Space will never be conquered! Sad, but true. Let me explain how I’ve reached this conclusion.

Image of Earth from Apollo 15

Big Blue: Earth photographed by the crew of Apollo 15 (Image credit: NASA)


Planet Earth is big! The furthest you can travel from home across the Earth’s surface is about 20 000 km (any further and you’re on the way home again). How long would it take to walk this? Assuming you can walk on water and land at a steady  5km/h for 12 hours a day, what do you think the answer is? Walking from side of the Earth takes 333 days. Imagine you’re a multi-billionaire and have your own Concorde. It will take you nearly nine hours to fly that distance. Spreading across the Earth and making it our own were easy; early humans wandered out of Africa about a hundred thousand years ago, now we’re everywhere!

Image of earth and moon

A pretty pair: Earth and Luna as seen by the departing Voyager 1 probe (Image credit: NASA)


The Moon is far away! If you rise from Earth you’ll have to cross about 380 000 km before you reach the Moon. Your Concorde will fly you there nonstop in just under a week (and yes, I know that jet planes can’t operate in space, this is an imaginary Concorde). Hope the inflight catering is good!

The Sun is far away! Travelling 150 million km from Earth to the Sun by Concorde will take you more than seven and half years.

Image of NewHorizons_Jupiter

The New Horizons probe swung past Jupiter in February 2007 its way to Pluto (Image credit: NASA/APL)

The Solar System is big too! There isn’t really a line in space that everyone agrees marks the edge of the Solar System, but let’s assume that Eris, the most distant known dwarf planet, is the last stop before you leave the Sun’s neighbourhood. On average it is 10 billion km from the Sun. Imagine you’re a multi-trillionaire and have bought your own exact copy of NASA’s New Horizons Pluto probe.  For the record, New Horizons is the fastest spaceship ever built (by Earthlings anyway, if you know differently please me know) It is travelling at 58 000km/h with respect to Earth (more than 25 times the speed of Concorde), launched in 2006, it will fly by Pluto and its moons in 2015. If you fire your private New Horizons clone towards Eris and wait for it to report back you will hear from it in just under twenty years.

By the way, all these examples are based on straight line distances. In practise you would fly curved trajectories to compensate for the movements of the planets so your mileage will vary.

The Solar System is pretty big. Eventually though we’ll get bored and look outside. Let’s go to the nearest star system to our own, the triple star system of Proxima Centauri, Alpha Centauri A and B which everyone knows is 4 and a bit light years away.

To be precise, the Centauri system is 4.36 light years away. “4.36 light years”, just rolls off the tongue, doesn’t it? Let’s convert it to kilometres, we get 41 trillion km. That sounds impressive, but just how big is a trillion? Start counting with me, a number every second, 1…2…3…4…

When we get to 600, ten minutes will have passed. We get to 10,000 and two hours 47 minutes have gone by, keep going, don’t stop!  A million seconds takes us 11.5 days.  By the time we reach a billion seconds more than 31 years have gone by. Counting to trillion, a number every second takes more than 31 thousand years.  A trillion is a ludicrously big number.

Let’s point the New Horizons probe at Alpha Centauri, start the clock and see how long it takes to get there. Expect a long wait!

Image of milky way galaxy

"My god, it's full of stars!" The Milky Way is about 100 000 light years wide and contains about 400 billion stars. (Image credit: NASA/CalTech)

The journey lasts 80 thousand years! While we sit waiting for our probe to call back I would expect us go through Global Warming, a zombie apocalypse then maybe an ice age or two, a robot uprising and probably by the end we’ll have evolved heads like space hoppers. And that is only the distance to the nearest star! The whole galaxy is 100 000 light years across and Earth is about 26 000 light years from the centre. Imagine we launch New Horizons towards the galactic core. Expect a journey time of 480 million years. If the Burgess Shale fauna had launched such a probe to the centre of the galaxy it would arriving now.

It is 13.8 billion light years to the edge of the observable universe and estimating travel times across this distance seems silly. Suddenly our Solar System is rather small and cosy by comparison.

