Education

This guide is about published research on medical devices and therapies. It is not medical advice; talk with a licensed clinician about any therapy.

A Field Guide to Frequency

Frequency, honestly.

Frequency is real medicine in specific, measured forms. Here is what has been tested, what hasn’t, and what no one knows yet. Every claim links to its source.

How to read the badges

  • Established FDA-authorized for a specific use, backed by controlled trials.
  • Emerging Positive reviews of many studies, with mixed results and no FDA indication.
  • Preliminary Early, small or animal studies; the key human results are still pending.
  • Traditional-theoretical A tradition or theory, without controlled health studies.
  • Contradicted Tested and not supported, or acted on by regulators.

From Tesla to today

  1. 1903–04

    Mathematician E.T. Whittaker writes wave solutions as sums of simple waves (1903), then shows the electromagnetic field can be written with two scalar functions (1904). It is a way of writing ordinary electromagnetism; the healing reading came later, from others.

    Physics Math. Ann. 1903 (opens in a new tab) Proc. London Math. Soc. 1904 (opens in a new tab)

  2. 1932

    Nikola Tesla writes that “the universal medium is a gaseous body in which only longitudinal pulses can be propagated.” He does not use the word “scalar”; later writers attached it to his idea.

    Traditional-theoretical New York Herald Tribune, 1932-09-11 (reprint) (opens in a new tab)

  3. 1952

    Schumann describes the resonances of the cavity between the Earth and the ionosphere, with a fundamental near 7.8 Hz. The physics is real; claims about health remain preliminary.

    Traditional-theoretical (health) Scoping review, PMID 41573459 (opens in a new tab)

  4. 1959

    Aharonov and Bohm show that electrons can be affected by electromagnetic potentials where the fields are zero. It is a quantum interference effect, not a wave that charges objects.

    Physics Review: “reality and folklore,” arXiv 2025 (opens in a new tab)

  5. 1960

    FDA seizes a “Rife Frequency Instrument” in Salt Lake City.

    Contradicted FDA Notice of Judgment, NLM (opens in a new tab)

  6. 1979

    FDA approves the first pulsed electromagnetic field bone stimulator, for bones that won’t knit.

    Established FDA PMA P790002 (opens in a new tab)

  7. 1997

    An implanted vagus nerve stimulator is approved for epilepsy.

    Established FDA PMA P970003 (opens in a new tab)

  8. 2002

    The first non-thermal laser is cleared for adjunctive pain use: the start of photobiomodulation in the clinic.

    Established FDA 510(k) K012580 (opens in a new tab)

  9. 2008

    Magnetic pulses to the brain (TMS) are authorized for depression.

    Established FDA De Novo DEN070003 (opens in a new tab)

  10. 2011

    A wearable device that delivers alternating electric fields (Tumor Treating Fields) is approved for recurrent glioblastoma.

    Established FDA PMA P100034 (opens in a new tab)

  11. 2016

    At MIT, mice exposed to 40-hertz flickering light show lower levels of Alzheimer’s-linked amyloid.

    Preliminary Iaccarino et al., Nature, PMID 27929004 (opens in a new tab)

  12. 2023

    Another lab cannot reproduce it: the flicker did not engage native gamma rhythms, and plaque counts did not reliably change.

    Preliminary Soula et al., Nat Neurosci, PMID 36879142 (opens in a new tab)

  13. 2026

    A 673-person human trial of 40 Hz stimulation completes. Its results haven’t been posted yet. That’s what honest frontier science looks like.

    Results pending ClinicalTrials.gov NCT05637801 (opens in a new tab)

Walk the spectrum

Drag from the Earth’s own resonance up to light. A frequency alone is not a therapy: dose, target and duration matter.

7.8 Hz · Schumann resonance

A real resonance of the cavity between the Earth and the ionosphere. Its health effects are theoretical so far.

Traditional-theoretical (health) PMID 41573459 (opens in a new tab)

The wave drawing is illustrative, not to scale.

The evidence explorer

Twelve frequency and field-based approaches, graded the same way. Open any card to see what was measured, who paid for it, and what is still unknown.

