StarTalk Radio

The Limits of Knowing with Elise Crull

November 4, 2025

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  • Physics and philosophy were historically intertwined, with foundational figures like Newton writing works explicitly titled as 'Natural Philosophy,' demonstrating that early physics required philosophical grounding regarding epistemology and metaphysics. 
  • The increasing specialization of science, particularly in physics post-World War II, led to impermeable borders that discouraged cross-pollination with philosophy, which may be to the detriment of addressing fundamental conceptual issues at the edge of current physics. 
  • Quantum mechanics challenges traditional notions of objectivity because the act of measurement inherently involves interaction, making it impossible to isolate a quantum system from its environment without altering it, a problem that requires philosophical re-evaluation of basic concepts like space, time, and causality. 
  • Neil deGrasse Tyson expressed skepticism regarding the material contribution of 20th-century philosophy PhDs to the physical sciences, contrasting it with the historical role of philosophy in physics. 
  • The utility of formally trained philosophers to physics has diminished because physicists themselves are now absorbing philosophical thinking into their practice, though philosopher Elise Crull advocates for continued interdisciplinary dialogue. 
  • Einstein, in a letter to Schrödinger, noted the inseparable wedlock between physics and metaphysics, stating that physics describes reality only through its description, as we do not know what reality is independently. 