And that is why we will never conquer space. It’s too darn big! I can believe that one day travel to the planets will be easy as travel between continents is today. Epic journeys to nearby stars may even be feasible, but treking across the galaxy or beyond will never be achieved by humans.


Gary MacDonald · August 8, 2018 at 17:01

Yes, space is difficult to travel with our current level of technology. Also, our current level of technology will continue to change, as it always does, to newer and better technology. There are really no limits to what we might achieve in the future. Our scientific understanding of this world and the universe around us is still in its infancy. In short, we don’t know what we don’t know, and what we don’t know is much greater than what we do know. Eventually we will develop technology that allows us to travel to other dimensions where the rules of time and space are different. Other civilizations in our universe have been using technology like this to visit us for thousands of years already. If you think we are alone in this universe you should know that there is plenty of evidence that we are not alone, you just need to do a little research of your own to prove it. The information you seek is available even through government websites.

    allison · March 2, 2019 at 03:26

    there are plenty of limits to what we will achieve in the future. the theoretical efficiency of engines, the energy density of matter, the bonding energy of molecules, the speed of light, the maximum theoretical lifespan of a human; all of these are hard limits that no amount of technology or optimism will budge by an inch. there is no special destiny for any species among the stars, and the universe doesn’t care if we succeed or not.

trevor · February 20, 2017 at 16:46

One thing everyone forgets is that if you travle at or near the speed of light if you encounter anything with mass you would be annialated ! And space isn’t empty.

Amar · March 19, 2016 at 21:58

For every travel we have to count the natural life of of earth and the sun. The universe cannot be conquered no matter how fast we travel. Still we don’t exactly know how large is the universe. What is sure for now is that the universe has no limit and edge. How far we have to go? To which galaxy? And what will happen back in our own solar system, particularly to earth, when we are traveling at the speed of light to cross only the Milky Way? Don’t forget the the special relativity when thinking and imagining all these possibilities. Human cannot conquer the universe because our life is prone to apocalyptic changes, but the universe is in constant change- destruction and construction. But I hope some day the human can find another form of life and intelligence within or outside our solar system.

Critter · March 30, 2015 at 04:55

Interstellar distances are tremendous. Whilst one can only speculate on what is possible or otherwise in the future, what is certain is that interstellar commuting is at the moment and the foreseable future practically impossible. Comparing technological achievements in the last 200 years, formerly regarded as impossible, with interstellar travel is like comparing the intelligence of virus with that of the human mind.

All this being said, one never knows what may happen in the distant future.

C · December 31, 2014 at 02:08

Never say Never

    admin · January 5, 2015 at 09:21

    I hope I’m wrong too!

George · November 10, 2014 at 03:07

The Lorentzian transformation (of Einstein’s STR) calls for relativistic mass accretion as matter approaches C. Among the many physiological effects this would have on a human, perhaps one of the more dramatic is the impact on just one organ– blood (yes, blood is an organ).

As you approach C, your blood’s mass increases (along with everything else, of course). As your blood’s mass approaches that of, say, liquid lead, your heart has to work harder to pump it. Unfortunately, there is no indication that muscle strength increases as one approches C. Consequently, any human would suffer complete pulmonary failure long before he/she ever got close to C.

Anyway, man will never come even close to traveling at the speed of light in a spaceship.

    admin · November 10, 2014 at 09:54

    I’m sorry but I don’t think you quite fully understand relativistic motion. The moving body’s mass does indeed increase as measured from external observers in a separate reference frame- but the body itself in its own reference frame does not experience this. The crew of ship travelling near c would regard their masses as unchanged and would not experience the dire consequences you suggest.

    I hope that helps.

      George · November 11, 2014 at 02:55

      You have no idea what you are talking about.

        admin · November 11, 2014 at 09:03

        Sorry, please explain.

