Is interstellar travel possible? - with Les Johnson

[@Alterraboo]

Finally an online speaker with a decent microphone. So many of these digital talks are unbearable to listen to

[@aliahammedshawon9152]

😂 True

[@edgeeffect]

If that's a decent microphone, I dread to think what a "bad" one sound like.

[@bealotcoolerifyoudid7217]

​@@edgeeffect exactly

[@bentucker2301]

What on earth have you been watching. This mic is terrible.

[@Alterraboo]

Just listen to some of the other talks. This one is tolerable. The other ones are downright awful.

[@monte21228]

From a person that doesn't know math or space science, thank you. I loved the graphics you showed, especially where our solar system is in our galaxy. You explained things in a clear and concise manner. I learned so much from this video. I've saved it and will watch it again and again. You made a difference in my mind. Thank you !.

[@mathew00]

What a great comment!

[@pking39]

@TheEarthStoodStill Well he just gave you his example and there are many examples or presentations to demonstrate scale of planets and stars. You don't have to be an ars...and snob to criticize others. I really want to see a snob like you invent or explain physics to normal people.

[@georgehenderson7783]

@Flyweight.8 Would you agree that the distance from Earth to Proxima Centauri is 266,000 times greater than the distance to our sun? That's what it said in the video I was watching right before this.

[@acesofcayde7949]

This was first class. Thank you so much to Les and to the RS for making it available online. Both rational and INSPIrational 🎉

[@korswe]

One of the best presenters I have ever heard. Thank you, Les!

[@artdonovandesign]

Without a doubt, one of the finest, most intriguing and informative lectures on KZbin. Thank you, Dr. Johnson!

[@KWW0321]

He's one of the best! His paper with RM Young on recent developments in solar sail propulsion is amazing!

[@owaisahmad7841]

Brilliant. Clarity of thought and crisp delivery! Thoroughly enjoyed every bit of the lecture. Great learning experience. What a noble career goal!

[@michaelsommers2356]

What I never see mentioned in discussions of interstellar travel is maintenance. We don't know how to build large machines that can operate for many decades without maintenance. Some large sea-going ships such as aircraft carriers can last for a few decades, but they spend a large part of that time in shipyards. There are no spaceship yards between here and Alpha Cen. A spaceship making such a long journey will almost certainly break down along the way.

[@808bigisland]

The alien vessels I seen are the same as in the year 1561 and 1566. So, yes , alien space tech can be maintained over centuries and possibly eons.

[@sarcastaball]

​@808 Big Island tf u talking about

[@fukpoeslaw3613]

There's no barnacles in outer Space and hardly any salty water so that's a pro .................

[@baarni]

@@808bigisland you delusional buddy…😂

[@jhbreytenbach1977]

Voyager 1 & 2 would like a word with you...

[@notmyname327]

This was really informative! I've always thought interstellar travel was impossible, now I think it's just really, really hard.

[@gwh0]

Thanks for sparing me the necessity of listening to him drone on for an hour.

[@vicvega3614]

Its impossible, we would need to increase our life expectancies to about 100 thousand years or we could just take off and try but then eventually there would be a spaceship flying around with dead bodies in it.

[@williamsparks1036]

The first sane presentation on space I have found. I learned a ton of facts that were new to me. Thank you Les Johnson.

[@issyjas3309]

It’s very good, have a listen to Lex Fridman, he gets some brilliant people to interview

[@ChrisM-tn3hx]

The one thing this didn't mention was the damage that even a microscopic particle could do to the payload if it was struck at 1/10th the speed of light. Hitting a single speck of dust could be devastating at that speed. Let alone the difficulty in threading the needle between all the celestial objects in between, each of which are moving on their own trajectories at high rates of speed including millions of small objects we can't even see or detect.

[@megafauna8374]

Agree. An interstellar vehicle would need some kinda ablative shield at the pointy end for running into molecular sized stuff and plenty of (water?) shielding from particles.

[@MySamurai77]

Yeah i agree first thing i thought. A giant 1 kilometer sized thin sail would get wrecked up there.

[@warpeace8891]

Yes, there are many Hazards, The biggest hazard for humans has always been other humans. Even if we can get everything else right. I have very low expectations that any group of humans could carry out a 1000 year mission without 100 wars and 1000 other human made drama's/catastrophes guaranteeing failure. They are just as likely to change their minds halfway and try to come back.

[@808bigisland]

We ve seen an alien ship that can be considered a relativistic coaster. At least half of the ship construction is designed as an “ablative” shield.

[@vicvega3614]

​@@warpeace88911000 year mission? 😅 humans cant even go 10 seconds without destroying everything, in the last 100 years humans have turned the earth into a smoking septic tank

[@maypenja2819]

I became an instant fan of Les Johnson when he said that he had read the Perry Rhodan series as a kid. I did the same from middle school to early high school back in the 70's. I have never met anyone who has ever read that series. I like the realism of Johnson's Interstellar travel lecture. None of the fantasy stuff from science fiction of which I am a fan.

[@TheRoyalInstitution]

Watch the Q&A with Les here: kzbin.info/www/bejne/gYqzmJqZh7N4esk

[@fwd79]

Pin it to top please.

[@zapfanzapfan]

+1

[@MrTimetravler]

This was very good thank you LES!!!!

