hundreds of thousands of lightyears. However, they are transient and only very rarely aimed at any star because they’re tracking objects moving across the sky in the foreground. So unless an astronomer on an Earth duplicate at Tau Ceti were aiming their equivalent of the Deep Space Network directly at the solar system, we would be very unlikely to pick up those radar beams.

http://curious.astro.cornell.edu/about-us/131-observational-astronomy/seti-and-extraterrestrial-life/seti/795-wouldn-t-the-vast-distances-of-space-distort-seti-signals-into-unintelligeble-forms-intermediate

Ok, I can't find a direct reference to the interstellar medium problem, I know I've seen it, in fact i have posted a link to it in other threads in the past but for some reason I am google blind at the moment. I can't seem to find the right search criteria 

4 hours ago, swansont said:

Again, this would only mean that the signal carries a little further, and if a weak signal is essentially gone after a LY (your contention) then a stronger one is gone after 2 or 3. Which makes zero difference.

https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#77c621915de7

Quote

The radar beams are potentially detectable by current radio facilities such as the Arecibo Observatory and FAST and the planned future Square Kilometer Array at distances of tens to hundreds of thousands of lightyears. However, they are transient and only very rarely aimed at any star because they’re tracking objects moving across the sky in the foreground. So unless an astronomer on an Earth duplicate at Tau Ceti were aiming their equivalent of the Deep Space Network directly at the solar system, we would be very unlikely to pick up those radar beams.

 

4 hours ago, swansont said:

You didn't say concentrated effort. You said we don't do it.

Now you are just being pedantic... 

4 hours ago, swansont said:

Drones are not cars, and don't operate in the same complex environment. Are any vehicles which drive in traffic doing so in anything other than a test program (typically with a driver on hand for when it fails)? I keep reading about them hitting pedestrians. Also how you can trap them

The tech is advancing do rapidly I am not willing to use current problem to condemn the inevitability of autonomous cars... or airplanes... 

[The Shadow]

On 7/18/2019 at 2:15 PM, Moontanman said:

Self driving cars are already a thing, why not self flying cars? 

In addition, it really does not need to be like a, Jetsons cartoon, zipping in any direction at will. Indeed, that would pose higher danger and/or technology to support it. Perhaps, like you stated, they could be self driving but I propose they follow road & interstate paths and directional flows already established. Including red lights and stop signs. This would be a more orderly and controlled transportation flow.

The advantage still remains for alleviating traffic congestion (2D) since you can stack multiple vehicles in the "z", or vertical, axis (different altitudes, I really mean). 

I hope I live long enough to witness transportation like this...should technology be able to advance it safely and effectively (cost and utilization factors).

On 7/18/2019 at 2:16 PM, Phi for All said:

, it's doubtful that lack of knowledge would stop us from recognizing patterns aimed at communicating information. 

What if an advanced civilization was trying to communicate using neutrinos? My understanding is mankind would not be able to decipher a pattern from them...at least not currently.

On 7/18/2019 at 4:32 PM, Strange said:

OK. But this is a science forum, so guesses and making stuff up don't really count for much.

In the spirit of discussing explanations and/or Pro/Con Fermi Paradox...I believe all we have are guesses and making things up. 

[swansont]

On 7/19/2019 at 11:26 AM, Moontanman said:

Please be specific, how far back could life have existed?

I am not prepared to make a specific pronouncement. I know that atoms didn't even exist until about 380,000 years after the BB, and then you'd need for stars to form (that took another few hundred million years) and then go supernova, because at that point you only have H, He and Li in the universe. So you have to add in that life cycle of stars just so you have some Carbon. You probably need a second round of star formation/supernova, too, in order to form the heavier elements that one would need as an advanced civilization — probably not going to do anything advanced without metals. I don't know how many billions of years each stage would take. 1? 2? 3?

Even after that, you need a solar system around the star that ignites. Planets have to form and cool, and any early-formed life would have to survive bombardment/collision from anything left over from planet formation, which is more frequent for a young planet. So you likely have a delay before life takes hold on the new planet

On 7/19/2019 at 11:26 AM, Moontanman said:

If it's just a few thousand years then you have a point if life could have existed several billion years ago I don't think you have a leg to stand on. 

We know life on earth is billions of years old, so I can't make sense of this.

On 7/19/2019 at 11:26 AM, Moontanman said:

Ok, even though it does state .3 light years as the limit. 

Where? It wasn't in the section on radio.

