# What would our world be like if e=m*c^3 [closed]

What would our world be like if e=mc3 ? What would happen to physics as a whole and what constants that we have now Change? How would they change?
How would stars exist and for how long? How much more energy would have to be added to the univers to have the same amount of mass we now have? How would chemistry work? What interactions we have foun would change? How would life exist at all?

• Welcome to the site, Midnightas. Please we aware that the Worldbuilding Exchange is not a "What-if?" site. Also, this question in its current form is definitely too broad and will likely be closed as such. If you could narrow the scope of your question to one specific aspect of a world, we would appreciate it. Commented Apr 10, 2016 at 17:38
• In general, you will find question in the form of "what if physics equation X became physics equation Y" do not fare well on stack exchange, because the answer is almost universally "the universe does not exist because it is inconsistent with itself." To explore questions like this, one really need to dig at which fundamental behavior of the universe you want to explore, rather than an equation related to it, and form the question around that. Even then, the answer is typically "The universe is so different from ours that you and I cannot even comprehend how different it is." Commented Apr 10, 2016 at 18:03
• That equation simply does not make sense. Energy has the dimensions of mass times velocity squared by definition. c might be faster or slower elsewhere but it has to be squared not cubed. Commented Apr 10, 2016 at 18:48
• Thing is that in natural units c = 1, the reason why c appears is due to us, for historical and practical reasons, wanting to use different units for different quantities while in principle you can make everything dimensionless. See here for how to get to E = m c^2 starting from natural units where E = M and never invoking any ad hoc unit system and using only scaling arguments. Commented Apr 10, 2016 at 20:15

## 1 Answer

This sort of question is difficult to answer without a deep knowledge of theoretical physics (which I don't have). You can't only change E = mc2, if you do physics will be inconsistent. Tremendous numbers of things change with it.

The problem is E = mc2 does not stand alone. It was derived from other formula and observations, and other formula are derived from it. If you change it, you have to make physics consistent with it again, and that would changing the laws of the universe so E = mc2 can be derived, and redoing things like General Relativity all over again.

That might make an interesting question on Physics.SE if phrased correctly: "what formulas does E = mc2 depend on, and what depends on it?" or "what physics would have to be reworked if E = mc2 changed to E = mc3?"

That aside, it is useful to answer the shallow version of the question: what if you could just change the E = mc2 to E = mc3? While impractical, it can serve to illustrate just how important the equation is.

E = mc2 is the mass-energy equivalence. Usually it's described as how much energy you get when you convert matter into energy, but that's not quite right. What it really says is matter is energy. Matter is just a special form of energy. This is why, for example, massless particles like photons (light) feel gravity. Gravity doesn't work on mass, gravity works on mass-energy.

A shallow consequence of E = mc3 is we'd have a lot less matter. A lot. 3x108 (300 million) times less matter. This is because E = mc3 can be expressed as m = E/c3. The amount of mass you get out of a certain amount of energy is now being divided by an extra factor of c or 3x108. Or looking at it the other way around, it now takes 3x108 times more energy to make matter. Since the amount of energy in the universe is constant, and it takes more energy to make matter, we'd have a lot less matter.

The flip side of this is what matter you do have now contains 300 million times more energy. This makes any sort of nuclear reaction, fusion and fission, far more energetic. This will throw stars out of whack in ways I'm not qualified to figure out.

• I don't normally vote up answers to questions that are obviously close-worthy as too broad such as this one, because we really shouldn't be encouraging people to ask questions that are not a good fit for the site, but this is a really great answer for showing just how massive (no pun intended) the impact of such a seemingly small change would be.
– user
Commented Apr 10, 2016 at 19:32
• I think you're missing the biggest problem with E=mc^3 - the units don't even make sense. Energy has units of mass * distance^2 / time^2 (this is necessitated, for example, by the fact that work is defined in terms of force * distance), whereas mc^3 has units of mass * distance^3 / time^3. Take your claim of getting more mass from a given amount of energy--whether E/c^2 has a larger numerical value than E/c^3 depends entirely on what units you choose to use for distance and time, so it can't be a meaningful physical truth that you'd get a larger equivalent m from a given value of E. Commented Apr 10, 2016 at 19:40
• 3e8 is specific to the units involved. If I choose units where c is 5, will I only have 1/5 as much mass? What about folks whomset c=1? Commented Apr 10, 2016 at 22:04
• @Hypnosifl Excellent point! Commented Apr 11, 2016 at 0:11
• @JDługosz I suppose it depends on how much mass you want ;). Commented Apr 11, 2016 at 1:38