[@lionelfischer8240]

You need as much energy to decelerate as to accelerate if you want to land safely once arrived.

[@RWBHere]

A Solar sail would be useful for interplanetary travel, but when you travel further away from the Sun, the acceleration will diminish according to the inverse square law. It will be essentially zero by the time it reaches interstellar space.

[@ClemensKatzer]

Yes. I guess the idea is, that by that point the vehicle has reached the 0.1c (or whatever it be) and from then on travels with constant speed. (Not sure whether the occasional hydrogen atom it encounters will slow it down "a bit".)

[@SeattlePioneer]

This objection was actually covered in the video. The workaround was the bright idea of using something like the total amount of electricity generated in the world to power masses of lasers which would focus light energy on the solar sail. Not a WORD about how the world might react to having it's total electricity supply grabbed up by NASA. Of course, when intellectuals are dreaming up their little projects, no thought is given to the ethics of grabbing up resources from human beings need be considered.

[@Fubar007]

Imagine being the guy who made possible the interstellar travel.. imagine being the guy who would appear, like Les said, in a history book from another planet in another solar system... That would be unbelievable awesome.. nice career goal.. truly inspirational video, I cannot wait for my son grow up a little and present him this kind of videos.

[@resofactor]

I'm here.

[@Video2Webb]

SO enjoyed this video! Les takes us away into the universe and says - Life is GOOD - Yes, it is. It's beyond good, it's miraculous and we can perhaps spread it elsewhere one day. It's fine to dream - and to be super engineering-minded simultaneously.

[@JAYFULFILMZ]

I remember as a kid, I used to think stars were just little specs of light that you could touch in outer-space lol I remember the day in school that I found out that those specs were actually distant sun’s just like our sun but super far away & you could never touch them! I was mind blown 🤯 Even today when I explain to other people that don’t know about space that those specs of light you see in the sky are actually distant sun’s just like our sun! it’s always fun to see them be mind blown just as I was all those years ago ☀️💫🚀🌎

[@AruChanWZ]

I was waiting for the problem with small rocks and dust. On high speeds they become pretty destructive!

[@Troeltsch7873]

I was waiting for the problem with interstellar gasses.

[@klowen7778]

Yep, the Oort Cloud alone, the cosmic junkyard of dust, ice and other assorted debris which surrounds the entire solar system, is estimated to extend at least a full light year... and even if we can successfully navigate that without running into anything at near light speed, it still doesn't count having to enter the _next_ "Oort Cloud" that's also likely to enclose Alpha Centauri's own system. And BTW, in all these discussions re: the 'speed' required, what about the time and energy needed for 'deceleration'? Bottom line, maybe the answer to the Fermi Paradox is simply that _magnitude_ of the problem of interstellar travel is ultimately just too insurmountable!

[@garypeatling7927]

But space is space I read, it is incredibly empty between us and alfa centory there only 10 particals within a mile of our route ( in a scifi book I read ) you could be unlucky and a meteorite leaves a bit of its self behind

[@AruChanWZ]

@@garypeatling7927 yes, but there are 23.5 trillion miles between us and alpha centauri. Multiply it by 10 and you get 235 trillion particles. Coming at you at tremendous speeds. A grain of sand can end your journey. And smaller objects like atoms and molecules will heat your ship and it will melt far before it reaches its destination.

[@stanscharlin2426]

Good question, I was waiting for someone to ask it.

[@neilevans160]

That was superb. A really understandable explanation of the science, the background, the current thinking, the challenges and the possibilities for interstellar space travel. Very thought provoking. Thank you Les and all involved.

[@whirledpeas3477]

I love analogies that explains how crazy huge the universe is. Thanks Les and R.I.

[@whirledpeas3477]

@KLJFcallme awesome 👌

[@rsr789]

@stafus You can't imagine the distance anyways, not in any realistic fashion: we didn't evolve to think that way... and he even pointed it out at the beginning of the presentation. Look at it inversely: how many can fathom the quantum realm in terms of distances between say the electron and the proton of a hydrogen atom?

[@rsr789]

@stafus It's a human issue, not a personal issue. STOP LYING to yourself.

[@rsr789]

@stafus Ok, we are done. You have just gone into fantasy land.

[@alexcarpenter5476]

Thank you, Les. Outstanding and inspirational presentation. Thoroughly enjoyed every minute!

[@Njkk500]

I thoroughly enjoyed it too!!

[@bertharius9518]

Les, the velocity required for interstellar travel; would this not run the risk of colliding with miniscule - almost invisible - particles in space that would have devastating consequences? Or would the odds of that occurring be extremely remote? Travelling at 16,000 miles in one second, I'm guessing that even some kind of radar device would fail to detect these particles in time to avert disaster.

[@davidgatzen1543]

If you are interested in how micrometeoroids affect spacecraft you might want to do a search for "micrometeoroid JWST". Because of the JWST's large mirrors and open design NASA has been concerned about micrometeoroids hitting JWST, and there are articles and papers about the affects of micrometeoroids hitting JWST. I have read that NASA has detected micrometeoroids hitting JWST, and there has been minor damage. For more detailed information search for "micrometeoroid JWST".