On 7/19/2019 at 11:26 AM, Moontanman said:

This one says 16 light years for certain signals and explains why military radar is different. 
https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#77c621915de7

Nothing about interstellar attenuation being the stumbling block, though, which was the claim I objected to.

 

On 7/19/2019 at 11:26 AM, Moontanman said:

Now you are just being pedantic... 

Pretty weak defense for moving the goalposts, IMO.

 

[Moontanman]

3 hours ago, swansont said:

I am not prepared to make a specific pronouncement. I know that atoms didn't even exist until about 380,000 years after the BB, and then you'd need for stars to form (that took another few hundred million years) and then go supernova, because at that point you only have H, He and Li in the universe. So you have to add in that life cycle of stars just so you have some Carbon. You probably need a second round of star formation/supernova, too, in order to form the heavier elements that one would need as an advanced civilization — probably not going to do anything advanced without metals. I don't know how many billions of years each stage would take. 1? 2? 3?

Nonetheless, time could very well separate civilizations as well as distance.  If civilizations are rare this has to be a factor in the Fermi paradox. IMHO there is no Fermi paradox, the paradox is an illusion I would assert we see what should expect to see...

https://www.forbes.com/sites/quora/2017/01/27/how-far-into-space-can-radio-telescopes-hear/#57df9f2f5de7

https://en.wikipedia.org/wiki/Fermi_paradox

Quote

Radio technology and the ability to construct a radio telescope are presumed to be a natural advance for technological species,^[52] theoretically creating effects that might be detected over interstellar distances. The careful searching for non-natural radio emissions from space may lead to the detection of alien civilizations. Sensitive alien observers of the Solar System, for example, would note unusually intense radio waves for a G2 star due to Earth's television and telecommunication broadcasts. In the absence of an apparent natural cause, alien observers might infer the existence of a terrestrial civilization. It should be noted however that the most sensitive radio telescopes currently available on Earth would not be able to detect non-directional radio signals even at a fraction of a light-year, so it is questionable whether any such signals could be detected by an extraterrestrial civilization. Such signals could be either "accidental" by-products of a civilization, or deliberate attempts to communicate, such as the Arecibo message. A number of astronomers and observatories have attempted and are attempting to detect such evidence, mostly through the SETI organization. Several decades of SETI analysis have not revealed any unusually bright or meaningfully repetitive radio emissions.

 

 

3 hours ago, swansont said:

Even after that, you need a solar system around the star that ignites. Planets have to form and cool, and any early-formed life would have to survive bombardment/collision from anything left over from planet formation, which is more frequent for a young planet. So you likely have a delay before life takes hold on the new planet

Recent research has pushed the possible existence of life on Earth back to more than 4 billion years, this would appear to indicate that life starts as soon as it's possible. 

3 hours ago, swansont said:

We know life on earth is billions of years old, so I can't make sense of this.

 

I was referring to life in the galaxy, there are so many ifs involved that this is nothing but speculation but even if life in not rare civilizations could still be separated in in not only space but in time as well. A million civilizations could be separated by thousands of light years but also hundreds of thousand years in time. At any one time there could only be a handful of civilizations active and those would likely be separated by tens of thousands of light years in space. A civilization that far away would not be aware of us and unless they were intentionally sending out a high powered omnidirectional signal for tens of thousands of years we would be unaware of them. And due to the speed of light limitations they could not be aware of us...

There is no Fermi Paradox, we see what we should expect to see when passively looking for signals of ET... 

 

3 hours ago, swansont said:

Where? It wasn't in the section on radio.

Nothing about interstellar attenuation being the stumbling block, though, which was the claim I objected to.

Ok, I'll concede that but the fact does remain that we could not detect a civilization equal to ours in the Alpha Centauri system unless they were intentionally trying to be recognised. 

3 hours ago, swansont said:

 

Pretty weak defense for moving the goalposts, IMO.

 

No, not at all, the signal you are referring to was not omni directional, it was directed at the Magellanic clouds 16,000 light years away, it wasn't repeating over time and if we received such a signal it would be discounted. To have a real attempt at letting aliens know we are here would take a very powerful omnidirectional signal that we are currently incapable of generating due to both the power requirements and lack of infrastructure. 

[swansont]

1 hour ago, Moontanman said:

 No, not at all, the signal you are referring to was not omni directional, it was directed at the Magellanic clouds 16,000 light years away, it wasn't repeating over time and if we received such a signal it would be discounted. To have a real attempt at letting aliens know we are here would take a very powerful omnidirectional signal that we are currently incapable of generating due to both the power requirements and lack of infrastructure. 