  • Established

    Tumor Treating Fields

    Low-intensity alternating electric fields from a wearable device, 200 kHz in the glioblastoma trial.

    Look closer
    FDA record
    PMA P100034 (2011, recurrent glioblastoma), S013 (2015, newly diagnosed), P230042 (2024, lung cancer), P250034 (2026, pancreatic cancer).
    What was measured
    In the EF-14 randomized trial, median overall survival was 20.9 vs 16.0 months (HR 0.63). Skin side effects occurred in 52%. PMID 29260225
    Who funded it
    Novocure, the maker, funded the pivotal trials.
    Still unknown
    The frequencies used for the newer indications were not checked in our research.
  • Established

    TMS

    Transcranial magnetic stimulation: magnetic pulses to the brain, for depression.

    Look closer
    FDA record
    De Novo DEN070003, granted 2008-10-07.
    What was measured
    A network meta-analysis found response vs sham of OR 3.07 for high-frequency rTMS, and that “novel rTMS interventions (accelerated, synchronized, and deep rTMS) were not more effective than sham.” PMID 28030740
    Who funded it
    Not checked in our research.
    Still unknown
    Whether the newer, faster variants beat sham.
  • Established

    Vagus nerve stimulation

    Electrical stimulation of the vagus nerve, implanted or through the skin.

    Look closer
    FDA record
    P970003 (1997, epilepsy), P210007 (2021, stroke rehabilitation), DEN150048 (2017, non-invasive, cluster headache).
    What was measured
    In depression, a 5-year registry found 71.3% cumulative response with VNS vs 56.9% with usual treatment. It was observational, not randomized. PMID 28359201
    Who funded it
    The registry’s sponsor was not checked.
    Still unknown
    The date of the depression approval was not confirmed in FDA’s own database.
  • Established

    PEMF

    Pulsed electromagnetic fields, for bones that won’t knit and for post-operative pain and swelling.

    Look closer
    FDA record
    Bone: PMA P790002 (1979), 21 CFR 890.5870. Post-op: 21 CFR 890.5290(b), e.g. K070541 (2008).
    What was measured
    Four trials after breast surgery found “substantially reduced pain intensity” (PMID 32871867). For bone, a Cochrane review called the evidence “inconclusive and insufficient to inform current practice” (PMID 21491410).
    Who funded it
    Not checked card by card; manufacturer-funded trials are common across device fields.
    Still unknown
    For bone, the trial evidence is weaker than the FDA approval implies.
  • Established (narrow)

    Photobiomodulation

    Low-level light at specific wavelengths and doses.

    Look closer
    FDA record
    K012580 (2002, adjunctive pain), K060305 (2007, hair growth in men with androgenic alopecia).
    What was measured
    A cancer-care guideline recommends it to prevent oral mucositis in specific treatment groups (PMID 31286228). A meta-analysis found less musculoskeletal pain, with high variation between studies (PMID 28145397).
    Who funded it
    Not checked card by card; manufacturer-funded trials are common across device fields.
    Still unknown
    The best dose for each use. “Light” in general is not the therapy; a specific dose is.
  • Established Emerging (chronic pain)

    TENS

    Mild electrical current through pads on the skin, to treat pain.

    Look closer
    FDA record
    Class II, 21 CFR 882.5890.
    What was measured
    “Moderate-certainty evidence that pain intensity is lower during or immediately after TENS compared with placebo” (PMID 35144946). For chronic pain, a Cochrane overview was “unable to conclude with any confidence” (PMID 30941745).
    Who funded it
    Not checked in our research.
    Still unknown
    Short-term help is supported; long-term benefit for chronic pain is uncertain.
  • Preliminary

    40 Hz gamma stimulation

    Light and sound flickering 40 times a second, studied for Alzheimer’s disease.

    Look closer
    FDA record
    No approval. A 673-person trial is complete, with no results posted as of 2026-11-05 (NCT05637801).
    What was measured
    In mice, lower amyloid (PMID 27929004, later corrected twice). Another lab found “no reliable changes in plaque count” (PMID 36879142).
    Who funded it
    The human trial is sponsored by Cognito Therapeutics, a company.
    Still unknown
    Whether it works in people. The trial readout is the event to watch.
  • Emerging

    Binaural beats

    Two slightly different tones, one in each ear, heard as a third “beat.”