[@stargazer4023]

These are precisely the thoughts that keep me awake at night. The collision problem and the snails pace of light speed when compared to the vast distances. Solar sails etc. aren't going to cut it. We need to discover new physics that allow these limitations to be overcome.

[@ianseaweed]

Daughters school project, ‘make a model of the solar system’. We made a book, the scale we used was a biro dot for the earth, which in real life space has a diameter of 8,000 miles. After about fifty blank A4 pages we got to Mercury, did a pin prick and one hundred blank pages in did a pencil dot for Venus until finally after another 150 blank pages we did a biro dot for earth. It’s about another 4000 blank pages until one can a sharply dot down for Neptune which is only a third of the way to Pluto, but we got the point by now. Space is big even on a tiny scale.

[@havensule1644]

It sure would be interesting to see how far we have gone in say 100, 500 or 1000 years. I feel robbed sometimes that we have such little time to be alive. Thank you, very interesting.

[@MuzixMaker]

I was 10 years old when Neil and Buzz walked on the Moon. I thought it was a given that someday I would do the same. Unfortunately that won’t happen. Definitely feel robbed.

[@igorschmidlapp6987]

We have to get started on the arkships! We only have about 15 billion years before the Sun expands to a red giant and consumes the Earth's orbit! We gotta' get outta' here! ;-P

[@lancethrustworthy]

By that time we will have 'grown up' and with centuries of ever-advancing technology we will decide what we want to happen. We'll be able to rebuild or replace the sun. @@igorschmidlapp6987

[@lancethrustworthy]

Agreed. AI and quantum processing are going to bring about wonderful changes. Will the house computer eventually learn to read brain pattern commands? I hope to see cars as 'push button and go' reliable as elevators, more so, even.

[@discombubulate2256]

it's just a matter of figuring it out. throw enough money and resources at a problem and you can get there pretty quick. look at space x :)

[@MishMash22]

I can't believe how easy it was to follow. And I have zero knowledge of science. Thank you Prof!

[@Slikx666]

So many questions, so many answers, so many miles. 👍

[@jimmyzhao2673]

The Interstellar Symposium sounds like a lot of fun, especially in Montreal, that great cosmopolitan city !

[@warpeace8891]

Outstanding presentation Les Johnson, Thank you for sharing. A 1000 year trip to another star system, dramatically limits the mission purpose. The only reasons I can think of that would justify the resources is to colonize or perhaps to accept an invitation. There are far more desirable destinations within our own star system for colonization. An invitation would be impossible to ignore but easy to reject. Human collective decision making is not our best attribute. Interstellar travel is very far down the list of priorities from a practical perspective and it would not be a simple scenario to have an invitation from E.T. force our hand.

[@rogerphelps9939]

The only place in the solar system that can be realistically colonied, other than the moon, is Mars.

[@warpeace8891]

@@rogerphelps9939 I like Earth and for the rest of this century at least, we should be far more focused on surviving well here. Private funds are different... go for it Billionaires. Get the fck away from the rest of us asap please.

[@mrspaceman2764]

When it comes to space travel, more Johnson has always been the way forward.

[@daveac]

Enjoyed that - one foot firmly on the ground but with an eye towards a long term future. And for the SF fans, maybe half way there we get 'Hello, we were just on our way to see you' ;-)

[@semorgh2854]

yes you Enjoyed it for sure, because you think like Mr. E (Einstein) . Einstein thinking was limited 3 state of Matter and had no clue how powerful is the 4th state of the matter (Plasma).

[@TMHandAI]

Finally a great cosmic mind guided by moral class... It is incumbent upon manlind to share the gift of life. Keep up the good work!

[@laderidder]

I love your take on the ethics of not visiting a planet which even contains an amoeba but what if this means we only have access to dead/barren/inhospitable planets - this could make terraforming potentially far more challenging, if not impossible

[@Troeltsch7873]

To say the least.

[@Enonymouse_]

Terraforming would be highly dependant on planetary conditions assuming we even manage that kind of tech, people talk non-stop about mars but mars is a horrible candidate. Thin atmosphere and low gravity, the latter is significant since the gravity of our planet is key to trapping gasses that make life possible. On mars, its so weak the gasses would escape into space. Whatever space humanity inhabits would need to mirror its own or match it closely for gravity because our bodies have evolved to earth's own gravity field, our joints, bones and other soft tissues would deteriorate faster in a heavier atmosphere.

[@gaoxiaen1]

If a planet could only support amoebas, it wouldn't be able to support mammals, but might be suitable for terraforming.

[@piratessalyx7871]

Look how much debris is in our outer atmosphere, on the moon and now on Mars…we leave trash everywhere

[@Rudhamstile]

I have been dreaming of the possibilities of interstellar travel for most of my life, however Ive just realised that its really quite silly. Rather than waste time figuring out how to fling some unfortuate souls into the abyss, we have much better and easier things to do in our own solar system. Unfathomable wonders and riches lie within our current technologies and lifetimes right on our cosmic doorstep🙂

[@showmewhyiamwrong]

As I was listening to Les speak and go thru all the possible Modes of travel I kept thinking to myself..."Ride the Light." As to the question of whether or not we should even leave the Earth someday, here is the thing. Everything has a lifespan and that includes the Earth and our Sun and for absolute certainty when Our Sun goes thru its Death throes if the Earth is still around and has life on it the Earth will also die along with all life, as we know it, whether we are there to bear witness or not is up to us. Its not a matter of "if we should leave" but "when we should leave". To suggest otherwise is to make the determination that We as a species along with every other Species that exists or will exist on earth is unworthy to survive.