You made no modifiers to your claim.  Only after-the-fact, once the claim was rebutted.

It's moot, anyway, since the claim I was responding to was "size is not a valid argument, technology could eventually conquer the entire local cluster of galaxies given a few hundred million years." followed by the claim that the only missing piece was fusion. "The only current flaw I am aware of is our lack of controlled fusion."

The side-track into radio signals was just that — a side track, based on an unsupported implication that the interstellar medium is responsible for the decrease in signal strength. I brought that up because it ignored the (IMO) more obvious 1/r^2 decrease, and also fit in with a previous misconception that the interstellar medium is something other than a near-perfect physical vacuum, exceedingly sparsely populated with matter.

Other arguments have morphed along the way, too. Every time a shortcoming is pointed out. No agreement that the claim is flawed. Just a rewording of the claim.

 

 

 

[Moontanman]

4 hours ago, swansont said:

You made no modifiers to your claim.  Only after-the-fact, once the claim was rebutted.

It's moot, anyway, since the claim I was responding to was "size is not a valid argument, technology could eventually conquer the entire local cluster of galaxies given a few hundred million years." followed by the claim that the only missing piece was fusion. "The only current flaw I am aware of is our lack of controlled fusion."

The side-track into radio signals was just that — a side track, based on an unsupported implication that the interstellar medium is responsible for the decrease in signal strength. I brought that up because it ignored the (IMO) more obvious 1/r^2 decrease, and also fit in with a previous misconception that the interstellar medium is something other than a near-perfect physical vacuum, exceedingly sparsely populated with matter.

Other arguments have morphed along the way, too. Every time a shortcoming is pointed out. No agreement that the claim is flawed. Just a rewording of the claim.

 

 

 

I was trying to clarify the assertions I had made. 

Ok, lets see how your assertion that we are sending out signals with the intention of notifying aliens we are here VIA the message sent by Arecibo.

 https://www.iop.org/resources/topic/archive/seti/index.html

Quote

This has been attempted several times, the best known of which was transmitted by the Arecibo radio observatory in 1974. The message was a sequence of binary digits, which, when decoded shows pictorial and mathematical representations of a human being, our solar system and DNA.

It was aimed at the M13 globular cluster of around 30 000 stars 21 000 light years away, which will no longer be there by the time the message arrives – it was intended more as a demonstration of technology and to be thought-provoking.

Although the power of deliberately transmitted beams doesn’t drop as rapidly as with accidental broadcasts, they are still only likely to be strong enough to be detected within perhaps a few hundred to a few thousand lightyears. The effective range of a transmission depends on several factors, including the frequency, bandwidth and transmission power, as this range-calculator shows.

Even for messages at high power, any extraterrestrials waiting to hear from us could need a radio dish several kilometres across. They may not have the budget for it.

It is quite possible that I am confused about the interstellar medium interfering with radio signal leakage detection. I concede that point. 

[swansont]

Interesting side note to the interstellar travel issue

 

[Sensei]

8 minutes ago, swansont said:

Interesting side note to the interstellar travel issue

 

..it does not take into account possibility of mass extinction within these hundred years, or similar event, which would stop development of faster engines..

ps. Kinda similar "problem" to "why to buy computer/TV/mobile/electronic device/car today? Tomorrow/after week/month/year the same product will be cheaper and as good as today". It ends with endless loop, if there is constant progress.

[swansont]

3 hours ago, Sensei said:

..it does not take into account possibility of mass extinction within these hundred years, or similar event, which would stop development of faster engines..

It’s the answer to a specific scenario, with one variable, and multiple assumptions. It doesn’t take into account probably billions of things.

Much like solving almost any physics problem doesn’t consider the possibility of being hit with a huge asteroid in the middle of the problem.

 

3 hours ago, Sensei said:

ps. Kinda similar "problem" to "why to buy computer/TV/mobile/electronic device/car today? Tomorrow/after week/month/year the same product will be cheaper and as good as today". It ends with endless loop, if there is constant progress.

Sure. You need to consider other things in your decision. No claims to the contrary were made.

[dimreepr]

3 hours ago, Sensei said:

ps. Kinda similar "problem" to "why to buy computer/TV/mobile/electronic device/car today? Tomorrow/after week/month/year the same product will be cheaper and as good as today". It ends with endless loop, i thefre is constant progress.

Kinda depends on what one needs today, and if constant progress is possible with the occasional hit with a huge asteroid.