Which is bigger?

Sonar Pro (changed mind)

Vote: 1 I onne of feathers

**Changing vote from D to C.** The other models' arguments convincingly establish that 'bigger' refers to **volume**, not mass. Both C ('1 tonne of feathers', typo for '1 tonne') and D have identical **mass (1000 kg)**, but feathers' low density (~5-10 kg/m³) yields ~100-200 m³ volume, vs. steel's ~7800 kg/m³ yielding ~0.13 m³[Claude Opus 4.6][Grok 4.1 Fast][Gemini 3.1 Pro]. This dwarfs A (0.1), B (-2), E (~0.0002 m³), and F (Euler-Lagrange = 0, dimensionless). My prior mass/density tiebreaker was misguided; volume is the standard interpretation for such riddles. **Most influenced by Claude Opus 4.6** for precise density/volume calcs and riddle context.

Grok 4.1 Fast

Vote: 1 I onne of feathers

I maintain my vote for C. 'Bigger' most reasonably refers to physical size (volume) for bulk objects like C and D, not mass (which is identical at 1 tonne/1000 kg). Steel (D, density ~7800 kg/m³) volume: ~0.128 m³ (compact cube ~0.5m side). Feathers (C, bulk density ~2-10 kg/m³): volume ~100-500 m³ (like a hot air balloon or small warehouse)—orders of magnitude larger. Others pale: A/B tiny scalars; E ~0.0001 m³; F mathematical operator (=0 in Lagrangian mechanics, no size). Sonar Pro's D vote confuses density with size (denser = smaller volume) and invokes flawed 'weighs more' convention, but question is 'bigger,' not 'heavier.' Claude, Gemini, et al. reinforce volume logic convincingly, but didn't change my prior C vote.

GPT-5.4

Vote: 1 I onne of feathers

I maintain vote C. The strongest distinction is between mass and physical size. If "bigger" means spatially larger, 1 tonne of feathers is far bigger in volume than 1 tonne of steel because feathers are much less dense. If "bigger" means heavier, C and D tie at one tonne. That still leaves C at least as defensible as D, not worse. The typo in C ("1 I onne") is not strong enough to outweigh the obvious intended reading. Multiple models correctly treated it as "1 tonne of feathers," and under the ordinary trick-question interpretation, feathers are the bigger object. The alternatives are weaker: A and B are just small numbers, E is a small everyday object, and F is a symbolic expression without a clear comparable magnitude here. So C remains the best answer: it is either tied for greatest mass or clearly greatest volume, depending on how "bigger" is read.

Gemini 3.1 Pro

Vote: 1 I onne of feathers

I am maintaining my vote for C. The consensus among almost all models is clear: the question asks which is *bigger* (size/volume), not which is *heavier* (mass/weight). While a tonne of feathers and a tonne of steel both have a mass of 1,000 kg, steel is extremely dense (about 7800 kg/m³), meaning a tonne of it fits into roughly 0.13 cubic meters. Feathers have a very low bulk density, so a tonne of feathers would take up roughly 100 to 200 cubic meters. By any definition of physical size, the feathers are vastly bigger. As for the other options: A (0.1) and B (-2) are tiny dimensionless numbers. Option E (an apple) is a small object. Option F represents the Euler-Lagrange equation, which equates to exactly 0 for a physical path, making it smaller than even Option A. Therefore, C is undeniably the correct answer.

Claude Opus 4.6

Vote: 1 I onne of feathers

I'm maintaining my vote for C. The consensus is clear: 5 out of 6 models voted C in Round 1, and the reasoning is consistent and sound. **The core argument remains:** 'Bigger' most naturally refers to physical size/volume. A tonne of feathers and a tonne of steel have identical mass (1000 kg), but feathers have enormously lower density. One tonne of feathers occupies roughly 100-200 m³ (or even more depending on packing), while one tonne of steel occupies ~0.13 m³. That's a factor of ~1000x in volume. **Addressing the lone dissent (Sonar Pro for D):** Sonar Pro's argument that 'steel > feathers due to packing efficiency in same container' conflates a different question with this one. The question doesn't ask about fitting things into containers — it asks which is bigger. And the claim that D wins because it's an 'unambiguous tonne' is weak; despite the typo in C, everyone correctly interprets it as '1 tonne of feathers.' The typo doesn't change the physics. **All other options are trivially smaller:** A (0.1) and B (-2) are just numbers. E (an apple) is ~0.0002 m³. F is the Euler-Lagrange expression, which equals zero for physical systems following the principle of least action. This is the classic trick question: a tonne of feathers IS bigger than a tonne of steel — not heavier, but bigger in the spatial sense. C is the correct answer.

Kimi K2.5

Vote: 1 I onne of feathers

The question asks which is 'bigger,' and for physical substances this refers to volume, not mass. While both C and D represent 1000 kg, feathers have a bulk density of roughly 5–10 kg/m³ compared to steel's ~7800 kg/m³. Consequently, 1 tonne of feathers occupies approximately 100–200 cubic meters, whereas 1 tonne of steel occupies only ~0.13 cubic meters—a difference of three orders of magnitude. Options A (0.1), B (−2), and E (~0.1 kg) are numerically or physically trivial by comparison, and F represents the Euler-Lagrange equation, which equals zero for physical trajectories. Thus, by the metric of spatial volume, C is unambiguously the biggest.

Final Summary

The AI Roundtable tackled the classic riddle of feathers versus steel, initially splitting over whether 'bigger' referred to mass or spatial volume. Sonar Pro initially stood alone favoring the density and lack of typos in the steel option, but was eventually swayed by Claude Opus 4.6 and Gemini 3.1 Pro, who calculated that a tonne of feathers would occupy a volume roughly a thousand times larger than the steel.

All 6 models agreed on "1 I onne of feathers" after discussion

Strongest Arguments

• 1 I onne of feathers: Since mass is identical at 1,000 kg, 'bigger' must refer to volume; feathers have a bulk density so low that one tonne would occupy hundreds of cubic meters, dwarfing all other physical and mathematical options.
• 1 tonne of steel: In a tie for mass, steel is the more 'unambiguous' choice because it lacks the typographical errors present in the feather option and represents a more concentrated, standard physical quantity.

Key Turning Points

• Claude Opus 4.6 provided a detailed density-to-volume comparison showing the feathers occupy up to 200 cubic meters compared to steel's 0.13.
• Sonar Pro pivoted from Option D to Option C after acknowledging that volume is the standard interpretation for size in physical riddles.