[@christopherellis2663]

Survive? How, where? You talk effeminate nonsense disguised as bravado 😅

[@davehoward22]

Life on earth will end long before the end of the sun,and the nearest habitable planet could be a 1000 light years away,if you could find one.

[@socialmeaslesinpartnership1252]

@showmewhyiamwrong is overlooking some things. The dinosaurs lasted many, many millions of years before going kerblooey. Man is one of the youngest species on the planet. There's therefore little evidence that the opposing thumb and abstract intelligence that uses symbols and externalises morality is any key to evolutionary survival - rather the reverse. Dinosaurs survived by-and-because if they weren't ripping everything to bits they were running away from something else ripping everything to bits. Mankind's self-perceived and self-inflicted idea that nature has anything to do with "Him" is a chronic, massive and necessary delusion but it's very, very unlikely that he will survive as long as did the dinosaurs. Man does stuff like "going vegetarian", getting hung up on which toilet to use etc..... all kinds of stoopid moral dilemmas that inhibit survival - abstract intelligence isn't necessary and it's quite obviously not doing us a lot of good. Everything else just.......rips everything to bits. Nature, Creation, Reality - call it what you will but it has no need of Mankind and we won't last long enough to fill other planets with rusty motor cars and defunct cell 'phones.

[@cosmodradek]

Just as you have to accept your personal finitude, the same goes for the species. Eventually, humanity will disappear completely. Probably way before the dying of the sun. Way before.

[@themarksmith]

Excellent talk - thank you!

[@Cannonquail]

Very good presentation! Love this stuff

[@darren5472]

The problem with this objective is not what scientists know but what they don't know. This very detailed talk demonstrates that current physics is not going to achieve the goal. The task requires bigger thinking, there is a solution to every problem, the problem is we don't know what it is yet. Looking in the same places for a solution is clearly not going to provide a solution. When you lose your keys, you look everywhere, and then then same places again. The keys (the solution) are never where you think they should be. What is clear, the concepts that will achieve travel over these distances will not be limited by current physics or science. We need to be brave enough to look outside of current understanding and accept failure/learning is part of that process. A very informative talk, thank you for sharing.

[@BudryBoy]

I love the content on this channel, very inspirational. thanks for sharing!

[@LCThompson]

This is the most definitive and comprehensible discussion of inter-stellar travel that I've seen.

[@OraDeCulcare]

The discution is mostly about the acceleration part to the target system, but you cant study or see anything when you reach that solar system going trough it at 10% C . The probe should start decelerating at about halfway. Then the trip takes longer than the scenario in wich it is coontinuously accelerating

[@anarghyasinha]

Thank you for this video! Really wanted this for sci fi facts

[@lohphat]

22:22 Thy have not exceeded break even for fusion. They only exceeded the energy injected into the target but that’s nowhere near the energy needed to power all the lasers to create the burst pulse itself. They’re only 1/400th of the way to generate the total energy needed. They’re not even close. Sabine Hossenfelder explains this on her channel.

[@artswri]

Mr Johnson, may you and your life energy become a Large Part of that someday-history. Thank you for sharing and elevating my world view and understanding... And particularly for incorporating ethics and morality as an integral part!

[@Splarkszter]

Extremely awesomely interesting.

[@spitfire2885]

Best video i seen recently on youtube ..excellent work

[@bladeofzorro1932]

This was great eye opener to the possibility of space travel in the future. However, there's only 2 questions I would like to know the answer to. How do you slow the space craft down, going at the speeds needed to cover those distances? Won't this need a great deal of extra time and energy? And going at these speeds wont the dust and small particles destroy the craft.? Are there system in place to avoid this?

[@jerrypolverino6025]

To slow down we would just turn the craft 180° and employ the same propulsion system. Yes, slowing down would take close to, or more time than it took to accelerate depending on the relative velocity of the target.

[@stellerpleb.6530]

Very well done. Easy to follow.

[@rahinc]

Just don’t take kids on your trip to Alpha Centauri. For the first 15 years you would hear them repeatedly ask “Are we there yet?”

[@pluto9000]

Leave the kids on Earth ? 🚀 🌎

[@eta2380]

That was only relevant before the digital age. Now, the kids can just check their phones GPS to find out if they are there yet.

[@josephm3966]

Not if your a smart parent who doesnt allow their kids to have their own phones. ​@eta2380

[@kevinflick61]

This is one of the best videos I've seen on the idea of interstellar travel - very informative and easy for someone like me to understand who has no background in science but has always been interested in knowing everything I can about science.

[@matthewmatt5285]

LOL~ I'd love to see the Worst one,...~

[@AndySpicer]

I don’t see this happening unless we discover some physics we don’t know about that allows the trip to interstellar destinations in a year or two. And the truth is, any physics that allows travel that quickly will probably make the trip roughly instantaneous.