Segments

Defining Philosophy’s Role
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(00:04:55)
  • Key Takeaway: Philosophy today is defined by asking enduring questions within new scientific, cultural, and personal contexts, ensuring every inquiry is done anew.
  • Summary: Philosophy is not static; it evolves by re-examining old questions within contemporary frameworks. Philosopher Bas van Fraassen suggests that context—scientific, cultural, and personal—makes every philosophical inquiry unique. People who think deeply are those who change their minds most often, reflecting intellectual humility.
Physics and Philosophy History
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(00:06:53)
  • Key Takeaway: Early natural philosophers like Newton and Descartes explicitly integrated philosophical worldviews, such as epistemology, before deriving physical laws.
  • Summary: Aristotle viewed physics and metaphysics as intertwined, asking about the world’s patterns and behaviors. Descartes’ Principles of Philosophy established a philosophical worldview before detailing his physics, which Newton later countered with Mathematical Principles of Natural Philosophy. Newton’s Principia began with philosophical arguments for absolute space and time before presenting his laws of motion.
18th Century Physics Foundations
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(00:11:36)
  • Key Takeaway: Émilie Du Châtelet significantly advanced Newtonian physics by translating the Principia and writing a thick commentary that filled in conceptual gaps, particularly regarding the philosophical axioms underpinning the physics.
  • Summary: Du Châtelet wrote The Foundations of Physics starting with philosophical axioms like the principle of sufficient reason before deriving physical laws. She translated Newton’s Principia into French, adding commentary that clarified concepts Newton left underdeveloped. Her work was crucial for training subsequent physicists in the mid-1700s.
Calculus and Conceptual Debates
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(00:15:29)
  • Key Takeaway: Leibniz and Newton independently developed calculus, with Leibniz’s notation becoming standard in pure mathematics while Newton’s notation persists in physics.
  • Summary: Leibniz held a relational view of space, seeing it as relationships between matter, contrasting with Newton’s view of absolute space as an independent entity. Leibniz’s notation for calculus, including integral signs, is more elegant and is retained in modern mathematics. Physics often retains Newton’s notation, even when mathematical concepts are derived from Leibniz’s framework.
Post-War Physics Specialization
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(00:20:22)
  • Key Takeaway: The 19th century saw physics become quantitative and specialized, culminating in the post-WWII era where physics became a pragmatic, career-driven field focused on calculation, often sidelining philosophical inquiry.
  • Summary: The industrial revolution and growing scientific societies led to specialization, moving away from generalist philosopher-physicists. After WWII and the Manhattan Project, physics in the U.S. became highly pragmatic, adopting a “shut up and calculate” mentality due to national security interests. Figures like James Connaught at Harvard fought to keep history and philosophy of science mandatory for physics students to maintain broader perspective.
Quantum Mechanics and Objectivity
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(00:26:15)
  • Key Takeaway: The core challenge quantum mechanics poses to classical objectivity is that measurement of quantum systems requires interaction that cannot be cleanly separated or quotiented out, unlike classical observation.
  • Summary: The assumption of uniformity in nature is an untestable philosophical principle required to do science. Einstein believed a complete theory required a bijective mathematical state corresponding to a real system, which entanglement violates because subsystems cannot be described independently after interaction. Quantum decoherence explains why macroscopic objects appear classical, but the underlying non-separability remains a fundamental feature of quantum theory.
Future of Quantum Understanding
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(00:51:23)
  • Key Takeaway: Quantum physics is unlikely to become intuitive like classical physics because human evolution favored classical understanding, necessitating philosophical engagement to test assumptions and unmoor thinking from classical perspectives.
  • Summary: Human intuition is evolutionarily adapted to the macroscopic, classical world, making quantum concepts inherently difficult to grasp intuitively. Engaging with philosophical questions allows physicists to test underlying assumptions about concepts like causality and space when empirical testing is currently impossible. This philosophical work is necessary to maintain intellectual elasticity and explore new directions beyond ossified classical frameworks.
Location and Guest Gratitude
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(00:57:39)
  • Key Takeaway: Elise Crull is located near City College in Manhattan.
  • Summary: Elise Crull expresses enjoyment in conversing with the hosts. She notes that City College is located in Manhattan, a few miles north of their current location. The segment concludes with a final question directed to Neil deGrasse Tyson.
Philosophy’s Value to Physics
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(00:57:52)
  • Key Takeaway: Neil deGrasse Tyson claims no 20th-century philosophy PhD has materially advanced physical science understanding.
  • Summary: Neil deGrasse Tyson states his comments on philosophy have been caricatured, clarifying his stance. He asserts he has not seen a 20th-century philosophy PhD contribute materially to physical science understanding. The discussion seeks a single best example to counter this claim, leading to the mention of Abner Shimoni.
Dual PhD Example and Utility
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(00:59:01)
  • Key Takeaway: Abner Shimoni, possessing formal training in both physics and philosophy (two PhDs), exemplifies the intersection of the fields.
  • Summary: Abner Shimoni is identified as a philosopher formally trained in physics, holding PhDs in both disciplines. Neil deGrasse Tyson clarifies his point is about the utility of someone whose entire academic training is solely in philosophy compared to a century ago. He contrasts this with physicists who think philosophically without formal philosophy training.
Value of Philosophy in Science
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(01:00:16)
  • Key Takeaway: Philosophy of science is worth pursuing in its own right, separate from its direct contribution to empirical science.
  • Summary: It is argued that judging importance solely by contribution to science is a dangerous viewpoint. Philosophy of science is valuable intrinsically, and there is no hard line separating these disciplines, as evidenced by their historical unity. The utility of philosophers to physics has been absorbed by physicists engaging in philosophical thought themselves.
Academic Silos and Engagement
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(01:02:26)
  • Key Takeaway: A major problem is the lack of routine interaction between philosophy departments and science departments at academic institutions.
  • Summary: Elise Crull observes that philosophy departments rarely have lunch or interact with chemists or physicists at academic institutions she has observed. This lack of engagement leads to philosophical work disconnected from real science. Promoting dialogue is necessary for fruitful interdisciplinary learning.
Einstein on Physics and Reality
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(01:03:31)
  • Key Takeaway: Einstein believed physics is a form of metaphysics because it describes reality only through its description, which is inseparable from reality itself.
  • Summary: The conversation concludes by referencing an Einstein quote regarding quantum mechanics addressed to Schrödinger. Einstein stated that physics describes reality, but we only know reality through that physical description, making the two inseparable. This highlights the philosophical depth inherent in fundamental physics debates.