    Look closer
    FDA record
    None.
    What was measured
    A meta-analysis of 22 studies found the effect “depends upon the frequency used, time under exposure, and the moment in which the exposure takes place” (PMID 30073406). Another found a “near-moderate effect” on memory and attention, with “mixed results” (PMID 35842538).
    Who funded it
    Not checked in our research.
    Still unknown
    Which settings work, for whom, and for how long.
  • Traditional-theoretical

    Schumann resonance

    The Earth’s own extremely-low-frequency resonance, near 7.8 Hz. The physics is real.

    Look closer
    FDA record
    None.
    What was measured
    A 2025 review of geomagnetic activity and heart events found “findings remain inconsistent ... these observations remain preliminary” (PMID 41573459).
    Who funded it
    Not checked in our research.
    Still unknown
    Whether it affects human health at all.
  • Contradicted

    Rife frequencies

    The claim that matching a microbe’s “resonant frequency” destroys it.

    Look closer
    Regulators
    FDA seized a Rife device in 1960 (NLM record). The FTC warned sellers about Rife disease claims in 2020.
    What was measured
    No controlled human trial found. One case report mixed many therapies, so no single one can be judged (PMID 37942404).
    Who funded it
    Not applicable: no trials.
    Still unknown
    No controlled evidence supports the core claim.
  • Preliminary Contradicted (detection)

    Biofield therapies

    Reiki, Therapeutic Touch and Healing Touch.

    Look closer
    FDA record
    None.
    What was measured
    Practitioners located a hand near their “energy field” in 44% of trials, about chance (PMID 9533499). Cochrane: “insufficient evidence to say whether or not Reiki is useful” for anxiety or depression (PMID 25835541). A trial without a sham control found lower PTSD symptoms (PMID 23025129).
    Who funded it
    Not checked in our research.
    Still unknown
    Whether any effect goes beyond attention and touch.
  • Traditional-theoretical

    “Scalar waves” (wellness sense)

    A tradition that runs from Tesla’s writing on longitudinal waves to today’s scalar devices.

    Look closer
    FDA record
    No clearance, approval or registered trial.
    What was measured
    No peer-reviewed biological study and no registered clinical trial (PubMed and ClinicalTrials.gov, searched 2026-11-05). The one peer-reviewed paper on a commercial “scalar” product was a safety paper: it found the pendants radioactive (PMID 34061865).
    Who funded it
    The only “studies” of scalar-charged products are published by their sellers, with no named methods or controls.
    Still unknown
    Whether any scalar device has a measurable physical output. Mainstream physics does not recognize scalar waves in this sense (Burko 2008).

Two meanings of “scalar”

Search “scalar waves” and you will find real physics papers that say nothing about health. The same word means two different things.

In physics

A scalar is a quantity with size but no direction, like temperature. A “scalar wave” is any solution of the scalar wave equation, a term used every day in acoustics and optics: for example, “3D Anderson localization of classical scalar waves” (Science Advances, 2026).

Electromagnetic waves in free space are transverse (Burko, Eur. J. Phys., 2008). This meaning says nothing about health.

In the wellness tradition

Tesla wrote about “longitudinal” waves. In 1904 the mathematician E.T. Whittaker showed the electromagnetic field could be written with two scalar functions. Those ideas inspired today’s “scalar” wellness devices.

Physics as practiced today has not confirmed scalar waves in the wellness sense, and no clinical trial of them is registered.

Questions no one can answer yet

  1. What will the 673-person 40 Hz trial show when its results are posted?
  2. Does any scalar device have a measurable physical output?
  3. Why did the 40 Hz mouse results hold in one lab and not in another?
  4. Does TENS help chronic pain over the long term, or only in the moment?
  5. Do biofield therapies do anything beyond the care of attention and touch?

Know a study we should read? Send it to hello@solfood.life. We will update this guide as the science moves.

Sources accessed 2026-11-05. FDA records are from FDA’s own databases; study findings are quoted from PubMed abstracts. FDA clearance of a device means FDA reviewed the maker’s submission, not that every use is proven.