          Peter · February 4, 2016 at 15:22

          admin is right. The relativistic effects are observed from an external reference frame, inside it, all is fine.

send in the jagdpanther · December 15, 2013 at 04:43

although your arguments here make sense you have forgotten one CRUCIAL factor: special relativity. although far beyond our current technology a craft approaching the speed of light experiences considerable time dilation allowing for a sufficiently fast vehicle to reach the galactic core in only a week of onboard time despite this taking atleast 25000 years for an observer on earth. so an interstellar empire is impractical but exploration across even millions of light years will be feasible once a powerful and efficient enough engine is developed.

    admin · December 16, 2013 at 09:41

    I agree, though relativistic travel is only a tiny bit less impossible than faster than light travel.

    You might enjoy this piece on photon rockets, I’m following it with a piece on Bussard ramjets in the new year.

    George · November 10, 2014 at 01:44

    Actually, you wold be dead from radiation before you reached the speed of light.

    allison · March 2, 2019 at 03:28

    and a single undetectable particle of dust will annihilate your ship with the energy of a billion atomic warheads. good thinking.

Alex · October 26, 2013 at 10:48

I don’t believe in NEVER. It’s just the way we think now. Some time ago there weren’t any cars, planes or relativity theory. It’s not possible now to travel to other start, but in the future, by developing new theories and technologies, it will be possible. Some time ago Jules Verne just imagined the future and now all of his stories came true. NOTHING IS IMPOSSIBLE and by putting NO in front of the sentence will limit our mind to think further. Leonardo da Vinci or Michelangelo never thought of IMPOSSIBLE.

Always me · February 2, 2013 at 20:57

agreed, we will never travel to another S O. To travel trought space we need magic more then science. The comparison whit Wright brothers or Colombo or Amerigo Vespucci doens t make sence, since those guys did expedition on a planetary environment, as hard was the expedition they still could count on breathing air, or still got the hope about find someone across their trip to help in case something go wrong. However, i really hope im wrong and some day before my life time end, someone show me the space travel, which i mean go in another solar sistem, it is possible.

    SpaceCadet · April 5, 2016 at 20:27

    I am excited to share with you the thought that humanity has been consistently incorrect about the basic nature of the Universe for the last 5000 years of recorded history.

    Good, functional technology comes from sound theory put into practice. What technology was spawned by crackpot full-of-holes theories of a self-eating snake, a flaming chariot for a sun, nested crystal spheres for the heavens with a flat earth below, or God’s insta-universe (Big Bang)? ABSOLUTELY NONE.

    When traveling underwater a very fast submarine has gone 52PMH and a supercavitating craft may reach hundreds of miles an hour. At least for now, it appears 800MPH might be a speed limit under water. Each new speed achievement is due to the AVOIDANCE of restriction by the medium one is forced to travel within. Want to go faster than 52MPH? GET OUT OF THE WATER. Can’t get out of the water? Well then, GET THE WATER OUT OF THE WAY through supercavitation and attain 800MPH. The X43-A reached Mach9.6 (around 7000MPH) using a combination of scram-jets, rockets and high altitude. The Falcon HTV-2 managed Mach20 before crashing into the sea. That is around 13,000MPH at the limits of our atmosphere! We could claim that as the current speed limit for air travel. Want to go faster than the speed of sound (~750MPH, slowing a bit at lower air pressure/higher altitude) in atmosphere? Shape your craft like a dart, and poke THROUGH the shockwave, and fly at ever higher altitudes, essentially avoiding the air.

    Interplanetary exploration probes are flying within our solar system at 36,000MPH pushed by chemical thrust and further accelerated with gravity assist fly-bys. Once you are in space, you are in a VACUUM, which accepted cosmology says is empty, so you can no longer get “anything” out of the way for higher velocities. Result? A technological dead-end is announced; Sub-light-speeds for eternity.

    When the true nature of a supposed VACUUM is understood fully, only THEN can new velocities be attained, because “it” has to be PUSHED OUT OF THE WAY OR AVOIDED.

    A bad theory results in zero technology. A transitory, inflationary, accelerating Universe is BAD THEORY, as it has resulted in ZERO technology. Dark Matter is a bad theory, as it has resulted in ZERO technology. Assigning special characters and names to imaginary sub-atomic particles linked to fundamental properties (gravity, mass, time) of the Universe has also resulted in ZERO technologies. Hubble’s explanation of Red Shift, Schrödinger’s superposition, Heidelberg’s uncertainty, Einstein’s relativity, Hawking’s “poof out of nowhere” Universe – these are all IMPEDIMENTS to technical progress, in one form or another. Each theory must be supplanted or overcome in some fashion for the next practical revolution in propulsion to come to fruition. None of these were dumb fellows, but they describe far more about human psychology and our limits of perception and follow-on analysis than about the firmament of all existence.