[@mokujin29]

Even then , the mettalurgy , the massive energiies which would be needed , all beyond Human comprehension. Humans are bound to the earth's Bioshpere

[@marktime9235]

​@@mokujin29 we have been to the moon y'know? 😊

[@AndySpicer]

@@mokujin29 I think we will eventually figure it out but I suspect that it will be some sort of manipulation of space time or dimensional geometry, or some other thing that we don’t understand yet.

[@JohnSmith-qq7yw]

My thoughts exactly. I'm still banking on the Bob Lazar method becoming reality some day. Discovering the true wave nature of gravity and the strong nuclear force. Using anti matter as the energy source to Amplify the strong nuclear force to create gravitational fields to warp space and essentially create the alcubierre warp drive. And as you said, when such physics, or any other physics of this kind is discovered, getting to the stars will be virtually instantaneous. Otherwise, this guy talking about solar sails, and a 1000 year journey to the nearest star is a complete joke. What happens if the closest inhabitable planet we find is 50 light years away? With this guys thinking, it would take 10000 years to get there. We aren't going anywhere until a new kind of physics is discovered. It's as simple as that.

[@K1lostream]

Even if you could do it in a year or two, that would only be a year or two for you. By the time you got home two-to-four of your years later (plus however long you stayed) everyone you knew would be long dead.

[@louisebean9428]

Sending cameras into space, attached to a computer and solar sails, is the best way to explore the universe in any direction!

[@brent57]

Excellent presentation. One question I had is what do we believe the chances or possibility of colliding with something floating in interstellar space as we travel at 10 percent of the speed of light? It seems that striking even a grain of sand at that rate would be catastrophic for a traveler.

[@Troeltsch7873]

Maybe something resembling a very oversized hardware cloth could minimize the amount of destruction you would get from a grain of sand at that closure rate?

[@vicvega3614]

​@@Troeltsch7873just cover the whole spaceship in flex seal it would be indestructible

[@Troeltsch7873]

@@vicvega3614 Oh dear.

[@vicvega3614]

@@Troeltsch7873 might work, they made a submarine out of that stuff 🤷‍♂️

[@stanleybuchan4610]

Despite being a sci-fi fan as a kid (original Star Trek on TV), the more I realise the distances involved, the less chance I think we have of getting anywhere.

[@piratessalyx7871]

Maybe its set up on purpose, so no civilization can corrupt or takeover another 🤔

[@sakismpalatsias4106]

Out of curiosity. Could you replace negative matter with constant controlled expansion of new space? Similar to what may be occurring in the intergalactic medium?

[@chadenright]

You might be able to get some interesting effects by putting a black hole on the prow of your ship. Or maybe not. We don't know how to do that either, though.

[@AdrieKooijman]

Not likely. Space expansion is very difficult to control and making new space even seems to be impossible. Negative matter is found on social media, but there's no known method for any practical application until now.

[@lambeausouth1]

Your talk with Freeman Dyson is one for the ages as they say! What an incredible opportunity!

[@briankepner7569]

I think we need to have a really good reason to put people at such risk. They would definitely have to be volunteers because it's probably a one-way mission

[@frankbarnwell____]

Earth is pretty risky, too

[@AndySpicer]

The people who volunteer to go will decide for themselves if the risk is worth taking.

[@jimgsewell]

@@AndySpicer No, a 1000 year trip means that they make the choice not just for themselves, but also for 200 generations of their descendants.

[@georgesos]

​@@jimgsewell so? Who cares about the offspring of elon and Bezos. My problem is that they(as parts of the economic system)are destroying our chances for survival on earth. Longtermism is an unethical philosophy, equally sick with eugenics (aka nazis).

[@AndySpicer]

@@jimgsewell nobody is setting out on a 1000 year trip. Those would be robotic missions.

[@DwainDwight]

Les, this an area close to my heart and glad to see this terrific presentation. If we really want to explore our galaxy we have to think of travel for 10s of 1000s of years.

[@kaseyboles30]

There is a theoretical variant of the Albecurrie drive doesn't require negative mass or energy. It is limited to sub light effective speeds so still over 4 year to alpha Centauri, and it needs massive amounts to energy, on the order of tons of antimatter being used to generate it. That said the original Albecurrie drive had it's energy needs reduced by better calculations from nearly the mass energy equivalent of the milky way down to that of a small moon/asteroid. If they can make this variant work on more reasonable amounts of energy there is some hope for exploring the nearby stars. Perhaps even colonization of the nearest few.

[@PointyTailofSatan]

To my astronomy challenged friends, I found a way to help them understand these distances. Imagine an American football field. On one goal line, place a quarter coin. That roughly represents our solar system out to Neptune. Now, on the opposite goal line, place another quarter. That represents the Alpha Centauri system. This not only makes it easy to visualize the distance, but also shows the incredible emptiness of interstellar space.

[@PointyTailofSatan]

@KLJFcallme You can't visualize 20km. My way, you can see both systems and the distance between them at the same time.

[@TomLeg]

Concerning "Les's Prime Directive" .... A volcano produced a new island near Iceland in 1964 (+/-). It was declared off-limits, scientists only. After a couple of years, they found a tomato growing on the island. A closer examination revealed it was growing from human poop. A scientist shat out his lunch, including a tomato seed that passed through his digestive system, and sprouted. Demonstrating that it is VERY hard to maintain a pure environment.

[@NerdishNature]

Awesome. Saw Les on the eve online fanfest 2014 (!) talking about the very subject. Great to get an update!

