Why Reaching Another Galaxy Is Not Impossible

Our nearest galaxy, Andromeda, is 2.5 million light years away. With today's technology, using the fastest probes ever built, the journey there would take billions of years. Most videos I've seen on this topic stop right there, concluding that it is impossible. But is that really the final answer? Or is it simply what seems obvious to us because we think in terms of timescales suited to a human lifespan? Here is why most people say it is impossible. First, the distance itself, 2.5 million light years. Second, energy. To even approach a significant speed, you would need amounts of energy far beyond the capabilities of current technology. Third, fuel. Every kilogram you accelerate has to be carried along, and the fuel itself has weight. Fourth, radiation. Intergalactic space is not an empty void. Cosmic radiation would almost certainly kill a crew over such long periods. And fifth, a human life is simply too short. Even a hundred years is a mere blink of an eye compared to millions of light years. Given the current state of technology, a journey to another galaxy is practically impossible. That is, however, based on our current understanding, and there is a difference between practically impossible and physically impossible. Let's talk about time itself first. When we hear 2.5 million light years, we automatically convert that into Earth time. But Earth time isn't the only time that matters. Einstein showed that time doesn't pass at the same rate for everyone. It depends on how fast you are moving. The closer you get to the speed of light, the slower your clock runs, from the perspective of a stationary observer. Imagine sitting in a spaceship traveling at a speed extremely close to that of light, outside millions of years pass on Earth. For you on board, something completely different happens. Your clock ticks more slowly. Time itself behaves differently for you. This isn't just an interpretation or one theory among many. Time dilation has been measured in atmospheric muons and in atomic clocks on airplanes. It is real, and this is where the journey begins to become theoretically achievable. Two effects come into play here. Time dilation, as just described, and length contraction. For a traveler moving at near light speed, the distance ahead appears shorter. This isn't because space itself folds up, but because distance, just like time, is relative to the observer. From the traveler's perspective, the distance shrinks, a consequence of the same relativity that distorts time. Crucially, this isn't a trick to travel faster than light. The speed of light remains the ultimate limit. What changes is the subjective experience of space and time for someone approaching that limit. So, could a human actually reach Andromeda within a single lifetime? The most important factor is, logically, speed, or more precisely, how close one gets to the speed of light. At 90% of light speed, you still wouldn't make it to Andromeda in a single lifetime. Not even at 99%. The effect only becomes significant at speeds that are absurdly close to the speed of light. We're talking about something on the order of 99% with nine nines. With every additional nine after the decimal point, the time dilation changes drastically. At such a speed, a single human lifetime might be enough for the travelers on board to reach Andromeda. Yet, back on Earth, millions of years would still pass. Nothing changes that fact. It is not an exception, but precisely what the theory of relativity predicts. And no, space does not fold up in the process. There is no shortcut through the cosmos. The only thing that changes is the travelers' proper time. From Earth's perspective, their clock ticks extremely slowly. From their own perspective, it ticks quite normally. It's just that far less time is required. The problem is that reaching such a speed is currently miles beyond the capabilities of any known propulsion technology. So, the theory of relativity does not strictly rule out such a journey. But what she states very clearly is this. Without a speed so close to the speed of light, the entire idea remains all but impossible. So, distance isn't necessarily the main problem. Energy is. To accelerate a probe, just a probe, no humans, to a significant fraction of the speed of light requires amounts of energy that exceed current global energy consumption by orders of magnitude. For a crude ship with life support, shielding, and supplies for generations, that figure becomes even more absurd. Fusion propulsion would be a step in the right direction. But even that is hardly sufficient for relativistic speeds. Antimatter offers the best chance of approaching what is needed. Matter-antimatter reactions release practically the entire rest mass as energy. The problem is that, so far, we can only produce minuscule amounts of antimatter, and at an exorbitant cost. As I said, physics doesn't rule it out as impossible. But it is extremely difficult. But when you consider what we are talking about here, traveling to other galaxies that are an absurd distance away, it makes sense that it would be difficult. To contextualize warp drives and wormholes, since the topic inevitably comes up, where do they stand scientifically? Time dilation has been experimentally confirmed. Relativistic space travel using conventional propulsion is theoretically possible. It is purely a matter of technology. Warp drives are mathematically conceivable within the framework of general relativity. However, every known solution requires exotic matter with negative energy density. Nothing of the sort has been observed to date. It may not even exist in a usable form. Wormholes are purely hypothetical. They are mathematically permissible. Yet, there is no indication that they actually exist or could be kept stable. Interesting concepts. Not a realistic solution. At least, not based on what we know today. Here is a thought that is often overlooked. Who says a biological human needs to be on board at all? AI-controlled probes require no life support, food or radiation protection on the scale a human would need. They could withstand tremendous acceleration that would crush a human being. Self-replicating machines could multiply and spread, either en route or upon arrival, without the constant need for new resources from Earth. Generation ships represent another concept. Instead of extreme speed, they involve humans who are born, live and die on board, spanning generations, until a generation eventually arrives that has never seen the home planet. Some even speculate about digital forms of consciousness that would experience the journey in a completely different way than a biological body. Perhaps it will not be biological humans who reach the next galaxy first. Today, practically impossible. With our technology, our energy production and our materials, not a chance. According to known physics, not strictly forbidden. Time dilation works. The mathematics allows for such travel, provided there is enough energy and time available. For a highly advanced civilization, something like this could become possible. That is the difference between technical impossibility and physical impossibility. Technical impossibility means we simply can't do it right now. Physical impossibility means it cannot work in principle. A little over a hundred years ago, the mere idea of flying seemed absurd to most people. Before the moon landing, a flight to the moon was considered pure fantasy, even by many engineers of that era. My point is, as long as something isn't ruled out by known physics, we should be cautious about labelling it fundamentally impossible. Our understanding of physics is constantly evolving. Laws we currently regard as immutable could be expanded upon by more comprehensive theories in the future, just as Einstein's theory of relativity expanded upon Newtonian physics. Science as we know it today hasn't existed for very long relative to our entire existence. We are still in the very early stages, yet our progress is incredibly rapid, especially in recent years. Just imagine what things might look like in 100 or 1000 years, given the rate of progress we're seeing now. I hope you enjoyed the video and I'll see you next time.