    Wrap your minds around this, fellow travelers: What if A VACUUM IS COMPLETELY FULL, and where there is matter there is a VOID? Just like the Vase and Faces illusion; which way can you chose to see it?

iamreddave · December 1, 2011 at 16:08

Back of the envelope Sputnik one was 7.7 km/s so we have doubled the speed in 50 years. Year 3000 we would have 20 doublings
or we would be at 3396156367km/s
Which would get us 4.3 light years in a day and a half 🙂

    admin · December 2, 2011 at 12:49

    Hi, thanks for your comments. I’ve no doubt spacecraft speeds can be increased but I doubt they’ll increase exponentially. (Historically this doesn’t happen, aircraft speeds levelled off on the 1960s.) Eventually too, relativity will get in the way. If intergalactic travel ever becomes feasible I’ll eat my shorts!

      iamreddave · December 2, 2011 at 15:13

      The reason planes did not get any faster is because they were good enough. You could already fly to Australia in a reasonable time in the 1960’s. We didnt need to get any faster.

      There are good arguments to why we wont travel to the stars. Many based on energies needed to speed up (and then slow down) a spaceship.
      We Won’t Have Enough Power For Interstellar Travel Until At Least 2211, According to New Calculations

      When will interstellar travel be possible?

      I just don’t find the “we are slow now” argument compelling. How long would a v1 take to go to the moon? That journey would not have seen possible.

        admin · December 2, 2011 at 21:41

        The reason planes did not get any faster is because they were good enough. You could already fly to Australia in a reasonable time in the 1960′s. We didnt need to get any faster.

        I’m not sure I agree with this, in the early ’60s, every one expected that SSTs and Mach 3 fightersand bombers would be common by 1980. Only by developing Concorde, the Tu-144 and the YF-12 did we discover high speeds weren’t worth the trouble. If some could build a Mach 3 airliner as cheap to run as a 747 we would. A flight to Australia is long!

        Please note again that I am not denying technologies yet to be developed will make interplanetary or even some interstellar travel attainable, just the the space opera idea of cruising the galaxy seems forever impossible.

      Michael · March 5, 2017 at 13:59

      Have you dismissed the possibility of static warp bubble based spacecraft, such as that designed by Alcubierre? Theoretically such technology would enable intergalactic travel; in fact any place within the visible universe would be accessible nearly instantly. The science is sound by our current understanding of physics but a working prototype is a long way off. However, NASA has been working on this and similar technologies and have had success. While a working prototype is still a long way off, it does present the realistic possibility of future intergalactic travel..

iamreddave · December 1, 2011 at 15:54

So new horizon is going at 16.1km/s and voyager in 1977 how has a speed of more then that
“Provided Voyager 1 does not collide with any stellar objects, the New Horizons space probe will never pass it, despite being launched from Earth at a faster speed than either Voyager spacecraft. New Horizons is traveling at about 15 km/s, 2 km/s slower than Voyager 1, and is still slowing down. When New Horizons reaches the same distance from the sun as Voyager 1 is now, its speed will be about 13 km/s (8 mi/s).[14] The close flyby of Saturn and Titan gave Voyager 1 a massive advantage with its extra gravity assist.”

But what was its initial speed before the gas giant gravity assist?
Say out orbital speed has increased 10% in 30 years. If it increased at the same rate in 3000 our spaceships would be going at 383km/s.

If spaceships speed increased at the same rate they have since Sputnik how long till the 4.3 lightyear trip to the next star takes under a hundred years?

Mankind’s next leap – Mars or the Moon? – Hypervelocity Science · July 10, 2016 at 16:39

[…] never, according to some people. The main issue would be the length of time required for us to reach even our closest galaxy, Alpha […]

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