[@apstrike]

This seems to miss a big point: we've not yet found anything like another Earth to go to, not within 10 - 40 light years. Nobody wants to go live in a dome on a planet that lacks gravity, is tidally locked,or has the wrong spectral type. I think we fool ourselves with constant reference to Alpha Centauri. We will have to journey much further out to find an exoplanet that offers dramatically more than what we already have on Mars.

[@rockets4kids]

You're not wrong, but the context here is unmanned fly-by missions. It's a much more difficult problem to decelerate and orbit another star/planet. And then a vastly more difficult problem still to send humans on that mission.

[@EuphoricDan]

@@rockets4kids Proxima Centauri B is probably fine. If the effect of it being tidally-locked makes the surface area that can be most-easily lived on less I mean, so what? All planets are like that. The Earth is like that. Most of our surface area is ocean and then the polar regions are inhospitable. Proxima Centauri B could have just as much livable surface area as the Earth depending on it's conditions.

[@abhijitnaik1695]

What a wonderful lecture / talk !! 💐💐

[@recklesswhisper]

So! Freeman Dyson wasn't all that embarrassed after all! Great story! Amazing informational talk!! ^..^~~

[@YersiniaPestisNPO]

Wow what an amazing presenter. My imagination is brimming with the possibilities of sailing through space!

[@ubserrano8180]

It is just sad how a person of science fails to apply logical and objective thinking to man made up stories like gods, conceding it an undeserved exemption to those processes. Anyway, great talk, those examples for distances were very clear.

[@istvansipos9940]

a Cold War American well indoctrinated into "da Lawrd" idm. But yeah, it is sad that he had to mention the magical magic of the never seen g0d in a scientific talk.

[@TrynePlague]

Distances in space are just crazy.. one thing that I found crazy is that you can take every planet in our system and place them all next to each other between Earth and our Moon and you still have some space left.

[@dr.patnesbitt]

The thickness of a human hair is about 70 microns, not 2.5 microns. Which makes your sail even more amazing.

[@mskellyrlv]

Nice video. One comment is that Freeman Dyson was never "Dr." Dyson. He never got a PhD, and was, I think, the only person working at the Institute for Advanced Study who didn't have one. I don't blame you. I worked as a DARPA Project Manager for a time, and regularly got the field promotion to Dr. Kelly, but I have only a Master's. Your meeting with Mr. Dyson was amazing. I met him very briefly when he received his Arthur C. Clarke Lifetime Achievement Award in 2011, but can say I have shaken his hand. I would love to have heard his reminiscences about Project Orion.

[@andyh3873]

This was a really informative video, thanks! It's great that in the future there might be ways to speed up the travel between A to B. What about slowing down though, once one approaches B?

[@iambiggus]

The most efficient method is to flip the craft and fire in the opposite direction mid flight.

[@philshyu5248]

Or how to take evasive maneuvers if one encounters a cylon raider or imperial tie fighter intent on shooting you out of the sky on your way to Alpha Centauri. 😂

[@Troeltsch7873]

Yea.

[@michaelhall2138]

Our science and the thirst for knowledge is the best of us.

[@lavie403]

Q.: Is there no contradiction between extending the possibility of survival of the human race, and not (for ethical reasons) inhabiting the habitable planets (i.e. inevitably with a form of life, such as water, soil, plants and all that goes with it)? I understand it's not impossible with terraforming, but I don't see how it will happen in reality...

[@bailahie4235]

This engineer/scientist Les Johnson points out so clearly and inspirationally why you should pursue dreams that are shamelessly big.... (In his case, figuratively and literally ;-) )

[@chadenright]

Solar sails can absolutely let us send a probe to Alpha Centauri, but it's going to be a lot more difficult to use sails to send a minimum viable colony of a few thousand people and a Noah's Ark of animals, vegetables and minerals, all of which need to survive a hundred-year journey before they can set down roots. We almost certainly need to figure out near-space colonization of the moon and mars before we worry too much about interstellar colonization, even if we find some superterra in a goldilocks zone with liquid water, a breathable o2/n2 atmosphere and a near-earth gravity where we could simply wander over and set up shop.

[@istvansipos9940]

by the time we can build such ships, we can build any space habitat we want. A nice planet will be nice, but it won't be necessary.

[@Safetytrousers]

We may have figured out how to upload ourselves to computation devices by the time it is imperative to leave. And then humans can just exist in space.

[@chadenright]

@@Safetytrousers If you think security issues on your pc are bad now, just you wait.

[@Safetytrousers]

It doesn't stop Charlie Brooker.@@chadenright

[@kmolnardaniel]

yt recommended me this, and wow, what an amazing presentation

[@marcomattano3705]

Nice video, excelent topic.There are other options that you didn't mention and I'm really curious to know your opinion on them.aybe viable, absurdly huge engineering and technologic challenges, but Physics law abiden options: - Bussard RamJets (maybe just as an additional propulsion systyem, if you're travelling that fast it would seems advamtageous to collect extra reraction mass). Somewhere on the internet theres an aerticle with calculations saying that the forward maknetic field would need to be 150 million Km, ou 1 AU, so almost impossible, but maybe on the central part of the galaxy with a higher Hidrogen ISM density. Imagine the beauty of it!

