A Touch Of Gravity: a non-floating article by GF Willmetts.
Let’s talk gravity. The real stuff, not the renamed variety used in Doctor Who’. At the base of every atom, there are four forces: electromagnetic, strong and weak forces and gravity, all having an effect on the particles/waves that make up the principle particles of protons and neutrons at the core, surrounded by ‘shells’ of electrons. Gravity is the odd one out, as it’s also extremely weak compared to the main three and, literally, very hard to define but probably is the main contributor to the core to keep the protons and neutrons mostly stable there. Yet, at our scale, it’s what keeps us on the Earth and takes a lot of force to leave the Earth to get into orbit.
An article about gravity in the third week of May’s ‘New Scientist’ caught my attention, particularly because it provided a metaphorical comparison to clarify my own thoughts. It remains to be seen whether they will print my letter on the subject, but since I have had two letters published there, I have decided to abandon my current plans and write an article on the topic where I can elaborate more.
For an atom, gravity is really an insignificant force. Like a grain of sand. If I dropped one on your head, you wouldn’t even feel it. If I opened a sack of sand over your head, apart from suffocating in the downpour, you would certainly know you’ve been hit by something as it falls to earth. Gravity becomes bigger as a collective than individually, especially as it falls in the same direction. A big bag of atoms probably wouldn’t do you much damage because atoms don’t float around individually. They tend to bond into molecules as elements and compounds when mixed and then become much larger. Sand then comes larger as its silicon oxide. Even though sand is a lot of individual small particles, when heated up, the particles merge and we get glass. Drop a panel of glass on your head and you would certainly feel it, if not fatally. Like sand, glass will still drop to the bigger, heaviest object, the earth below our feet. The speed of any falling object is the same unless it is caught in a wind that keeps it aloft. The size alone ensures that any falling object does not seek the same spot each time.
Everything falls to Earth and is easy to test and prove. In fact, both rise to meet each other; it’s just hard to see on our planet, which is too big. Matter is attracted to matter, which is what gravity is all about. Even the Moon is pulled towards the Earth, but the distance is great enough not to notice it happening, and other forces like centrifugal and centripetal forces have to be considered. In summary, the Moon is gradually moving towards the Earth at a rate of only a couple of millimetres per year, which is hardly significant.
Gravity remains a weak force when acting over long distances, but it becomes significantly stronger when concentrated in a smaller area. It varies with the different masses of planets. It also has to tolerate the different forces applied to it. When those are missing, you get a black hole or singularity, and we all know where that leads. Gravity still has its limits, and matter beyond its blue event horizon can’t be dragged in. Gravity might have a pull on any object, but distance reduces how much it can act.
When you consider how we can detect planets in distant star systems by very slight movements of the stars, then gravity has an effect on everything and is, literally, universal.
The odd thing about gravity is that for any large object, it is not what it contains but its size that controls the direction of gravity. Focus on that. If you had a heavy metal element embedded in the ground, a falling object wouldn’t move in its direction simply because it was heavy. It is the general mass of the biggest crucial object.
Going through the list of things gravity affects, it includes light. Considering light is essentially photons, then it has a minute mass and is moving fast in a particular direction, so it obviously can be affected by the gravity of any object nearby.
It’s also unlikely to ever be any anti-gravity. Although it’s been hypothesised that there is a graviton particle, there hasn’t been any evidence of one. If you could take it away, then the atom would fly away in free inertia, and we’ve never seen any evidence of that, not even in large masses. Any sizable object would quickly disassemble and fly off into space never to be collected again. If anti-gravity were possible, then we would surely have a high count of atoms or molecules in interstellar space. Before you ask about dark matter, even it has its gravity keeping it together.
Gravity will still bend to other forces. I already mentioned centrifugal and centripetal forces showing gravity is weak when faced with other motion forces. Any of these forces fade, and gravity asserts itself. Even the results of an explosion will still float to earth. Other forces impede but do not stop it.
The most obvious scientific laws that depend on gravity are Isaac Newton’s Laws of Motion, which is pretty obvious when they stretch out where an object can land, as with ballistics. The fact that it can be determined by maths gives gravity definable limits that can be measured.
Gravity is not a magnetic phenomenon, as that is something more associated with metals and can still cause metal to drop to the ground. It is an indication of mass staying together within limits.
Can gravity be exploited? Of course it can. All the time. We build structures like houses based on their application, knowing they will stay up with the right support. There are plenty of examples.
Can we exploit it for space travel? To some extent we can and already have. The size of the Apollo rockets to get the module beyond Earth orbit and keep going is a combination of that and using the Earth’s gravity against itself for propulsion in gravity assist. Yet the return trip requires a fraction of the fuel since Earth is the bigger object and drags the module back. The proposed trips to Mars will have different problems when returning, as, although the red planet has less mass, it is still too far away for Earth to drag the space vessel home, and any spacecraft will have to get a lot closer to take advantage of it.
Space vessels to the outer planets and beyond have used gravity assist to increase their acceleration rather than rely on fuel. They also have no intention of stopping.
Therein lies the problem with interstellar travel. The distance between planets, let alone stars, is too far to have the kind of gravitational attraction to draw any spacecraft along. To have a large enough mass always in front of a spacecraft would still need a means to propel it, and if that was possible, why bother to have it there in the first place?
Gravity is literally an odd force of nature, but it has self-determined limits as to what it can do. Nature likes to keep things tidy and together when it can. Without it, we wouldn’t amount to much. We are just a scattering of atoms. Mass is everything.
© GF Willmetts 2025
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