[@mattvjmeasures]

I guess though that the faster you're going the smaller your particle collection field would need to be? Because you're "sweeping" through volumes of space more quickly.

[@marcomattano3705]

@@mattvjmeasures up to some point. The closer you get to light speed, the more 'reaction mass x mass ejection speed' - or power - is necessary to accelerate, and it increases exponencially I guessd, I'm no scientist. After some point the acceleration from the collected matter would be a good thing - free gravity - but it would make no measureable difference to the ship's speed I guess.

[@Member_zero]

Yeah - but that's theoretical at best. He was talking mostly on technology we can start developing now I guess. I personally think solar sails are good - they are already available and solid for visiting our first star. I think in about 100 years or even less it's realistic to send a mission like that. That's because propulsion is only the first hurdle. I think if we want to get further - at least to our backyard of stars, anti-mater is the best bet. I think it is inevitable that once we develop it, we will also get the new weapon, way stronger than nuclear bomb. And I think there's a lot of reservation about this. But we will have to swallow the pill. With no risk, there's no reward. Yes - there will be war in space in the future. I think it's inevitable - we are on the brink of it. So there's no sense in trying to prevent it IMO. Someday, an organization will knock a satellite out. And that's all it takes to start a space arms race.

[@CothranMike]

Yea! It's Les Johnson, my favorite scientist and SF writer. Welcome to the RI video cast. I've watched the RI casts for many years now and you are a welcome speaker here even if you are not there but here in the Huntsville Alabama area (Madison specifically). Great job, kudos to you. MikeC

[@CothranMike]

Going to view the Q and A now...

[@martindice5424]

The solar sail is great and a great Sci Fi trope - but how do you slow down when you get there ?

[@zapfanzapfan]

The light from the target star?

[@canadiangemstones7636]

Half your trip is deceleration.

[@danielh.9010]

@@zapfanzapfan "The light from the target star?" - Forgot about the lasers needed during acceleration? There are no lasers at the target star, which means that the solar sail will be insufficient to bring the space probe or ship to a halt (if the star's luminosity is somewhat comparable to that of our sun).

[@zapfanzapfan]

@@danielh.9010 Solar sails, not laser sails. If you are passing by Proxima Centauri at 0.2 c you are not stopping...

[@TheNicoliyah]

Thank you!🙏I enjoyed every minute of that. Really complicated science explained in a way that even I can understand.

[@issyjas3309]

Brilliant podcast, learnt so much. The one question I’d have regarding the light sail is that , a:it’s very large b: it looks very fragile so c: how would it cope travelling at those speeds and potentially hitting space debris ?

[@Troeltsch7873]

If you had been dreaming up very big radiators to cool a thermonuclear propulsion system then by the time you get over to the light sail plan you say Pheww! At least a light sail is not going to leak your coolant out.

[@tradtke101]

Tiny things pass through, bigger things makes tiny holes in the sail. The small central payload is shielded heavily. You can also tack in your sails when passing through dense areas like the Oort Cloud or if your sensors detected a dust cloud or something like that. You'd also have basic thrusters to steer around stuff. But I think it's definitely an issue and that's what the intermediate solar sail missions to near interstellar space would hopefully help ascertain.

[@zapfanzapfan]

Very good talk. More near term goals to test the technology would be to catch up with Oumuamua, go to the Suns gravitational focus with a telescope or go to Planet 9 when it is found.

[@deanwcampbell]

So many people don't understand that pulse detonation is only beneficially feasible within atmospheric conditions. Detonating an atomic bomb in a vacuum by its self does not produce thrust. Matter is required to expand in order to produce thrust, in space there is no matter to expand.

[@carphone9385]

If you come across as even half-intelligent on these science comments section 90% of Americans immediately turn off as they do in real life situations - they go 'dead quite' when intelligence is in the vicinity. - 60% of Americans stopped on the street famously couldn't name a country in the world starting with the letter 'U'.

[@markcohen7991]

You are fantastic. Space, time and thought is my view. We are one world and one people. Your video is totally awesome. Live long and prosper 🖖

[@christalbert722]

I think the "prime directive" limitation would be a show-stopping problem.... My guess is that anywhere conditions aren't actively hostile towards life, we will find life... It seems likely that the kind of life will be proportional to it's complexity- meaning simple life very common, octopods we can play chess with quite uncommon. We wouldn't want to (and likely couldn't) colonize any world that is hostile towards life... meaning any real-estate we're interested in will likely have at least simple life on it. This whole "prime directive" approach *sounds* noble enough, but effectively limits us to lifeless rocks. That doesn't work. Probably doesn't even allow us to use mars. I hate to be all Darwinian about it, but any life we encounter- well, check it out of course, not be dicks and just exterminate stuff. Collect and study every good idea we find. BUT plant our flag, plant our crops, and do our thing. And hope when we meet up with those Octopods that we're interesting enough (and resilient enough and well enough dispersed) that we survive. (short story recommendation- "Dinosaurs" by Walter Jon Williams)

[@oc2phish07]

I was totally engaged by this inspirational video. Well Done Les.

[@brettmeikle]

Jings, he kept that 'God's Providence' bit quiet right to the end, or I'd have been out before clicking play.

[@tomamberg5361]

Oh no! Someone who deals with the reality of the Universe believing in a Creator of the Universe! The horror of it all… I'm so happy you were able to avoid a temper-tantrum. God Bless!

[@rudihoffman2817]

What a fascinating and credible explanation of the realities of star travel. Great programming, thank you!

[@matthewmatt5285]

Astonishing,.Incredible,.mesmerizing, unfathomable, magnificent, marvelous, spectacular,.,. ,..DUMMIE~

[@evifnoskcaj]

We'd have to use an Alcubierre Drive or some sort of similar technology that warps space-time. Our best hope is, even like in Star Trek, is hoping that we will find a naturally occurring Einstein-Rosen bridge (wormhole).

[@semorgh2854]

You are as bad as this LES guy!!!!!!! you are stuck with that stupid E=MC^2 of Mr. E. which does not do any damn good for humanity.

[@evifnoskcaj]

@user-pw2ro7gt4r Agreed

[@johndoepker7126]

Wat a phenomenal talk....got my lil grey cells thinking, not if but when !!! Helluva thing to think about!!

[@kevinsayes]

Awesome video, thanks. Personally, and if true, unfortunately, I don’t think we’ll ever tackle meaningful interstellar travel. I’m sure at least one of our probes will happen to intersect with another star system as it floats through the void, but nothing intentional (a probe that we send specifically to a star to get info back).

[@mayflowerlash11]

I agree. The difference in difficulty between supporting human life in space and just collecting data and sending it back is enormous. We will send probes long before humans venture into interstellar space. In fact if we do send humans it will be in a spaceship large enough to support a mini earth environment with enough humans to be a self sustaining population. Future generations will arrive at the next solar system after the initial and earlier generations die. This means the initial travellers will not get the reward of arriving at the destination, but they will have the satisfaction of knowing that their descendants may get there.Humans have done a similar thing previously. Travellers left their homes and families without knowing when they would or if they would return.

[@aerozg]

Can we stop and appreciate the fact that to explore our planet Earth, the early adventurers used sails (on sail ships) and now we are doing the same to explore the Universe. Amazing.

[@LexPips]

Very nice scientific presentation LJ although as a scientist how is it that you truly believe the so called miracle of earth is due & caused by “Gods Providence”?

[@Rbg1542]

May I suggest Is Atheism Dead by Metaxas? That may answer your question.

[@galacticgaming1552]

What Prevents the sail from being destroyed by something in space? By The Way this talk was amazing

[@themiddleman781]

This man is a genius. He's figured out how to get paid to travel the world to discuss something that will never happen

[@semorgh2854]

I really think you have figured this guy out for sure. Out of all the comments I read, Yours is the most LOGICAL one. The problem with people that have their PHD in this field is to produce Bullshit and get paid. And they are all stuck with that E=MC^2 formula, that is their hang up, they keep taking about 1000 Kilos of Anti-matter or 1 Million kilos of Hydrogen to be on the spaceship to carry them to the nearest Planet(Mars). They are making the biggest Tokamak Solar energy generator in France and spending 22 Billion Dollars by Now, to FUSE Tritium with Deuterium which has not worked yet. (personally, I think if that Tokamak does not FLY away once they start it they would be lucky, I literarily mean FLY (because you spin the H3 plasma that will create HUGE magnetic Field). The Practical Spaceship is the one that works with Plasma reactors, which has a 99.99 % efficiency, That 0.01 percent is the electrical energy to SPIN the electrical Motor of the Plasma container for generating Magnetic and Gravitational Fields. You cannot have Interstellar travels with any kind of Propulsion Engine, Must have Plasma reactors, which with their Magnetic fields they Interact with magnetic fields of stellar entities like Earth, Moon, Sun, and even Magnetic fields between Galaxies. I hope My material make sense to you.

[@istvansipos9940]

and you wrote that on a device nobody even dreamed of 200 years ago. Bravo. can you now go into the details and SHOW us why it can never ever happen?

[@themiddleman781]

@@istvansipos9940 Given enough time sure. But is there enough time?

[@ugiswrong]

Utilize that fast forward whenever he talks about traveling and it’s good

[@lilysceeliljeaniemoonlight]

1 AU= 1 little piece of gold class travel!✨🖖🧚💫🛸

[@SuparTuber]

Thoroughly enjoyed this. I will be getting your book!

[@SomeKidFromBritain]

Earth has bigger, more pertinent and far more urgent problems to solve.

[@rockets4kids]

On the bright side, keeping people alive on a spaceship for 1000 years is exactly the same technology which will be needed once the Earth's environment has been trashed....

[@SomeKidFromBritain]

@@rockets4kids nonsense. If we are smart enough to make such things, we are smart enough to prevent that. Stop being a doomer

[@rockets4kids]

@@SomeKidFromBritain Oh, I'm sure that given enough time we'll figure that out. The question is, will we still have an advanced society by the time we get to that point?

[@SomeKidFromBritain]

@@rockets4kids No idea what you are talking about mate.

[@rockets4kids]

@@SomeKidFromBritain Yeah, that's why I've got so little hope for the future.

[@Robert-nz3te]

Very mature well researched and delivered. Hope this gives inspiration to many. That there are some beautiful and forward thinking people still left in this world. I am onboard with you sir. Thank you.